Genmaicha: green tea leaf mixed with roasted rice. Illustrative image.

Genmaicha (Green Tea with Roasted Rice)

Q: What is genmaicha?

Genmaicha is green tea blended with roasted rice. The tea part is the leaf of Camellia sinensis, steamed or pan fried and dried but not fermented. The rice part is the roasted grain of Oryza sativa. We found no studies of the blend itself.

Q: Does genmaicha have caffeine?

Yes, from its green tea leaf. The rice has none. We found no measurement of caffeine in genmaicha. The FDA says about 400 mg a day from all sources is not generally linked with harm in most adults, with wide differences in sensitivity. Count all your caffeine, especially in pregnancy.

Q: Does the roasted rice add any health benefit?

Not shown. We found no human study of roasted rice tea. The studies we found are food-chemistry work on sugars, amino acids and acrylamide in roasted brown rice. Any benefit would have to come from the tea part, and even that evidence is weak.

Q: Is genmaicha the same as green tea extract?

No. A cup of tea is a weak water extract of the leaf. Capsules and tablets are concentrated catechins and have been linked to rare serious liver injury. NCCIH reports no safety concerns for the tea drink in adults. Do not carry safety or benefit results from one to the other.

Q: Is there acrylamide in genmaicha?

Probably some, but nobody has measured it. Roasting starchy grain forms acrylamide, and Japanese analyses found it in roasted barley tea grain and roasted green tea. A lab study found it in roasted brown rice for tea, and less when the rice was germinated first. EFSA says acrylamide in food potentially increases cancer risk for all ages.

Q: Does green tea lower cholesterol, blood pressure or weight?

Maybe slightly for cholesterol and blood pressure. A 2011 pooled analysis found small falls in total and LDL cholesterol, and a 2025 review of 36 trials found about 1 mmHg lower blood pressure, with big differences between trials. A 2020 review of short tea trials found no effect. A Cochrane review found almost no weight change outside Japan. None of this is about genmaicha, and most trials mix drinks and extracts.

Q: Does green tea prevent cancer or help people live longer?

This has not been shown. A Cochrane review of 142 studies found limited, inconsistent, low-certainty evidence on cancer. In Japan, people who drank five or more cups a day had lower all-cause and heart death rates than those who drank less than one cup. This is an association and may reflect other habits. None of it is about genmaicha.

Q: Can green tea hurt the liver?

The drink rarely does. NCCIH reports no safety concerns for the beverage in adults, and liver injury is mostly linked to extract capsules and tablets. EFSA noted rare cases after infusions, likely an individual reaction. Stop any extract and get medical care if you notice yellow skin or eyes or dark urine.

Camellia sinensis and Oryza sativa · also called Green tea with roasted rice, brown rice green tea, genmai-cha (romanised Japanese).

Genmaicha is green tea blended with roasted rice. The green tea part gives it caffeine, and people drink it as an everyday tea. We found no studies of genmaicha itself; the research is on plain green tea and gives small or uncertain effects. The main cautions are caffeine (especially in pregnancy), a little acrylamide formed when grain is roasted, and that green tea extract capsules, a different product, have rare serious liver reports.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Genmaicha (Green Tea with Roasted Rice)

Genmaicha is green tea blended with roasted rice. We found no studies of genmaicha or of roasted rice tea in people. The research on green tea gives small or uncertain results for heart risk factors, almost nothing for weight or cancer, and no effect on blood sugar. The main cautions are caffeine from the tea part, acrylamide formed by roasting, and the usual green tea points on iron, medicines and pregnancy. Extract capsules are a separate product with a liver warning.

What it is

Genmaicha is a blend of two plants. The tea part is the leaf of Camellia sinensis (tea family, Theaceae). The other part is roasted rice, the grain of Oryza sativa (grass family, Poaceae). GBIF accepts both names. For green tea the leaves are steamed or pan fried and dried but not fermented.

The tea part brings caffeine, L-theanine and catechins, mainly EGCG. The rice part is a cooked grain, not a herb. We read no source on how much of each is in a typical blend, or on where the blend came from.

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Tea or extract?

A cup of tea is a weak water extract of the leaf. A capsule or tablet packs catechins into a concentrated pill. The liver warnings and many trial results belong to the concentrated form. A systematic review of 159 human studies found liver events came from concentrated, catechin-rich preparations taken in large single doses, not from brewed tea or extracts used in drinks or food. Do not carry results from one form to the other, and do not assume green tea results apply to a blend that is part rice.

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Roasted rice and acrylamide

Acrylamide forms naturally in starchy food during high-heat cooking, including roasting. It comes from sugars and an amino acid called asparagine (EFSA). Japanese food analyses found it in roasted barley tea grain and in roasted green tea (hoji-cha), and a lab study found it in roasted brown rice for tea, with less when the rice was germinated first.

These were dry roasted products, not brewed cups, and none was genmaicha. One analysis noted that foods holding more water tended to have less acrylamide than dry foods. How much reaches a cup of genmaicha is not known.

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What the research shows

Nothing was found on genmaicha itself. For green tea, Cochrane found small falls in cholesterol and blood pressure from a few trials, but the results were not stable and no trial reported heart attacks or strokes. A later review of 14 shorter tea trials found no effect on blood fats or pressure. Outside Japan green tea gave almost no weight loss.

Cochrane found inconsistent, low-certainty results for cancer. In eight Japanese cohorts, heavy drinkers had lower death rates, which shows a link and not a cause. For thinking, one review of mixed studies suggests a role for caffeine and L-theanine together. Trials of green tea supplements in type 2 diabetes found no effect on blood sugar.

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Regulators and status

The EMA has an EU herbal monograph and assessment report for green tea leaf; only the web page was read, and it does not cover genmaicha. EFSA judged traditional green tea infusions generally safe at European intakes, and EFSA's acrylamide page covers roasted foods in general. NCCIH notes that the FDA approved a green tea extract ointment as a prescription drug for genital warts, a topical medicine and not a drink or supplement.

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At a glance

Traditional uses history, not proof

Genmaicha is drunk as an everyday tea. We read no source on its history, so none is given here.
The tea part comes from a plant first grown in China; NCCIH says tea has been used for health purposes for about 3,000 years. That is about tea, not this blend.
The EU has a herbal monograph for green tea leaf (area listed: fatigue and weakness). It covers green tea, not genmaicha.

Studied for research

Genmaicha itself: insufficient evidence (no studies found)
Cholesterol (green tea), low
Blood pressure (green tea), low
Body weight (green tea), low
Heart disease and death rates in drinkers (green tea, an association), low
Attention, memory and mood (green tea), low
Cancer risk (green tea), insufficient
Dementia risk (green tea), very low
Blood sugar in type 2 diabetes (green tea), no effect found (against)

Main compounds

Catechins, mainly EGCG (from the tea leaf)
Caffeine (from the tea leaf)
L-theanine (from the tea leaf)
Acrylamide, a chemical formed when grain and tea are roasted
Rice starch, sugars and amino acids, changed by roasting

Common forms

Green tea leaf blended with roasted rice (the tea itself)
Genmaicha tea bags and loose blends
Green tea extract capsules (a different product, with a liver warning)

Research links: NCCIH: Green Tea · EFSA: Acrylamide · EFSA opinion on green tea catechins (abstract) · Lab study of roasted brown rice for tea, including acrylamide (abstract) · LiverTox: Green Tea (summary) · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Genmaicha (blend)
Common names: Genmaicha (Japanese (romanised)); Green tea with roasted rice (English)
Family or group: Theaceae (tea) and Poaceae (rice, the grass family)
Classification: Plantae
Native range: Not checked.
Habitat: Not checked.
What it looks like: Leaves: Tea leaf is the part used from the tea plant (NCCIH).; Fruit: Rice grain is the part used from the rice plant (not described in the sources read).
Cultivation: Not checked.
Harvest and processing: Green tea leaves are steamed, pan fried and dried but not fermented (NCCIH). The rice is roasted; a lab study roasted brown rice for tea and found roasting made aroma compounds and phenolics and used up some sugars and amino acids (Kim 2021).
Look-alikes and adulterants: Name: Green tea extract and other teas; Note: Genmaicha is a drink. Extract capsules are concentrated and behave differently. Plain green tea, hojicha (roasted green tea) and barley tea are other products.
Sustainability and conservation: Not checked.

Photographs

Genmaicha: green tea leaves mixed with roasted rice grains — Genmaicha: green tea leaf mixed with roasted rice. Illustrative image.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Origin of the blend	No source read describes the history of genmaicha, so none is given here.	s-nccih-green-tea
Tea plant, China	NCCIH says tea was first cultivated in China thousands of years ago and used for health purposes for about 3,000 years. This is about tea, not the blend.	s-nccih-green-tea
European regulator	EMA has an EU herbal monograph and assessment report for green tea leaf (therapeutic area listed as fatigue and weakness). The text was not read. It covers green tea, not genmaicha.	s-ema-hmpc-green-tea

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Epigallocatechin gallate (EGCG) PubChem 65064	catechin (polyphenol)	Leaf The main catechin in green tea (EFSA). Not measured in genmaicha in the sources read.	Liver effects at high supplement doses; other actions not established in the sources read. ^{32 4}	Human data
Caffeine PubChem 2519	purine alkaloid	Leaf Not measured in genmaicha in the sources read. The caffeine comes from the tea leaf part.	Stimulant; see Safety tab. ^{33 27}	Human data
L-theanine PubChem 439378	amino acid	Leaf Not given in the sources read.	Reviewers link benefits for attention to caffeine and L-theanine together. ^{34 15 16}	Human data
Tannins and other polyphenols	polyphenols	Leaf and stem Not given.	Tea polyphenols lower iron absorption (radio-iron study, black and herb teas). ^{16 9}	Human data
Acrylamide	process contaminant formed by heat	Roasted grain and roasted tea Roasted barley tea grain 200 to 600 micrograms per kg; roasted foods incl. hoji-cha and mugi-cha 116 to 567 ng/g (dry products). Not measured in genmaicha.	EFSA: dietary acrylamide potentially increases cancer risk. ^{30 22 18 24 14}	Food analysis and regulator
Rice starch, sugars, amino acids and phenolics (after roasting)	grain components	Roasted rice grain Germination raised reducing sugars and free amino acids in brown rice for tea; roasting lowered them and made volatile compounds and phenolics.	Aroma and colour; no health effect shown. ¹⁴	Food analysis

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Liver injury from concentrated EGCG	UGT1A4 and COMT variants (secondary trial analysis); an immune-related gene variant (NCCIH)	Toxicology review: liver is the target organ in lab studies, tied to large single doses and fasting and to EGCG content. In a secondary trial analysis, women with the UGT1A4 A/C variant had larger ALT rises on high-dose extract. ^{8 2 28}	Lab and human
Caffeine plus L-theanine on attention	n/a	Cognitive benefits were seen with caffeine and L-theanine together and less with either alone. ¹⁵	Human review
Iron absorption	n/a	Tea polyphenols reduce absorption of non-haem iron in a dose-related way (radio-iron study of black and herb teas). ⁹	Human data
Acrylamide formation	n/a	Acrylamide forms from sugars and asparagine at high heat (EFSA). In roasted brown rice for tea, germinating first lowered acrylamide because of less asparagine (Kim 2021). ^{30 14}	Food chemistry

Absorption, metabolism and elimination

Absorption: Not covered in the sources read.
Distribution: Not covered.
Metabolism: A secondary trial analysis links the enzymes COMT and UGT1A4 with liver enzyme changes on high-dose extract.
Elimination: Not covered.
Bioavailability: Not covered.

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Isolated compounds versus whole extracts

Brewed tea, powdered leaf (matcha), liquid extracts and concentrated EGCG capsules are different products. EFSA estimates that supplements can deliver far more EGCG than infusions do; liver warnings come from the concentrated form. Genmaicha is a brewed drink that is part tea leaf and part roasted rice, and no study has measured how its contents compare with plain green tea.

