Anemia and Iron Deficiency: Tiredness and Testing

Q: Does being tired mean I have low iron?

No. Tiredness has many causes, including poor sleep, sleep apnea, diabetes and an overactive thyroid. Only a blood test can show whether iron or red blood cells are low.

Q: How are anemia and iron deficiency tested?

A clinician usually orders a blood test called a full or complete blood count, and may also check hemoglobin, blood iron and ferritin. A newer 2026 hematology guideline sets ferritin thresholds so iron deficiency can be diagnosed even without anemia.

Q: What causes iron deficiency anemia?

NHS names heavy periods and pregnancy as very common causes, and bleeding in the stomach or bowel as another. Diets low in iron, trouble absorbing iron (for example with celiac disease) and some medicines can also play a part. If the reason is unclear a clinician may test further.

Q: Can I take iron for energy without a test?

It is better to test first. Iron has side effects, too much iron can harm people with conditions such as haemochromatosis, and NHLBI says iron is generally not given to people who are not iron deficient. Anemia can also be a sign of another problem.

Q: Does iron help tiredness when I am not anemic?

In women with unexplained tiredness and low ferritin, trials found iron reduced self-rated tiredness a little more than placebo, but not measured fitness. In one trial only women with ferritin at or below 50 micrograms per liter improved, which is why testing comes first.

Q: How long does iron treatment take?

When prescribed for iron deficiency anemia, NHS says tablets are usually taken for about 6 months, with repeat blood tests to check levels return to normal.

Q: Do vegetarians need to worry about iron?

Iron from plant foods is harder to absorb than iron from meat, and a 2010 review estimates 5 to 12 percent absorption on vegetarian diets versus 14 to 18 percent on mixed diets in people with no iron stores. A clinician or dietitian can advise if you are concerned.

Q: Does vitamin C help iron work?

Vitamin C-rich foods help the body absorb iron, but adding vitamin C to iron pills raised hemoglobin only 0.14 g/dL in a 2024 review, which the authors called small and not clinically important.

Anemia and iron deficiency (blood conditions) · also called Anemia, anaemia, iron deficiency, iron deficiency anemia, low iron, low hemoglobin, anemia ferropénica, deficiencia de hierro

Anemia means having fewer healthy red blood cells than normal, so the body gets less oxygen-rich blood, and iron deficiency anemia is the most common type. Tiredness is only one possible sign and has many causes, so testing (a blood count and ferritin) comes before iron pills. Iron pills help when tests show low iron; the evidence for iron when you are not anemic is limited to small gains in self-rated tiredness in women with low ferritin. See a doctor if tiredness lasts a few weeks, or for black stools, chest pain or fainting.

General information, not medical advice. Last substantive update October 31, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Anemia and