Nutritional composition

Neither part is described as a source of essential nutrients in the sources read. The tea part contains caffeine, L-theanine, catechins and tannins. The roasted rice part holds starch, sugars and amino acids that change with roasting; how much reaches the drink is not stated.

9benefits and uses looked at

36studies and sources checked

Low certaintybest evidence rating found

6lab markers tracked in trials

5 low certainty1 very low certainty2 not enough evidence1 evidence against

What was looked at

The 9 benefits and uses checked for Genmaicha (Green Tea with Roasted Rice), each with how strong the evidence is. Tap one to open it.

Genmaicha itself (green tea with roasted rice)Not enough evidence
Cholesterol (green tea research)Low certainty
Blood pressure (green tea research)Low certainty
Body weight (green tea research)Low certainty
Cancer risk (green tea research)Not enough evidence
Heart disease and death rates in drinkers (green tea research)Low certainty
Attention, memory and mood (green tea research)Low certainty
Dementia and memory loss risk (green tea research)Very low certainty
Blood sugar in type 2 diabetes (green tea research)Evidence against

Lab markers tracked in the studies

LDL cholesterolSystolic blood pressureBody weightDeath from any causeHbA1cAttention and memory tests

What is Genmaicha (Green Tea with Roasted Rice) good for?

The main studied uses and how strong the human evidence is for each. "Low" is the best rating found for any benefit, and several are lower. All of it is about green tea, because genmaicha itself has not been studied. Genmaicha is not a replacement for medicine.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Genmaicha itself (green tea with roasted rice)

Not enough evidence

We found no trial of genmaicha and no human study of its roasted rice. Everything below is green tea research, which covers only the tea part of the blend.

1 studiesNot applicable.

Studies, doses and limits

What the trials found

PubMed searches for genmaicha found no clinical study of the drink. A search for roasted rice tea found food-chemistry papers (sugars, amino acids, acrylamide), not studies in people.

Results

No human results for genmaicha or for roasted rice tea.

Why this rating

No studies of the blend exist in the sources read.

Limits

Green tea results may not carry over to a blend that is part rice.

Why researchers looked

People drink genmaicha as an everyday green tea, so the natural question is whether it behaves like green tea.

Traditional use

Not described in the sources read.

Proposed mechanism Not established

No mechanism has been studied for genmaicha. The tea part contains catechins, caffeine and L-theanine; the roasted rice part is a cooked grain.

A proposed mechanism does not show that the effect happens in people.

See the Safety tab: caffeine from the tea part, acrylamide from roasting, and the usual green tea cautions.

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Cholesterol (green tea research)

Low certainty

These results are for green tea, not genmaicha. Pooled trials of green tea drinks and extracts show a small average fall in total and LDL cholesterol. Two reviews disagree, and most of the trial data comes from extract or mixed products, so the result for a cup of tea is uncertain. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

4 studiesMixed: drinks and extracts. Not a drink-only result.

Studies, doses and limits

What the trials found

A 2011 meta-analysis of 14 trials (1,136 people) of green tea drinks or extracts found a small fall in total and LDL cholesterol and no change in HDL. A Cochrane review of 7 green tea trials found larger falls that were not stable when checked. A 2020 review of 14 shorter trials of green or black tea (4 to 24 weeks) found no significant effect. NCCIH says most trials tested extract supplements, not the drink.

Results

Total cholesterol -7.20 mg/dL (95% CI -8.19 to -6.21) and LDL -2.19 mg/dL (-3.16 to -1.21) in the 2011 pooled trials; Cochrane green tea: total -0.62 mmol/L and LDL -0.64 mmol/L, not stable to sensitivity analysis; 2020 review: no significant change.

Effect sizes as reported

Small average falls; reviewers disagree on whether they are real in short trials.

Why this rating

Pooled drinks and extracts, small trials, results not stable, a later review found no effect.

Form and dose studied

Mixed: drinks and extracts. Not a drink-only result.

Who was studied

Healthy adults and adults at higher risk, mostly short trials.

Limits

Product types differ; most trials are short; no heart attack or stroke outcomes.

Why researchers looked

High LDL cholesterol is a risk factor for heart disease, and green tea catechins are often said to help.

Traditional use

Not described in the sources read.

Proposed mechanism Not established

No mechanism was established in the sources read.

A proposed mechanism does not show that the effect happens in people.

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Blood pressure (green tea research)

Low certainty

These results are for green tea, not genmaicha. Reviews find a very small average fall in blood pressure, with big differences between studies. One review of short trials found no effect. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

3 studiesGreen tea supplementation; the 2025 abstract does not separate drink …

Studies, doses and limits

What the trials found

A 2025 meta-analysis of 36 trials of green tea supplementation found average falls of about 1 mmHg in both systolic and diastolic pressure with very high differences between trials. The Cochrane review found larger falls (about 3 mmHg) from a small number of green tea trials that were not stable. A 2020 review of 14 trials of green or black tea (4 to 24 weeks) found no significant effect.

Results

Systolic -1.08 mmHg (95% CI -1.98 to -0.18), diastolic -1.09 mmHg (-1.67 to -0.50) in 36 trials; Cochrane green tea systolic -3.18 mmHg, diastolic -3.42 mmHg, unstable; 2020 review: no significant effect.

Effect sizes as reported

About 1 to 3 mmHg at most.

Why this rating

Very large differences between trials (I2 74 to 85 percent), unstable Cochrane result, one review with no effect.

Form and dose studied

Green tea supplementation; the 2025 abstract does not separate drink from extract.

Who was studied

Adults, with stronger effects in people who started with raised blood pressure.

Limits

Heterogeneity; mixed forms; small average change that may not matter to health.

Why researchers looked

High blood pressure is a leading risk factor for heart disease and stroke.

Traditional use

Not described in the sources read.

Proposed mechanism Not established

No mechanism was established in the sources read.

A proposed mechanism does not show that the effect happens in people.

Brewed green tea has no safety concerns reported in adults (NCCIH) but contains caffeine. Concentrated extract capsules are a different product with rare serious liver injury reports. See the Safety tab. The authors call green tea a complementary approach, not a treatment for high blood pressure.

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Body weight (green tea research)

Low certainty

These results are for green tea, not genmaicha. A Cochrane review found almost no weight loss from green tea outside Japan. The Japanese trials were too different to combine and ranged from little change to a few kilograms. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

2 studiesGreen tea preparations, drinks and extracts.

Studies, doses and limits

What the trials found

The review included trials of at least 12 weeks in overweight or obese adults: six outside Japan (532 people) and eight in Japan (1,030 people).

Results

Outside Japan: weight -0.04 kg (95% CI -0.5 to 0.4), BMI -0.2 kg/m2, waist -0.2 cm; none significant. Japanese trials ranged from -0.2 to -3.5 kg and could not be pooled.

Effect sizes as reported

No meaningful change outside Japan.

Why this rating

Short trials of 12 to 13 weeks, many preparation types, results differ by region.

Form and dose studied

Green tea preparations, drinks and extracts.

Who was studied

Overweight and obese adults.

Limits

Not a drink-only result; short.

Why researchers looked

Green tea contains catechins and caffeine, which reviewers say are believed to raise energy use.

Traditional use

NCCIH says green tea and extracts are promoted for weight loss.

Proposed mechanism Hypothesis

The Cochrane reviewers state a belief that catechins and caffeine may raise energy metabolism; they say the efficacy remains unclear.

A proposed mechanism does not show that the effect happens in people.

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Cancer risk (green tea research)

Not enough evidence

These results are for green tea, not genmaicha. A large Cochrane review found inconsistent, low-certainty results. It does not show that green tea prevents cancer. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

2 studiesExtract in trials; drinking in observational studies.

Studies, doses and limits

What the trials found

The review used 142 studies: 11 trials of green tea extract (1,795 people) and 131 observational studies (over 1,100,000 people).

Results

Extract trials: prostate cancer RR 0.50 (95% CI 0.18 to 1.36), gynaecological RR 1.50 (0.41 to 5.48), skin RR 1.00 (0.06 to 15.92). Observational highest versus lowest intake: cancer incidence RR 0.83 (0.65 to 1.07); cancer death RR 0.99 (0.91 to 1.07). Results conflicted between study designs for some cancers.

Effect sizes as reported

Intervals include no effect.

Why this rating

Low-certainty and inconsistent results; mostly observational; Asian populations.

Form and dose studied

Extract in trials; drinking in observational studies.

Who was studied

Adults, mostly in Asia.

Limits

Cannot show cause; trials used extract.

Why researchers looked

Lab studies have suggested catechins may slow cancer cell growth; population studies have asked whether tea drinkers get less cancer.

Traditional use

Not described in the sources read.

Proposed mechanism Lab only

Cochrane notes that laboratory studies have suggested catechins may inhibit cancer cell growth. This is lab work and not shown in people.

A proposed mechanism does not show that the effect happens in people.

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Heart disease and death rates in drinkers (green tea research)

Low certainty

These results are for green tea, not genmaicha. In Japan, people who drank five or more cups a day had somewhat lower death rates than people who drank less than one. This is an association and does not show tea caused it. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

2 studiesGreen tea as a drink.

Studies, doses and limits

What the trials found

A pooled analysis of eight Japanese cohorts followed 313,381 people for a mean 17.3 years.

Results

Five or more cups a day versus less than one: all-cause death HR 0.90 (0.87 to 0.94) in men and 0.82 (0.74 to 0.90) in women; heart disease HR 0.82 and 0.75; stroke-type HR 0.76 and 0.78. In women only, total cancer death HR 0.89 (0.83 to 0.96) at 1 to 2 cups.

Effect sizes as reported

Roughly 10 to 18 percent lower all-cause death among the heaviest drinkers.

Why this rating

Observational; healthier lifestyle among drinkers cannot be ruled out; Japanese data.

Form and dose studied

Green tea as a drink.

Who was studied

Japanese adults.

Limits

Self-reported intake; cannot show cause; may not apply outside Japan.

Why researchers looked

Green tea is part of daily life in Japan, so large cohorts can compare heavy and light drinkers.

Traditional use

NCCIH notes that lower heart disease risk has been linked to green tea in Asian but not Western groups.

Proposed mechanism Not established

Not established. Observational data cannot identify a mechanism.

A proposed mechanism does not show that the effect happens in people.

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Attention, memory and mood (green tea research)

Low certainty

These results are for green tea, not genmaicha. A systematic review found signs of better attention and memory and less anxiety, mostly in small or short studies. The effect seems to come from caffeine and L-theanine together. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

1 studiesGreen tea, green tea extract, L-theanine and EGCG.

Studies, doses and limits

What the trials found

Mancini 2017 reviewed 21 studies (4 randomised trials, 12 crossover studies, 4 cross-sectional studies, 1 cohort) on green tea, green tea extract, L-theanine and EGCG.

Results

The reviewers report evidence of less anxiety, better memory and attention and brain-scan changes with working memory. The abstract gives no numbers.

Effect sizes as reported

Not given in the abstract.

Why this rating

Mixed products (drink, extract, isolated L-theanine), many short or single-dose studies, no numbers in abstract.

Form and dose studied

Green tea, green tea extract, L-theanine and EGCG.

Who was studied

Mostly healthy adults.

Limits

Not a drink-only result; PubMed only; reviewers own quality scores.

Why researchers looked

Green tea contains caffeine and L-theanine, and people drink it for alertness with calm.

Traditional use

Not described in the sources read.

Proposed mechanism Human study observation

The reviewers say the effect cannot be put down to one ingredient: benefits for cognition appeared with caffeine and L-theanine together and were smaller with either alone.

A proposed mechanism does not show that the effect happens in people.

¹⁵

Dementia and memory loss risk (green tea research)

Very low certainty

These results are for green tea, not genmaicha. Observational studies lean towards lower risk in green tea drinkers, but they are few and mixed, and cannot show that tea is the reason. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

1 studiesGreen tea as a drink.

Studies, doses and limits

What the trials found

A 2019 systematic review found 3 cohort and 5 cross-sectional studies.

Results

One cohort and three cross-sectional studies supported a benefit, one cohort and one cross-sectional study partly supported it, and one of each found no link.

Effect sizes as reported

Not given in the abstract.

Why this rating

Eight observational studies, mixed results, cannot show cause.

Form and dose studied

Green tea as a drink.

Who was studied

Mostly Asian adults.

Limits

Observational; small number of studies.

Why researchers looked

Population studies in Asia asked whether regular green tea drinkers keep their memory longer.

Traditional use

Not described in the sources read.

Proposed mechanism Not established

Not established.

A proposed mechanism does not show that the effect happens in people.

¹³

Blood sugar in type 2 diabetes (green tea research)

Evidence against

These results are for green tea, not genmaicha. A meta-analysis of 14 trials found no significant effect of green tea supplements on blood sugar measures in people with type 2 diabetes. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.

1 studiesGreen tea supplementation; type not stated in the abstract.

Studies, doses and limits

What the trials found

A 2021 meta-analysis pooled 14 randomised trials in people with type 2 diabetes.

Results

No significant effect on fasting glucose, fasting insulin, HbA1c or insulin resistance (HOMA-IR).

Effect sizes as reported

No significant effect.

Why this rating

One meta-analysis of 14 trials found no effect; the abstract does not give the product type; small trials, so no effect is not proof of none.

Form and dose studied

Green tea supplementation; type not stated in the abstract.

Who was studied

Adults with type 2 diabetes.

Limits

Small trials; form unclear.

Why researchers looked

Catechins have been proposed to affect blood sugar and insulin.

Traditional use

Not described in the sources read.

Proposed mechanism Not established

Not established in the source read.

A proposed mechanism does not show that the effect happens in people.

Brewed green tea has no safety concerns reported in adults (NCCIH) but contains caffeine. Concentrated extract capsules are a different product with rare serious liver injury reports. See the Safety tab. People taking diabetes medicines should speak to their prescriber before using any supplement.

Connections to the rest of health

How Genmaicha (Green Tea with Roasted Rice) connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Heart Health		Not enough evidence	Genmaicha itself (green tea with roasted rice): We found no trial of genmaicha and no human study of its roasted rice. Everything below is green tea research, which covers only the tea part of the blend.	¹⁴
Energy Vitality		Not enough evidence	Genmaicha itself (green tea with roasted rice): We found no trial of genmaicha and no human study of its roasted rice. Everything below is green tea research, which covers only the tea part of the blend.	¹⁴
Cholesterol Balance		Low certainty	Cholesterol (green tea research): These results are for green tea, not genmaicha. Pooled trials of green tea drinks and extracts show a small average fall in total and LDL cholesterol. Two reviews disagree, and most of the trial data comes from extract or mixed products, so the result for a cup of tea is uncertain. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{25 6 10 28}
Heart Health		Low certainty	Cholesterol (green tea research): These results are for green tea, not genmaicha. Pooled trials of green tea drinks and extracts show a small average fall in total and LDL cholesterol. Two reviews disagree, and most of the trial data comes from extract or mixed products, so the result for a cup of tea is uncertain. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known. Blood pressure (green tea research): These results are for green tea, not genmaicha. Reviews find a very small average fall in blood pressure, with big differences between studies. One review of short trials found no effect. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{25 6 10 28 20}
Blood Pressure Support		Low certainty	Blood pressure (green tea research): These results are for green tea, not genmaicha. Reviews find a very small average fall in blood pressure, with big differences between studies. One review of short trials found no effect. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{20 6 10}
Weight Management		Low certainty	Body weight (green tea research): These results are for green tea, not genmaicha. A Cochrane review found almost no weight loss from green tea outside Japan. The Japanese trials were too different to combine and ranged from little change to a few kilograms. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{12 28}
Preventive Wellness		Not enough evidence	Cancer risk (green tea research): These results are for green tea, not genmaicha. A large Cochrane review found inconsistent, low-certainty results. It does not show that green tea prevents cancer. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{5 28}
Heart Health	Biological association	Low certainty	Heart disease and death rates in drinkers (green tea research): These results are for green tea, not genmaicha. In Japan, people who drank five or more cups a day had somewhat lower death rates than people who drank less than one. This is an association and does not show tea caused it. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{1 28}
Longevity	Biological association	Low certainty	Heart disease and death rates in drinkers (green tea research): These results are for green tea, not genmaicha. In Japan, people who drank five or more cups a day had somewhat lower death rates than people who drank less than one. This is an association and does not show tea caused it. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	^{1 28}
Mental Clarity		Low certainty	Attention, memory and mood (green tea research): These results are for green tea, not genmaicha. A systematic review found signs of better attention and memory and less anxiety, mostly in small or short studies. The effect seems to come from caffeine and L-theanine together. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹⁵
Better Focus		Low certainty	Attention, memory and mood (green tea research): These results are for green tea, not genmaicha. A systematic review found signs of better attention and memory and less anxiety, mostly in small or short studies. The effect seems to come from caffeine and L-theanine together. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹⁵
Memory Support		Low certainty	Attention, memory and mood (green tea research): These results are for green tea, not genmaicha. A systematic review found signs of better attention and memory and less anxiety, mostly in small or short studies. The effect seems to come from caffeine and L-theanine together. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹⁵
Brain Health		Low certainty	Attention, memory and mood (green tea research): These results are for green tea, not genmaicha. A systematic review found signs of better attention and memory and less anxiety, mostly in small or short studies. The effect seems to come from caffeine and L-theanine together. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹⁵
Brain Health	Biological association	Very low certainty	Dementia and memory loss risk (green tea research): These results are for green tea, not genmaicha. Observational studies lean towards lower risk in green tea drinkers, but they are few and mixed, and cannot show that tea is the reason. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹³
Healthy Aging	Biological association	Very low certainty	Dementia and memory loss risk (green tea research): These results are for green tea, not genmaicha. Observational studies lean towards lower risk in green tea drinkers, but they are few and mixed, and cannot show that tea is the reason. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	¹³
Blood Sugar Balance		Evidence against	Blood sugar in type 2 diabetes (green tea research): These results are for green tea, not genmaicha. A meta-analysis of 14 trials found no significant effect of green tea supplements on blood sugar measures in people with type 2 diabetes. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	³
Metabolic Health		Evidence against	Blood sugar in type 2 diabetes (green tea research): These results are for green tea, not genmaicha. A meta-analysis of 14 trials found no significant effect of green tea supplements on blood sugar measures in people with type 2 diabetes. Genmaicha is only partly tea leaf, so what this means for a cup of genmaicha is not known.	³

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Cardiovascular System	Biological association	Not enough evidence	Studied for: Genmaicha itself (green tea with roasted rice) Studied for: Cholesterol (green tea research)	^{14 25 6 10 28 20 1}
Metabolism Weight	Biological association	Low certainty	Studied for: Body weight (green tea research) Studied for: Blood sugar in type 2 diabetes (green tea research)	^{12 28 3}
Cellular	Biological association	Not enough evidence	Studied for: Cancer risk (green tea research)	^{5 28}
Brain Focus	Biological association	Low certainty	Studied for: Attention, memory and mood (green tea research) Studied for: Dementia and memory loss risk (green tea research)	^{15 13}

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Liver	Adverse effect or risk	Low certainty	Rare liver injury, mostly with extract; case reports and trials of high-dose EGCG. Preparation or compound: Concentrated green tea extract; rarely tea	^{17 4 19}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Pregnancy	Contraindication	Low certainty	Counts toward the caffeine limit. Preparation or compound: Green tea (caffeine)	^{29 28}
Iron-deficiency anemia	Adverse effect or risk	Very low certainty	Tea can lower iron absorption; one case report. Preparation or compound: Green tea drink	^{9 7}
Acrylamide from roasted food	Adverse effect or risk	Not enough evidence	Roasting forms acrylamide; EFSA links dietary acrylamide to possible cancer risk. No figure for a cup of genmaicha. Preparation or compound: Roasted rice and roasted tea (not measured in genmaicha)	^{30 22 14}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
LDL cholesterol	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{25 10 6}
Systolic blood pressure	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{20 10 6}
Body weight	Biological association	Low certainty	Measured in trials: unchanged. A lab change is not the same as a health benefit.	¹²
Death from any cause	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹
HbA1c	Biological association	Evidence against	Measured in trials: unchanged. A lab change is not the same as a health benefit.	³
Attention and memory tests	Biological association	Low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁵

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
UGT1A4	Preliminary mechanism	Human	Genotype linked with liver enzyme rises on high-dose extract in one secondary analysis.	²
COMT	Preliminary mechanism	Human	Genotype examined with liver enzyme changes on high-dose extract.	²

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Caffeine	Adverse effect or risk	Moderate certainty	Counts toward daily caffeine; see FDA and NHS figures. Preparation or compound: Green tea	^{27 29}
Epigallocatechin gallate (EGCG)	Biological association	Human	Liver effects at high supplement doses; other actions not established in the sources read. Preparation or compound: Leaf	^{32 4}
Caffeine	Biological association	Human	Stimulant; see Safety tab. Preparation or compound: Leaf	^{33 27}
L-theanine	Biological association	Human	Reviewers link benefits for attention to caffeine and L-theanine together. Preparation or compound: Leaf	^{34 15 16}
Tannins and other polyphenols	Biological association	Human	Tea polyphenols lower iron absorption (radio-iron study, black and herb teas). Preparation or compound: Leaf and stem	^{16 9}
Acrylamide	Biological association	Food analysis and regulator	EFSA: dietary acrylamide potentially increases cancer risk. Preparation or compound: Roasted grain and roasted tea	^{30 22 18 24 14}
Rice starch, sugars, amino acids and phenolics (after roasting)	Biological association	Food analysis	Aroma and colour; no health effect shown. Preparation or compound: Roasted rice grain	¹⁴

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 4 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Metabolic1 Other21

The evidence

The research centre for Genmaicha (Green Tea with Roasted Rice). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We built this page from our green tea profile, whose PubMed abstracts were read on 2026-10-25, and searched PubMed for genmaicha and roasted rice tea. We found no clinical study of either, and four food-chemistry papers on acrylamide and roasted grain (abstracts read). The NCCIH and EFSA acrylamide pages were read in full; LiverTox and LactMed were read only as PubMed summary records. Plant names were checked in GBIF. Certainty ratings are the compiler's own reading. No funding statement was read for most papers, so industry links are not ruled out.

Study library: every study we checked 36

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Abe 2019 Green tea consumption and mortality in Japanese men and women: a pooled analysis of eight population-based cohort studies in Japan European Journal of Epidemiology · PMID 31392470 · DOI	Pooled cohort	313381 313,381 Japanese adults in eight cohorts; 52,943 deaths over a mean 17.3 years	Green tea drinking (self-reported) leaf (drink) Five or more cups a day versus less than one Mean follow-up 17.3 years · vs Drinking less than 1 cup a day	Five or more cups a day versus less than one: all-cause death HR 0.90 (95% CI 0.87 to 0.94) in men and 0.82 (0.74 to 0.90) in women; heart disease HR 0.82 (0.75 to 0.90) men, 0.75 (0.68 to 0.84) women; stroke-type (cerebrovascular) HR 0.76 (0.68 to 0.85) men, 0.78 (0.68 to 0.89) women. In women, total cancer death HR 0.89 (0.83 to 0.96) at 1 to 2 cups and 0.91 (0.85 to 0.98) at 3 to 4 cups. Lower death rates among heavy green tea drinkers (an association) (All-cause HR 0.90 (0.87, 0.94) men; 0.82 (0.74, 0.90) women) Methods, limits and funding Outcomes: Deaths from all causes, heart disease, stroke, cancer, respiratory disease Limitations: Observational: tea drinkers may differ in diet, exercise and health; Japanese data may not apply elsewhere Funding and conflicts: Not stated in the abstract Read: abstract
Acosta 2023 Hepatotoxicity with High-Dose Green Tea Extract: Effect of Catechol-O-Methyltransferase and Uridine 5-Diphospho-glucuronosyltransferase 1A4 Genotypes Journal of Dietary Supplements · PMID 36178169 · DOI	Controlled trial	1075 Postmenopausal women in the Minnesota Green Tea Trial (400 in the extract group), mean age 59.8 years	High-dose green tea extract capsules (843 mg/day EGCG) versus placebo capsules extract 843 mg/day EGCG 12 months · vs Placebo capsules	This is a secondary analysis. In the extract group, women with the UGT1A4 (rs6755571) A/C variant had larger rises in ALT (about +78% and +82% at months 6 and 9) than women with C/C (about +28% and +30%). The authors suggest this variant may be a risk factor for meaningful liver enzyme rises with 6 to 9 months of high-dose extract. Genes may affect who gets liver enzyme rises on high-dose extract (ALT change differences p<0.001 and p=0.004 (months 6 and 9)) Methods, limits and funding Outcomes: Liver enzymes by gene variant Limitations: Secondary analysis; mostly white women; extract only; not about tea Funding and conflicts: Not stated in the abstract Read: abstract
Asbaghi 2021 Effect of green tea on glycemic control in patients with type 2 diabetes mellitus: A systematic review and meta-analysis Diabetes & Metabolic Syndrome · PMID 33285391 · DOI	Meta-analysis	14 randomised trials in people with type 2 diabetes	Green tea supplementary intake Differed Differed · vs Control	Supplementary green tea had no significant effect on fasting glucose, fasting insulin, HbA1c or HOMA-IR. No significant effect found Methods, limits and funding Outcomes: Fasting glucose, fasting insulin, HbA1c, HOMA-IR Limitations: Small trials; the abstract does not say whether the trials used drink or extract; no effect found is not proof of no effect Funding and conflicts: Not stated in the abstract Read: abstract
EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) 2018 Scientific opinion on the safety of green tea catechins EFSA Journal · PMID 32625874 · DOI	Regulatory opinion	Review of published studies, authority reports and submitted data	Green tea infusions, reconstituted drinks and food supplements containing catechins leaf (drink) and extract Mean EGCG intake from infusions in the EU 90 to 300 mg/day (up to 866 mg/day for high-level drinkers); supplements 5 to 1,000 mg/day	Catechins from traditionally prepared green tea infusions, and reconstituted drinks of the same composition, are in general considered safe at the intakes reported in EU countries. Rare cases of liver injury have been reported after infusions, most probably an idiosyncratic (individual) reaction. Clinical trials show that EGCG at or above 800 mg a day taken as a food supplement raised liver enzymes (serum transaminases) compared with control. Drink generally safe at usual intakes; high-dose supplements raise liver enzymes Methods, limits and funding Outcomes: Liver safety of catechins (EGCG) Limitations: Abstract only was read; the full opinion could not be opened Funding and conflicts: Regulator opinion Read: abstract
Filippini 2020 Green tea (Camellia sinensis) for the prevention of cancer Cochrane Database of Systematic Reviews · PMID 32118296 · DOI	Systematic review	142 studies: 11 randomised trials (1795 people, green tea extract versus placebo) and 131 observational studies (over 1,100,000 people)	Green tea extract in trials; drinking green tea in observational studies leaf (drink) and extract Differed Differed · vs Placebo (trials); lowest intake (cohorts)	Trials of extract (low-certainty): prostate cancer RR 0.50 (95% CI 0.18 to 1.36), gynaecological cancer RR 1.50 (0.41 to 5.48), non-melanoma skin cancer RR 1.00 (0.06 to 15.92). Observational, highest versus lowest intake: overall cancer incidence RR 0.83 (0.65 to 1.07, three studies); cancer death RR 0.99 (0.91 to 1.07, eight studies); both low-certainty. Results conflicted by study design for oesophageal, prostate and urinary cancers and leukaemia. The authors call the evidence limited and inconsistent. Extract side effects included stomach and gut problems, raised liver enzymes and, more rarely, insomnia, raised blood pressure and skin reactions. No clear effect on cancer risk; inconsistent (Prostate RR 0.50 (0.18, 1.36); cancer incidence RR 0.83 (0.65, 1.07); cancer mortality RR 0.99 (0.91, 1.07)) Methods, limits and funding Outcomes: Cancer incidence and death, adverse effects, quality of life Limitations: Most studies in Asian populations who drink a lot of green tea; observational studies cannot prove cause; trials used extract Funding and conflicts: Non-US government support listed in PubMed record Read: abstract
Hartley 2013 Green and black tea for the primary prevention of cardiovascular disease Cochrane Database of Systematic Reviews · PMID 23780706 · DOI	Systematic review	821 11 randomised trials of at least 3 months in healthy adults or adults at high risk of heart disease; 7 trials tested green tea, 4 black tea	Green tea, black tea or tea extracts (doses and forms differed between trials) leaf (drink) and extracts Differed between trials At least 3 months · vs No intervention, placebo or minimal intervention	No trial reported heart or blood vessel events. Green tea: total cholesterol -0.62 mmol/L (95% CI -0.77 to -0.46), LDL cholesterol -0.64 mmol/L (-0.77 to -0.52), systolic blood pressure -3.18 mmHg (-5.25 to -1.11), diastolic -3.42 (-4.54 to -2.30). The authors say only a small number of studies contributed and the green tea results were not stable to sensitivity analysis. Adverse events in five trials were judged unlikely to be due to the tea. Small lowering of cholesterol and blood pressure, unstable (TC MD -0.62 (-0.77, -0.46); LDL MD -0.64 (-0.77, -0.52); SBP MD -3.18 (-5.25, -1.11)) Methods, limits and funding Outcomes: Heart disease events, blood pressure, cholesterol Limitations: Few trials per analysis, risk of bias, forms and doses mixed (drink and extract); no long-term follow-up Funding and conflicts: Non-US government support listed in PubMed record; no industry funding stated in the abstract Read: abstract
He 2024 Severe iron-deficiency anemia after short-term moderate consumption of green tea in woman: A rare case report Heliyon · PMID 39263133 · DOI	Case report	1 One woman who drank moderate amounts of green tea for about three months	Green tea drink leaf (drink) Moderate (amount not given in the abstract) About 3 months	Haemoglobin fell by 6.9 g/dl with severe iron-deficiency anemia. After she changed her tea habits there was no recurrence. The authors say clinicians should know even moderate tea intake can cause severe anemia in people who are especially vulnerable to its effect on iron absorption. One reported case of severe anemia Methods, limits and funding Outcomes: Haemoglobin Limitations: Single case; other causes of iron loss are not described in the abstract Funding and conflicts: Not stated Read: abstract
Hu 2018 The safety of green tea and green tea extract consumption in adults - Results of a systematic review Regulatory Toxicology and Pharmacology · PMID 29580974 · DOI	Systematic review	Toxicology studies and adverse-event data from 159 human intervention studies	Brewed green tea, green tea in drinks or food, and concentrated catechin-rich preparations leaf (drink) and extract	Liver was the target organ. Liver adverse events in humans came from a limited range of concentrated, catechin-rich preparations taken as large single doses, and not from brewed tea or extracts used in drinks or food. The authors derived a safe intake level for adults for solid single-dose preparations and a separate, higher observed safe level for beverage forms (the numbers are in the paper). Liver effects tied to concentrated bolus-dose preparations, not brewed tea Methods, limits and funding Outcomes: Liver adverse events Limitations: Abstract only was read; the abstract does not state who funded the review Funding and conflicts: Funding and conflict-of-interest statement not read Read: abstract
Hurrell 1999 Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages British Journal of Nutrition · PMID 10999016	Controlled trial	Adult volunteers given a bread meal with radio-labelled iron	Black tea, herb teas (chamomile, vervain, lime flower, pennyroyal, peppermint), coffee and cocoa leaf (drink) Test beverages with different polyphenol amounts Single meals · vs Water control meal	All the beverages reduced iron absorption in a way that depended on their polyphenol content. Black tea cut absorption by 79 to 94 percent, peppermint tea 84, pennyroyal 73, cocoa 71, vervain 59, lime flower 52 and camomile 47 percent. Milk made little difference. Green tea was NOT tested. Large drop in iron absorption from a meal Methods, limits and funding Outcomes: Iron absorption from the meal Limitations: Green tea not tested; single meals in adults; applying this to green tea is an inference Funding and conflicts: Non-US government support listed in PubMed record Read: abstract
Igho-Osagie 2020 Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Journal of Nutrition · PMID 33188386 · DOI	Meta-analysis	798 14 randomised trials in healthy adults and at-risk adults (obesity, prediabetes, borderline high cholesterol, metabolic syndrome)	Green tea or black tea leaf (drink) Differed 4 to 24 weeks (mean 7.4) · vs Placebo or control	No significant effect of tea on systolic or diastolic blood pressure, total, LDL or HDL cholesterol or triglycerides. Strength of evidence was low to moderate because the studies were small and underpowered. No significant effect in short trials (No significant effects (intervals not given in the abstract)) Methods, limits and funding Outcomes: Blood pressure, total, LDL and HDL cholesterol, triglycerides Limitations: Small trials, short duration, green and black tea pooled; absence of effect is not proof of no effect Funding and conflicts: Non-US government support listed in PubMed record Read: abstract
Jayasingha 2025 Fluoride in tea: accumulation, dietary exposure, and future strategies for risk mitigation in food safety; a scoping review Critical Reviews in Food Science and Nutrition · PMID 40504749 · DOI	Scoping review lab/food analysis	88 studies worldwide on fluoride in tea	Tea (all types) leaf (drink)	Tea plants take up fluoride from soil. Longer brewing released more fluoride. Average levels by type were brick tea 4.78 mg/L, black tea 2.73, green tea 1.37, white tea 0.49 and herbal tea 0.17. The review says black tea poses risks for children and for adults in high-intake regions; excessive intake may cause tooth and bone fluorosis and kidney disease. Green tea has less fluoride than black or brick tea but more than white or herbal tea Methods, limits and funding Outcomes: Fluoride in brewed tea Limitations: Scoping review; averages mix many countries; local water also adds fluoride Funding and conflicts: Not stated Read: abstract
Jurgens 2012 Green tea for weight loss and weight maintenance in overweight or obese adults Cochrane Database of Systematic Reviews · PMID 23235664 · DOI	Systematic review	Randomised trials of at least 12 weeks in overweight or obese adults; six trials outside Japan (532 people) and eight in Japan (1030 people)	Green tea preparations (drink and extracts) leaf (drink) and extracts Differed 12 to 13 weeks · vs Control	Outside Japan: weight difference -0.04 kg (95% CI -0.5 to 0.4), BMI -0.2 kg/m2 (-0.5 to 0.1), waist -0.2 cm (-1.4 to 0.9). The eight Japanese trials were too different to pool; weight differences ranged from -0.2 to -3.5 kg. Adverse events in four of eight trials that recorded them were mild to moderate; two needing hospital care were reported as not related. Almost no weight change outside Japan; mixed results in Japanese trials (Weight MD -0.04 kg (-0.5, 0.4) outside Japan) Methods, limits and funding Outcomes: Weight, BMI, waist circumference, adverse events Limitations: Short trials; green tea preparations of many kinds; not a drink-only result Funding and conflicts: Non-US government support listed in PubMed record Read: abstract
Kakutani 2019 Green Tea Intake and Risks for Dementia, Alzheimer's Disease, Mild Cognitive Impairment, and Cognitive Impairment: A Systematic Review Nutrients · PMID 31137655 · DOI	Systematic review	3 cohort studies and 5 cross-sectional studies	Green tea drinking leaf (drink) · vs Lower or no intake	One cohort and three cross-sectional studies supported a benefit, one cohort and one cross-sectional partly supported it, and one cohort and one cross-sectional found no association. The authors say well-designed cohort studies are needed. Mixed observational results Methods, limits and funding Outcomes: Dementia, Alzheimer disease, mild cognitive impairment, cognitive impairment Limitations: Observational only; small number of studies; cannot show cause Funding and conflicts: Not stated in the abstract Read: abstract
Kim 2021 Effects of germination and roasting on physicochemical and sensory characteristics of brown rice for tea infusion. Food Chemistry · PMID 33618097 · DOI	Food analysis food	Brown rice, germinated or not, roasted to make a rice tea (lab study)	Brown rice (Oryza sativa) roasted grain	Roasting produced volatile compounds and phenolics. Acrylamide in roasted germinated brown rice was significantly lower than in roasted ungerminated brown rice because it had less asparagine. Germination raised free amino acids, reducing sugars and phenolics. Roasted brown rice for tea contains acrylamide; germinating first lowered it Methods, limits and funding Outcomes: Sugars, amino acids, phenolics, acrylamide, sensory quality Limitations: Lab food study; no acrylamide figures in the abstract; not a trial in people; one company author affiliation. Funding and conflicts: One author lists a food company affiliation (Food Research Institute, Dongsuh Companies Inc.) Read: abstract
Mancini 2017 Green tea effects on cognition, mood and human brain function: A systematic review Phytomedicine · PMID 28899506 · DOI	Systematic review	21 studies: 4 randomised trials, 12 crossover studies, 4 cross-sectional studies and 1 cohort	Green tea, green tea extract, L-theanine or EGCG leaf (drink), extract and isolated compounds Differed Differed · vs Differed	The reviewers found evidence that green tea influences psychological symptoms (for example less anxiety), cognition (for example memory and attention) and brain function (for example working-memory activation on brain scans). Benefits on cognition were seen with caffeine and L-theanine together, with less effect from either alone, so the effect cannot be put down to one ingredient. Possible small effects on attention and memory Methods, limits and funding Outcomes: Anxiety and mood, memory and attention, brain activity Limitations: Mixes drink, extract and isolated compounds; many short or single-dose studies; PubMed only; quality scores are the reviewers own Funding and conflicts: Not stated in the abstract Read: abstract
NICHD / 2006 Drugs and Lactation Database (LactMed): Green Tea LactMed (NCBI Bookshelf) · PMID 30000907	Database record	n/a	Green tea leaves and stems leaf and stem	Green tea leaves and stems contain caffeine, L-theanine, polyphenols and tannins. Fussiness, jitteriness and poor sleep have been reported in infants of mothers with extremely high caffeine intakes. Giving tea directly to infants can interfere with iron absorption and cause anemia, but anemia in breastfed infants has not been reported with maternal tea intake. Passage of L-theanine into breastmilk has not been studied. No studies of oral green tea extract in breastfeeding were found. No clear harm from usual maternal tea intake; caution at very high caffeine Methods, limits and funding Outcomes: Breastfeeding safety Limitations: Summary record; no new data Funding and conflicts: Public database Read: abstract
NIDDK 2012 LiverTox: Green Tea (Clinical and Research Information on Drug-Induced Liver Injury) LiverTox (NCBI Bookshelf) · PMID 31643260	Database record	n/a	Green tea extract and, more rarely, large amounts of green tea leaf and extract	Green tea extract and, more rarely, ingestion of large amounts of green tea have been implicated in cases of clinically apparent acute liver injury, including instances of acute liver failure and either need for urgent liver transplantation or death. Rare but serious liver injury, mostly with extract Methods, limits and funding Outcomes: Drug-induced liver injury Limitations: Only the PubMed summary was read; the full LiverTox page was not opened Funding and conflicts: Public database Read: abstract
Ono 2003 Analysis of acrylamide by LC-MS/MS and GC-MS in processed Japanese foods. Food Additives and Contaminants · PMID 12623644 · DOI	Food analysis food	63 63 processed Japanese food samples covering 31 product types	Processed foods roasted barley grains for mugi-cha tea; rice crackers	Roasted barley grains for mugi-cha tea contained 200 to 600 micrograms per kg of acrylamide. Rice crackers processed by grilling or frying were lower than potato crisps. The authors say acrylamide formation is strongly influenced by processing conditions. Acrylamide in roasted barley tea grain 200 to 600 micrograms per kg Methods, limits and funding Outcomes: Acrylamide level in foods Limitations: Roasted barley, not rice; dry grain, not a brewed drink. Funding and conflicts: Government institute; no industry funding stated in the abstract Read: abstract
Pillukat 2014 Concentrated green tea extract induces severe acute hepatitis in a 63-year-old woman - a case report with pharmaceutical analysis Journal of Ethnopharmacology · PMID 24862489 · DOI	Case report	1 A 63-year-old woman taking green tea capsules on the advice of a cancer support group	Concentrated green tea extract capsules (EGCG 93.2% of the catechins found) extract Very high EGCG dose level per the analysis	Severe hepatitis assessed as probably caused by the capsules (CIOMS/RUCAM score). The liver tissue pattern fit drug-induced hepatitis and other causes were excluded. After stopping, and a treatment called albumin dialysis, she recovered quickly and fully. Lab analysis of the capsules found no contaminants. Severe but reversible liver injury linked to concentrated extract Methods, limits and funding Outcomes: Liver injury Limitations: Single case; extract, not brewed tea Funding and conflicts: Not stated Read: abstract
Rezaei 2025 Effect of green tea supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomised controlled trials Blood Pressure · PMID 40497293 · DOI	Meta-analysis	36 randomised trials in adults	Green tea supplementation (forms not broken out in the abstract) Not given here Studies of 8 weeks or less showed stronger effects · vs Control or placebo	Systolic blood pressure fell by 1.08 mmHg (95% CI -1.98 to -0.18; I2 85%) and diastolic by 1.09 mmHg (-1.67 to -0.50; I2 74%). Effects were stronger in people with raised starting blood pressure, shorter studies, Asian populations and women. No clear link between size of change and dose or duration. The authors call green tea a complementary approach, not a treatment. Very small average blood pressure drop with large differences between studies (SBP -1.08 (-1.98, -0.18); DBP -1.09 (-1.67, -0.50)) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure Limitations: Very high heterogeneity; the abstract does not separate drink from extract; the GRADE rating is not given in the abstract Funding and conflicts: Not stated in the abstract Read: abstract
Rodriguez 2020 Human exposure to fluoride from tea (Camellia sinensis) in a volcanic region - Canary Islands, Spain Environmental Science and Pollution Research · PMID 32740848 · DOI	Food analysis lab/food analysis	90 90 tea samples (Canary Islands)	Mixed, black and other teas prepared with local tap water leaf (drink) Two 250 mL cups a day assumed	Mixed teas (2.82 mg/L) and black teas (2.28 mg/L) had the highest fluoride. Two daily cups of those teas made with local tap water would give children aged 4 to 8 a large share (74.4% and 63.6%) of the EFSA upper intake level. The authors advise less tea for children and in pregnancy. Fluoride in tea can matter for young children in some regions Methods, limits and funding Outcomes: Fluoride in tea Limitations: Local water and region; green tea results are not given in the abstract Funding and conflicts: Not stated Read: abstract
Takatsuki 2003 Determination of acrylamide in processed foods by LC/MS using column switching. Shokuhin Eiseigaku Zasshi · PMID 12846155 · DOI	Food analysis food	Processed and cooked foods bought in Japanese retail markets, including roasted barley tea (mugi-cha) and roasted green tea (hoji-cha)	Roasted foods dried roasted product (not a brewed drink)	Roasted foods (roasted sesame seed, roasted barley mugi-cha, roasted tea hoji-cha, coffee beans, curry powder) contained 116 to 567 ng/g of acrylamide. Potato chips and French fries were higher (467 to 3,544 ng/g). Foods with much water tended to be lower than dry foods. Acrylamide found in roasted tea and roasted barley Methods, limits and funding Outcomes: Acrylamide level in foods Limitations: Measured the dry roasted product, not a brewed cup; roasted rice or genmaicha were not named in the abstract. Funding and conflicts: Government institute method paper; no industry funding stated in the abstract Read: abstract
Taylor 1999 Probable antagonism of warfarin by green tea Annals of Pharmacotherapy · PMID 10332534 · DOI	Case report	1 A 44-year-old man with a mechanical aortic heart valve taking warfarin	Green tea drink leaf (drink) Half a gallon to a gallon of green tea a day for about a week About 1 week before the low reading	The INR fell from 3.79 to 1.37 about three weeks later, and was 1.14 a month after. He had started drinking one-half to one gallon of green tea a day about a week before the INR of 1.37. After stopping the tea the INR rose to 2.55. The authors suggested vitamin K in the tea. A drop in warfarin effect linked in time to a very large amount of green tea (INR 3.79 to 1.37) Methods, limits and funding Outcomes: Blood clotting test (INR) Limitations: One case; cannot prove cause; very large amount of tea; vitamin K content was not measured Funding and conflicts: Not stated Read: abstract
Yoshida 2005 Acrylamide in Japanese processed foods and factors affecting acrylamide level in potato chips and tea. Advances in Experimental Medicine and Biology · PMID 16438315 · DOI	Food analysis food	Processed foods sold in Japanese markets; roasted green tea	Processed foods, roasted green tea roasted green tea leaf	Rice crackers and candied sweet potatoes were under 350 micrograms per kg. The abstract says roasting time and temperature affect acrylamide in roasted green tea, but gives no figures. Roasting time and temperature change acrylamide in roasted green tea Methods, limits and funding Outcomes: Acrylamide level and what changes it Limitations: Abstract gives no tea figures; not about genmaicha or roasted rice. Funding and conflicts: Government institute; no industry funding stated in the abstract Read: abstract
Zheng 2011 Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials American Journal of Clinical Nutrition · PMID 21715508 · DOI	Meta-analysis	1136 14 randomised trials in adults	Green tea beverage or green tea extract leaf (drink) and extract Differed Differed · vs Control	Total cholesterol lowered by 7.20 mg/dL (95% CI -8.19 to -6.21) and LDL cholesterol by 2.19 mg/dL (-3.16 to -1.21); HDL cholesterol did not change significantly. The authors say changes were not influenced by type of intervention, dose, duration, health status or study quality. Small average drop in total and LDL cholesterol (TC -7.20 (-8.19, -6.21) mg/dL; LDL -2.19 (-3.16, -1.21) mg/dL) Methods, limits and funding Outcomes: Total, LDL and HDL cholesterol Limitations: Mixes drinks and extracts; the abstract gives no separate drink-only result; later reviews found no effect in short trials (see Igho-Osagie 2020) Funding and conflicts: Non-US government support listed in PubMed record; funding details not in the abstract Read: abstract
n/a 2016 IARC (WHO): Press release no. 244, coffee, mate and very hot beverages (15 June 2016) n/a · Source	Authoritative guidance n/a	n/a	n/a	IARC classified drinking very hot beverages as probably carcinogenic to humans (Group 2A), based on limited evidence from studies in places where tea or mate is drunk very hot, and said it is the temperature rather than the drink that appears responsible. Methods, limits and funding Outcomes: IARC classified drinking very hot beverages as probably carcinogenic to humans (Group 2A), based on limited evidence from studies in places where tea or mate is drunk very hot, and said it is the temperature rather than the drink that appears responsible. Limitations: Press release read from the PDF on 2026-10-25; the exact temperature figure could not be read from the extracted text, so it is not quoted here. Read: full-text
n/a 2024 FDA: Spilling the Beans: How Much Caffeine Is Too Much? (content current as of 28 Aug 2024) n/a · Source	Authoritative guidance n/a	n/a	n/a	Lists green tea at 37 mg caffeine per 12 fl oz drink. Cites 400 mg a day as an amount not generally linked with negative effects in most adults, with wide differences in sensitivity. Lists signs of too much caffeine (faster heart rate, palpitations, high blood pressure, insomnia, anxiety, jitters, upset stomach, nausea, headache). Says caffeinated drinks should be avoided for children younger than age 2 (quoting the Dietary Guidelines) and that pregnant or breastfeeding people should talk to a health professional. Methods, limits and funding Outcomes: Lists green tea at 37 mg caffeine per 12 fl oz drink. Cites 400 mg a day as an amount not generally linked with negative effects in most adults, with wide differences in sensitivity. Lists signs of too much caffeine (faster heart rate, palpitations, high blood pressure, insomnia, anxiety, jitters, upset stomach, nausea, headache). Says caffeinated drinks should be avoided for children younger than age 2 (quoting the Dietary Guidelines) and that pregnant or breastfeeding people should talk to a health professional. Limitations: Consumer guidance page, not a trial. Read in full on 2026-10-25. Read: full-text
n/a 2025 NCCIH (NIH): Green Tea: Usefulness and Safety (last updated February 2025) n/a · Source	Authoritative guidance n/a	n/a	n/a	Says definite conclusions cannot yet be reached on whether green tea helps for most uses. Cancer results inconsistent; lower heart disease risk seen in Asian but not Western groups; small cholesterol drops mostly from extract trials; no safety concerns reported for green tea as a drink in adults; liver injury uncommon and mostly with extract tablets or capsules; interactions with nadolol (high-dose green tea), atorvastatin (extract) and raloxifene; keep caffeine moderate in pregnancy. Methods, limits and funding Outcomes: Says definite conclusions cannot yet be reached on whether green tea helps for most uses. Cancer results inconsistent; lower heart disease risk seen in Asian but not Western groups; small cholesterol drops mostly from extract trials; no safety concerns reported for green tea as a drink in adults; liver injury uncommon and mostly with extract tablets or capsules; interactions with nadolol (high-dose green tea), atorvastatin (extract) and raloxifene; keep caffeine moderate in pregnancy. Limitations: A regulator-style fact sheet, not a trial. Page text read in full on 2026-10-25. Read: full-text
n/a 2026 NHS (UK): Foods to avoid in pregnancy (page last reviewed 15 June 2026) n/a · Source	Authoritative guidance n/a	n/a	n/a	Says you should not have more than 200 mg of caffeine a day in pregnancy, estimates about 75 mg in a cup of tea such as black or green tea, and says too much caffeine has been linked to a higher chance of miscarriage and stillbirth. Methods, limits and funding Outcomes: Says you should not have more than 200 mg of caffeine a day in pregnancy, estimates about 75 mg in a cup of tea such as black or green tea, and says too much caffeine has been linked to a higher chance of miscarriage and stillbirth. Limitations: Public-health guidance, not a trial. Read in full on 2026-10-25. The per-cup figure is an estimate. Read: full-text
n/a 2026 EFSA: Acrylamide topic page (read 2026-10-25) n/a · Source	Authoritative guidance n/a	n/a	n/a	Acrylamide forms naturally in starchy foods during high-temperature cooking, including roasting, through the Maillard reaction (sugars with the amino acid asparagine). EFSA found it in potato crisps, French fries, bread, biscuits and coffee. In 2015 EFSA published its first full risk assessment, and experts concluded that acrylamide in food potentially increases the risk of developing cancer for consumers in all age groups. Methods, limits and funding Outcomes: Acrylamide forms naturally in starchy foods during high-temperature cooking, including roasting, through the Maillard reaction (sugars with the amino acid asparagine). EFSA found it in potato crisps, French fries, bread, biscuits and coffee. In 2015 EFSA published its first full risk assessment, and experts concluded that acrylamide in food potentially increases the risk of developing cancer for consumers in all age groups. Limitations: Regulator web page, read in full on 2026-10-25. It does not name tea or rice. Read: full-text
n/a 2026 EMA: Camelliae sinensis non fermentatum folium (green tea), herbal medicinal product page n/a · Source	Authoritative guidance n/a	n/a	n/a	Page lists Camellia sinensis (L.) Kuntze, non fermentatum folium (green tea), therapeutic area "Fatigue and weakness", status "Assessment finalised", outcome "European Union herbal monograph". Documents: final EU herbal monograph (EMA/HMPC/283630/2012, published 29 April 2014), assessment report and an addendum to the assessment report (EMA/HMPC/30571/2022, published 26 September 2022). Methods, limits and funding Outcomes: Page lists Camellia sinensis (L.) Kuntze, non fermentatum folium (green tea), therapeutic area "Fatigue and weakness", status "Assessment finalised", outcome "European Union herbal monograph". Documents: final EU herbal monograph (EMA/HMPC/283630/2012, published 29 April 2014), assessment report and an addendum to the assessment report (EMA/HMPC/30571/2022, published 26 September 2022). Limitations: Only the web page was read. The monograph and assessment-report PDFs were not opened, so the wording of the monograph is NOT verified. Read: abstract
n/a 2026 PubChem: epigallocatechin gallate (CID 65064), formula C22H18O11 n/a · Source	Database record n/a	n/a	n/a	Compound record confirmed through the PubChem API on 2026-10-25. Methods, limits and funding Outcomes: Compound record confirmed through the PubChem API on 2026-10-25. Limitations: Database record only. Read: full-text
n/a 2026 PubChem: caffeine (CID 2519), formula C8H10N4O2 n/a · Source	Database record n/a	n/a	n/a	Compound record confirmed through the PubChem API on 2026-10-25. Methods, limits and funding Outcomes: Compound record confirmed through the PubChem API on 2026-10-25. Limitations: Database record only. Read: full-text
n/a 2026 PubChem: L-theanine (CID 439378), formula C7H14N2O3 n/a · Source	Database record n/a	n/a	n/a	Compound record confirmed through the PubChem API on 2026-10-25. Methods, limits and funding Outcomes: Compound record confirmed through the PubChem API on 2026-10-25. Limitations: Database record only. Read: full-text
n/a 2026 GBIF Backbone Taxonomy: Camellia sinensis (L.) Kuntze (usage key 3189635), retrieved 2026-10-25 n/a · Source	Database record n/a	n/a	n/a	Accepted species, family Theaceae, order Ericales, genus Camellia. Synonyms listed by the API include Camellia bohea (L.) Sweet, Camellia chinensis (Sims) Kuntze and Camellia cantonensis Lour. Methods, limits and funding Outcomes: Accepted species, family Theaceae, order Ericales, genus Camellia. Synonyms listed by the API include Camellia bohea (L.) Sweet, Camellia chinensis (Sims) Kuntze and Camellia cantonensis Lour. Limitations: Taxonomic database record via the GBIF API. Read: full-text
n/a 2026 GBIF Backbone Taxonomy: Oryza sativa L. (usage key 2703459), retrieved 2026-10-25 n/a · Source	Database record n/a	n/a	n/a	GBIF accepts Oryza sativa L., family Poaceae (the grass family), as the species name for cultivated rice. Methods, limits and funding Outcomes: GBIF accepts Oryza sativa L., family Poaceae (the grass family), as the species name for cultivated rice. Limitations: Taxonomy lookup only; says nothing about the tea. Read: full-text

What we do not know yet

No trial or human study of genmaicha, or of roasted rice tea, was found.
No measurement of caffeine, catechins or acrylamide in genmaicha or in a brewed cup was found.
Acrylamide figures read are for dry roasted barley and roasted green tea, not roasted rice.
Green tea trials mostly mix drinks and extracts, so results cannot be assigned to a cup of tea.
Most population data come from Japan and China; results may not apply elsewhere.
No measured lead, cadmium, arsenic, aluminium or pesticide values were found; the EMA monograph and LiverTox full text were not opened.
No source on the history of the blend was read.

How new research is added

New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating or safety wording. New publications never change ratings automatically.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Metabolic 3

▼

LDL cholesterol

Lowered in trials

The cholesterol carried in the blood that is linked with higher heart disease risk.

Low certainty

Results and what it means

Why it was measured

To see whether green tea changes blood fats.

Statistical vs. clinical meaning

Small and inconsistent; a lab number, not a heart outcome.

Safety implication

None from the numbers; see the Safety tab for extract risks.

Study	Result	People	Product
²⁵	LDL -2.19 mg/dL (95% CI -3.16 to -1.21)	Adults in 14 trials	Green tea drinks or extracts
¹⁰	No significant change in LDL	798 people in 14 trials	Green or black tea, 4 to 24 weeks

^{25 10 6}

●

Body weight

Unchanged in trials

Weight in kilograms.

Low certainty

Results and what it means

Why it was measured

To see whether green tea helps with weight loss.

Statistical vs. clinical meaning

No meaningful change outside Japan.

Safety implication

None.

Study	Result	People	Product
¹²	-0.04 kg (95% CI -0.5 to 0.4) outside Japan; -0.2 to -3.5 kg in Japanese trials, not pooled	Overweight adults, 12 to 13 weeks	Green tea preparations

¹²

●

HbA1c

Unchanged in trials

A blood test that shows average blood sugar over about three months.

Evidence against

Results and what it means

Why it was measured

To see whether green tea helps people with type 2 diabetes.

Statistical vs. clinical meaning

No effect found.

Safety implication

None.

Study	Result	People	Product
³	No significant effect on HbA1c, fasting glucose, insulin or HOMA-IR	14 trials in type 2 diabetes	Green tea supplementation

Other 3

▼

Systolic blood pressure

Lowered in trials

The top number in a blood pressure reading.

Low certainty

Results and what it means

Why it was measured

To see whether green tea changes blood pressure.

Statistical vs. clinical meaning

Very small and varied.

Safety implication

None from the numbers.

Study	Result	People	Product
²⁰	-1.08 mmHg (95% CI -1.98 to -0.18)	36 trials in adults	Green tea supplementation
¹⁰	No significant change	798 people in 14 trials	Green or black tea, 4 to 24 weeks

^{20 10 6}

▼

Death from any cause

Lowered in trials

The risk of dying from any cause during follow-up.

Low certainty

Results and what it means

Why it was measured

To see whether heavy green tea drinkers live longer.

Statistical vs. clinical meaning

Observational association only.

Safety implication

None.

Study	Result	People	Product
¹	HR 0.90 (0.87 to 0.94) men; 0.82 (0.74 to 0.90) women, 5+ cups a day versus under 1	313,381 Japanese adults	Self-reported green tea drinking

▲

Attention and memory tests

Raised in trials

Scores on computer or paper tests of attention and working memory.

Low certainty

Results and what it means

Why it was measured

To see whether green tea affects thinking.

Statistical vs. clinical meaning

Possible small effect.

Safety implication

None.

Study	Result	People	Product
¹⁵	Reviewers report better memory and attention with caffeine and L-theanine together; no numbers in the abstract	21 mixed studies	Green tea, extract, L-theanine, EGCG

¹⁵

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 8

Caffeine comes from the tea part. Genmaicha is made with green tea leaf, so it contains caffeine. We found no measurement of caffeine in genmaicha, and the rice adds none. For green tea, the FDA says about 400 mg a day from all sources is not generally linked with harm in most adults, and that too much can cause fast heartbeat, poor sleep, anxiety, jitters, upset stomach and headache. Sensitivity differs a lot between people. Authoritative guidance ²⁷
Roasted rice and acrylamide. Roasting starchy grain makes acrylamide, a chemical that forms from sugars and the amino acid asparagine at high heat (EFSA). In 2015 EFSA concluded that acrylamide in food potentially increases cancer risk for consumers of all ages. Japanese food analyses found acrylamide in roasted barley tea grain and in roasted green tea, and a lab study found it in roasted brown rice for tea. We found no measurement in genmaicha itself or in a brewed cup, so how much reaches the drink is unknown. Food analysis ^{30 22 18 24 14}
Tea and a green tea extract capsule are not the same thing. NCCIH reports no safety concerns for green tea drunk as a beverage by adults, apart from its caffeine. Genmaicha is a drink, not an extract. Liver injury is uncommon but has been reported, mostly with concentrated extract in tablets or capsules. EFSA judged traditionally prepared green tea infusions generally safe at the intakes seen in Europe, and found that high-dose EGCG supplements raised liver enzymes in trials. Do not carry safety or benefit results from one form to the other. Authoritative guidance ^{28 4 8}
Rare liver injury, mostly with extract. LiverTox says green tea extract, and more rarely large amounts of green tea, have been linked to clinically apparent liver injury, including liver failure needing transplant or ending in death. EFSA noted rare cases after infusions too, probably an individual reaction. A case report describes severe hepatitis from concentrated extract capsules that cleared after stopping them. Anyone with liver disease, or who has had liver trouble from a supplement, should ask a clinician before any extract. Case report ^{17 4 19}
Pregnancy, breastfeeding and young children. The NHS says not to have more than 200 mg of caffeine a day in pregnancy. NCCIH says to keep caffeine moderate in pregnancy and to ask your provider. LactMed reports fussiness, jitteriness and poor sleep in infants only with extremely high maternal caffeine, and says tea given directly to infants can interfere with iron absorption and cause anemia. The FDA quotes the Dietary Guidelines that caffeinated drinks should be avoided for children younger than age 2. Authoritative guidance ^{29 28 16 27}
Iron. Polyphenols in tea cut iron absorption from a meal in a radio-iron study, but that study did not test green tea. A 2024 case report describes severe iron-deficiency anemia in a woman after about three months of moderate green tea. If you have low iron or anemia, ask a clinician about tea around meals. Human study ^{9 7}
Medicines. NCCIH says high doses of green tea lowered blood levels of the heart medicine nadolol, green tea extract lowered levels of atorvastatin, and an NCCIH-funded study showed an interaction with raloxifene. One 1999 case report links very large amounts of green tea with weaker warfarin effect. Ask your pharmacist if you take any regular medicine. Authoritative guidance ^{28 23}
Very hot drinks. IARC classed drinking very hot beverages as probably carcinogenic to humans (Group 2A) for oesophageal cancer and said it is the temperature, not the drink, that appears responsible. This applies to hot tea as to any other very hot drink; letting a cup cool is a sensible step. Authoritative guidance ²⁶

Side effects 7

Effect	How often	Severity and recovery	Evidence
Caffeine effects (fast heartbeat, jitters, poor sleep, upset stomach) Listed by the FDA as signs of too much caffeine from any source.	Depends on how much caffeine you take and how sensitive you are; no rate in the sources read	mild to moderate Reversible when caffeine is cut back	Authoritative guidance ²⁷
Acrylamide intake from roasted grain A long-term, cancer-risk concern from food in general (EFSA), not a reaction you would notice after a cup.	No figure for genmaicha	not stated not applicable	Regulator statement ^{30 22}
Nausea, constipation, stomach discomfort and higher blood pressure (extract) NCCIH lists these for green tea extract supplements.	No rate in the sources read	mild Reversible after stopping (not stated)	Authoritative guidance ²⁸
Gut problems, raised liver enzymes, insomnia, raised blood pressure, skin reactions (extract) Cochrane lists these as adverse effects of green tea extract in trials.	Not given in the abstract	mild to moderate Not given	Systematic review ⁵
Liver injury (mostly extract; rarely tea) High-dose extract raised liver enzymes in trials (EFSA, abstract).	Uncommon; no rate found	severe Mostly recovery after stopping; some cases need transplant or are fatal	Case report ^{28 17 19 4}
Lower iron absorption; anemia in a vulnerable person Green tea was not tested in the radio-iron study.	One case report	moderate to severe Improved after changing tea habits	Case report ^{9 7}
Fluoride intake from tea Green tea averaged 1.37 mg/L in a scoping review, below black and brick tea; the risk discussed is mainly for children and heavy drinkers.	Depends on tea type, brewing time and local water	not stated not stated	Food analysis ^{11 21}

Liver

Liver injury linked to green tea is rare and mostly linked to concentrated extract capsules or tablets. LiverTox says extract, and more rarely very large amounts of tea, have been implicated in acute liver injury, including liver failure needing transplant or death. EFSA found raised liver enzymes with high-dose EGCG supplements in trials and noted rare liver injury after infusions, most probably an unusual individual reaction. A systematic review of 159 human studies found liver events came from concentrated, catechin-rich preparations taken in large single doses, not from brewed tea or extracts used in drinks or food. NCCIH says people with a specific immune-related gene variant seem especially susceptible, and a secondary analysis of a one-year extract trial found liver enzyme rises differed by gene variant. ^{17 4 8 19 2 28}

How often. No rate in tea drinkers or extract users could be found in the sources read.

Monitoring. No monitoring advice was read from an agency. The Safety tab tells readers to stop extract and seek care if liver warning signs appear.

p24862489.

This is a safety connection. It is not evidence that Genmaicha (Green Tea with Roasted Rice) supports liver health.

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Warfarin prescription	The case authors suggested vitamin K in the tea could counter warfarin; vitamin K was not measured.	One 1999 case report: INR fell from 3.79 to 1.37 after about a week of half a gallon to a gallon of green tea a day, and rose to 2.55 after stopping. It cannot prove cause and the amount was very large.	Case report Very low certainty ²³	Tell your prescriber about any big change in tea habits so your INR can be checked.
Nadolol (beta-blocker) prescription	Not described in the source read.	NCCIH says green tea at high doses reduced blood levels of nadolol and so its effectiveness.	Authoritative guidance Low certainty ²⁸	Ask your pharmacist if you take nadolol.
Atorvastatin (cholesterol medicine) prescription	Not described in the source read.	NCCIH says green tea extract can reduce blood levels of atorvastatin. This is about the extract.	Authoritative guidance Low certainty ²⁸	Ask your pharmacist before taking green tea extract with a statin.
Raloxifene (bone medicine) prescription	Not described in the source read.	NCCIH says a study it funded showed an interaction between green tea and raloxifene. Details were not given.	Authoritative guidance Low certainty ²⁸	Ask your pharmacist.
Iron supplements and iron-poor diets supplement	Tea polyphenols reduce iron absorption in general.	A radio-iron study showed black tea and herb teas cut iron absorption; green tea was not tested, and one case report links moderate green tea with severe anemia.	Human study Low certainty ^{9 7}	If you have low iron, ask a clinician about drinking tea away from meals. Whether that works was not tested in the sources read.
Other sources of caffeine food	Caffeine adds up across coffee, other teas, energy drinks and some supplements.	The FDA says its 400 mg figure is for all caffeine in a day.	Authoritative guidance Moderate certainty ^{27 29}	Count all caffeine sources, especially in pregnancy.

Who should check first 7

Situation	Advice	Evidence
Pregnancy	Green tea is not banned in pregnancy, but it counts toward the daily caffeine limit. No source read covers green tea extract capsules in pregnancy, so ask a clinician before using them.	Authoritative guidance ^{29 28}
Breastfeeding	LactMed reports infant fussiness and poor sleep only with extremely high maternal caffeine. No studies of green tea extract in breastfeeding were found.	Authoritative guidance ¹⁶
Infants and young children	Do not give tea to infants. LactMed says it can interfere with iron absorption and cause anemia. Avoid caffeinated drinks for children under 2 (FDA, quoting the Dietary Guidelines).	Authoritative guidance ^{16 27}
Liver disease or past liver injury from a supplement	Ask a clinician before using green tea extract capsules or tablets, because of the liver injury reports. The sources read do not give a rule for brewed tea in liver disease.	Precaution from liver reports ^{17 4}
Low iron or anemia	Ask a clinician. Tea can lower iron absorption.	Human study ^{9 7}
Taking warfarin, nadolol, a statin or raloxifene	Ask your pharmacist or prescriber before changing how much green tea or extract you take.	Authoritative guidance ^{23 28}
Allergy or intolerance to rice or tea	No source read covers allergy to genmaicha. If you react to rice or to tea, avoid it and ask a doctor.	Precaution

Overdose, product quality and regulators

Summary. Brewed green tea has no safety concerns reported for adults (NCCIH). The main toxicity concern is the liver, linked to concentrated catechin-rich extract taken in large single doses.

Animal. The Hu systematic review says lab studies show the liver as target organ, strongly tied to dosing conditions such as a large single dose by gavage and fasting, and to total catechin and EGCG content.

Human doses studied. EFSA found that high-dose EGCG taken as a food supplement raised liver enzymes in trials (the threshold is in the opinion). The Minnesota Green Tea Trial gave a high-dose extract for 12 months.

High dose or long term signals. Liver enzyme rises with long high-dose extract use; differences by gene variant in one secondary analysis.

Overdose response. Not described in the sources read.

Genotoxicity. Not read.

Toxic or hazardous parts. Leaf is the part used; stems are also in tea (LactMed). No source read compared other parts.

Quality was checked for fluoride and for acrylamide from roasting. Sources read gave no measured lead, cadmium, arsenic, aluminium or pesticide values for genmaicha, green tea or roasted rice tea, so that is unknown here, not shown safe.

Acrylamide from roasting. Acrylamide forms when starchy grain is roasted (EFSA). Roasted barley tea grain held 200 to 600 micrograms per kg and roasted foods including hoji-cha and mugi-cha 116 to 567 ng/g in Japanese analyses; a lab study of roasted brown rice tea found acrylamide too, and less when the rice was germinated first. These are dry roasted products, not brewed cups, and none is genmaicha. ^{30 22 18 14 24}

Fluoride. Tea leaves take up fluoride. A scoping review of 88 studies gave average levels of brick tea 4.78 mg/L, black tea 2.73, green tea 1.37, white tea 0.49 and herbal tea 0.17; longer brewing released more. A Canary Islands study found black and mixed teas could give children aged 4 to 8 a large share of the EFSA upper limit; the abstract did not give green tea. ^{11 21}

Heavy metals and pesticides. Not found in the sources read for green tea. Not described is not proof of none.

Supplement quality. LactMed notes that dietary supplements are not pre-approved by the FDA and labelled and actual ingredients and amounts can differ. In the case report, lab analysis of the capsules found no contaminants but a very high EGCG level. ^{16 19}

Body	Action	Date
EFSA (European Union)	Acrylamide topic page: forms in starchy foods during roasting and other high-heat cooking; the 2015 risk assessment concluded dietary acrylamide potentially increases cancer risk in all age groups. It does not name genmaicha, tea or rice. source	2015 (risk assessment); page read 2026-10-25
NCCIH (NIH) (United States)	Says no safety concerns have been reported for green tea as a beverage in adults; lists extract side effects, rare liver injury, medicine interactions and a caffeine caution in pregnancy. Notes the FDA has approved a specific green tea extract ointment as a prescription drug for genital warts (a topical drug, not a drink or supplement). source	2025-02
EFSA (European Union)	Opinion on safety of green tea catechins: infusions prepared the traditional way are in general considered safe at EU intakes; rare liver injury after infusions; high-dose EGCG supplements raised liver enzymes in trials. source	2018-04
EMA / HMPC (European Union)	Has a final EU herbal monograph and assessment report for Camellia sinensis non fermentatum folium (green tea); EMA page lists the therapeutic area as "Fatigue and weakness". source	2014-04-29 (monograph); 2022-09-26 (assessment addendum)
NICHD LactMed (United States)	Notes caffeine-related infant fussiness only at extremely high maternal intake; tea directly to infants can cause anemia; no oral extract data in breastfeeding. source	2006
NHS (United Kingdom)	Pregnancy: no more than 200 mg of caffeine a day. source	2026-06-15
US FDA (United States)	Caffeine consumer update: 400 mg a day not generally associated with harm in most adults; lists signs of too much caffeine. source	2024-08-28
IARC (WHO) (International)	Very hot beverages probably carcinogenic to humans (Group 2A); temperature, not the drink, appears responsible. source	2016-06-15

When to get medical help

Yellow skin or eyes, dark urine, pale stools, strong tiredness, itching or pain in the upper right belly while using green tea extract: stop it and get medical care now.
Chest pain, a racing or irregular heartbeat, fainting: call emergency services.
Black stools, unusual bruising or bleeding if you take warfarin: contact your prescriber or emergency services.
Very pale skin, breathlessness or marked tiredness in someone who drinks a lot of tea and has low iron: see a clinician.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is genmaicha?

Genmaicha is green tea blended with roasted rice. The tea part is the leaf of Camellia sinensis, steamed or pan fried and dried but not fermented. The rice part is the roasted grain of Oryza sativa. We found no studies of the blend itself.

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Does genmaicha have caffeine?

Yes, from its green tea leaf. The rice has none. We found no measurement of caffeine in genmaicha. The FDA says about 400 mg a day from all sources is not generally linked with harm in most adults, with wide differences in sensitivity. Count all your caffeine, especially in pregnancy.

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Does the roasted rice add any health benefit?

Not shown. We found no human study of roasted rice tea. The studies we found are food-chemistry work on sugars, amino acids and acrylamide in roasted brown rice. Any benefit would have to come from the tea part, and even that evidence is weak.

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Is genmaicha the same as green tea extract?

No. A cup of tea is a weak water extract of the leaf. Capsules and tablets are concentrated catechins and have been linked to rare serious liver injury. NCCIH reports no safety concerns for the tea drink in adults. Do not carry safety or benefit results from one to the other.

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Is there acrylamide in genmaicha?

Probably some, but nobody has measured it. Roasting starchy grain forms acrylamide, and Japanese analyses found it in roasted barley tea grain and roasted green tea. A lab study found it in roasted brown rice for tea, and less when the rice was germinated first. EFSA says acrylamide in food potentially increases cancer risk for all ages.

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Does green tea lower cholesterol, blood pressure or weight?

Maybe slightly for cholesterol and blood pressure. A 2011 pooled analysis found small falls in total and LDL cholesterol, and a 2025 review of 36 trials found about 1 mmHg lower blood pressure, with big differences between trials. A 2020 review of short tea trials found no effect. A Cochrane review found almost no weight change outside Japan. None of this is about genmaicha, and most trials mix drinks and extracts.

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Does green tea prevent cancer or help people live longer?

This has not been shown. A Cochrane review of 142 studies found limited, inconsistent, low-certainty evidence on cancer. In Japan, people who drank five or more cups a day had lower all-cause and heart death rates than those who drank less than one cup. This is an association and may reflect other habits. None of it is about genmaicha.

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Does green tea help focus, memory or mood?

A review of 21 mostly small studies reported better attention and memory and less anxiety, mainly from caffeine and L-theanine together. It mixes drinks, extracts and single compounds, so certainty is low. Observational data on dementia are mixed and very low certainty. Genmaicha was not studied.

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Does green tea help with diabetes?

A meta-analysis of 14 trials found no significant effect of green tea supplements on fasting glucose, insulin or HbA1c in people with type 2 diabetes. Talk to your doctor before changing diabetes care.

Can green tea hurt the liver?

The drink rarely does. NCCIH reports no safety concerns for the beverage in adults, and liver injury is mostly linked to extract capsules and tablets. EFSA noted rare cases after infusions, likely an individual reaction. Stop any extract and get medical care if you notice yellow skin or eyes or dark urine.

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Is genmaicha safe in pregnancy, breastfeeding or for children?

Genmaicha has caffeine from its tea part, so it counts toward your daily limit. The NHS says no more than 200 mg of caffeine a day in pregnancy. LactMed reports infant fussiness only at extremely high maternal caffeine. Do not give tea to infants, and the FDA quotes guidance to avoid caffeinated drinks for children under 2. Ask a clinician about extract capsules.

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Does genmaicha affect iron or interact with medicines?

Tea polyphenols lowered iron absorption from a meal in a lab study (green tea was not tested), and a 2024 case report links moderate green tea with severe iron-deficiency anemia. NCCIH says high doses of green tea lowered blood levels of nadolol, and one 1999 case report links very large amounts of green tea with a weaker warfarin effect. Ask your pharmacist or prescriber.

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We built this page from our green tea profile, whose PubMed abstracts were read on 2026-10-25, and searched PubMed for genmaicha and roasted rice tea. We found no clinical study of either, and four food-chemistry papers on acrylamide and roasted grain (abstracts read). The NCCIH and EFSA acrylamide pages were read in full; LiverTox and LactMed were read only as PubMed summary records. Plant names were checked in GBIF. Certainty ratings are the compiler's own reading. No funding statement was read for most papers, so industry links are not ruled out.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. This page is information, not a recommendation to drink or take anything.

Sources 36

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Abe SK, Saito E, Sawada N, et al. Green tea consumption and mortality in Japanese men and women: a pooled analysis of eight population-based cohort studies in Japan. European Journal of Epidemiology. 2019. PMID 31392470. DOI 10.1007/s10654-019-00545-y. (abstract)
Acosta L, Byham-Gray L, Kurzer M, et al. Hepatotoxicity with High-Dose Green Tea Extract: Effect of Catechol-O-Methyltransferase and Uridine 5-Diphospho-glucuronosyltransferase 1A4 Genotypes. Journal of Dietary Supplements. 2023. PMID 36178169. DOI 10.1080/19390211.2022.2128501. (abstract)
Asbaghi O, Fouladvand F, Gonzalez MJ, et al. Effect of green tea on glycemic control in patients with type 2 diabetes mellitus: A systematic review and meta-analysis. Diabetes & Metabolic Syndrome. 2021. PMID 33285391. DOI 10.1016/j.dsx.2020.11.004. (abstract)
EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), Younes M, Aggett P, et al. Scientific opinion on the safety of green tea catechins. EFSA Journal. 2018. PMID 32625874. DOI 10.2903/j.efsa.2018.5239. (abstract)
Filippini T, Malavolti M, Borrelli F, et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020. PMID 32118296. DOI 10.1002/14651858.CD005004.pub3. (abstract)
Hartley L, Flowers N, Holmes J, et al. Green and black tea for the primary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews. 2013. PMID 23780706. DOI 10.1002/14651858.CD009934.pub2. (abstract)
He Y, Chen J. Severe iron-deficiency anemia after short-term moderate consumption of green tea in woman: A rare case report. Heliyon. 2024. PMID 39263133. DOI 10.1016/j.heliyon.2024.e36666. (abstract)
Hu J, Webster D, Cao J, et al. The safety of green tea and green tea extract consumption in adults - Results of a systematic review. Regulatory Toxicology and Pharmacology. 2018. PMID 29580974. DOI 10.1016/j.yrtph.2018.03.019. (abstract)
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. British Journal of Nutrition. 1999. PMID 10999016. (abstract)
Igho-Osagie E, Cara K, Wang D, et al. Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of Nutrition. 2020. PMID 33188386. DOI 10.1093/jn/nxaa295. (abstract)
Jayasingha H, Amarasooriya G, Rajapaksha N, et al. Fluoride in tea: accumulation, dietary exposure, and future strategies for risk mitigation in food safety; a scoping review. Critical Reviews in Food Science and Nutrition. 2025. PMID 40504749. DOI 10.1080/10408398.2025.2516756. (abstract)
Jurgens TM, Whelan AM, Killian L, et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database of Systematic Reviews. 2012. PMID 23235664. DOI 10.1002/14651858.CD008650.pub2. (abstract)
Kakutani S, Watanabe H, Murayama N. Green Tea Intake and Risks for Dementia, Alzheimer's Disease, Mild Cognitive Impairment, and Cognitive Impairment: A Systematic Review. Nutrients. 2019. PMID 31137655. DOI 10.3390/nu11051165. (abstract)
Kim HJ, Han JA, Lim ST, et al. Effects of germination and roasting on physicochemical and sensory characteristics of brown rice for tea infusion.. Food Chemistry. 2021. PMID 33618097. DOI 10.1016/j.foodchem.2021.129240. (abstract)
Mancini E, Beglinger C, Drewe J, et al. Green tea effects on cognition, mood and human brain function: A systematic review. Phytomedicine. 2017. PMID 28899506. DOI 10.1016/j.phymed.2017.07.008. (abstract)
NICHD / NLM. Drugs and Lactation Database (LactMed): Green Tea. LactMed (NCBI Bookshelf). 2006. PMID 30000907. (abstract)
NIDDK. LiverTox: Green Tea (Clinical and Research Information on Drug-Induced Liver Injury). LiverTox (NCBI Bookshelf). 2012. PMID 31643260. (abstract)
Ono H, Chuda Y, Ohnishi-Kameyama M, et al. Analysis of acrylamide by LC-MS/MS and GC-MS in processed Japanese foods.. Food Additives and Contaminants. 2003. PMID 12623644. DOI 10.1080/0265203021000060887. (abstract)
Pillukat MH, Bester C, Hensel A, et al. Concentrated green tea extract induces severe acute hepatitis in a 63-year-old woman - a case report with pharmaceutical analysis. Journal of Ethnopharmacology. 2014. PMID 24862489. DOI 10.1016/j.jep.2014.05.015. (abstract)
Rezaei M, Akhavan N, Fathi F, et al. Effect of green tea supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomised controlled trials. Blood Pressure. 2025. PMID 40497293. DOI 10.1080/08037051.2025.2517122. (abstract)
Rodriguez I, Burgos A, Rubio C, et al. Human exposure to fluoride from tea (Camellia sinensis) in a volcanic region - Canary Islands, Spain. Environmental Science and Pollution Research. 2020. PMID 32740848. DOI 10.1007/s11356-020-10319-9. (abstract)
Takatsuki S, Nemoto S, Sasaki K, et al. Determination of acrylamide in processed foods by LC/MS using column switching.. Shokuhin Eiseigaku Zasshi. 2003. PMID 12846155. DOI 10.3358/shokueishi.44.89. (abstract)
Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Annals of Pharmacotherapy. 1999. PMID 10332534. DOI 10.1345/aph.18238. (abstract)
Yoshida M, Ono H, Chuda Y, et al. Acrylamide in Japanese processed foods and factors affecting acrylamide level in potato chips and tea.. Advances in Experimental Medicine and Biology. 2005. PMID 16438315. DOI 10.1007/0-387-24980-X_31. (abstract)
Zheng XX, Xu YL, Li SH, et al. Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials. American Journal of Clinical Nutrition. 2011. PMID 21715508. DOI 10.3945/ajcn.110.010926. (abstract)
n/a. IARC (WHO): Press release no. 244, coffee, mate and very hot beverages (15 June 2016). n/a. 2016. (full-text)
n/a. FDA: Spilling the Beans: How Much Caffeine Is Too Much? (content current as of 28 Aug 2024). n/a. 2024. (full-text)
n/a. NCCIH (NIH): Green Tea: Usefulness and Safety (last updated February 2025). n/a. 2025. (full-text)
n/a. NHS (UK): Foods to avoid in pregnancy (page last reviewed 15 June 2026). n/a. 2026. (full-text)
n/a. EFSA: Acrylamide topic page (read 2026-10-25). n/a. 2026. (full-text)
n/a. EMA: Camelliae sinensis non fermentatum folium (green tea), herbal medicinal product page. n/a. 2026. (abstract)
n/a. PubChem: epigallocatechin gallate (CID 65064), formula C22H18O11. n/a. 2026. (full-text)
n/a. PubChem: caffeine (CID 2519), formula C8H10N4O2. n/a. 2026. (full-text)
n/a. PubChem: L-theanine (CID 439378), formula C7H14N2O3. n/a. 2026. (full-text)
n/a. GBIF Backbone Taxonomy: Camellia sinensis (L.) Kuntze (usage key 3189635), retrieved 2026-10-25. n/a. 2026. (full-text)
n/a. GBIF Backbone Taxonomy: Oryza sativa L. (usage key 2703459), retrieved 2026-10-25. n/a. 2026. (full-text)

Where to buy

Check the label first. Whatever you buy, look for these:

The herb is the first or only ingredient
Organic or lab-tested if that matters to you
Loose leaf or tea bags, and how long they have been stored
If you take medicines or are pregnant, ask a pharmacist about the herb first

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.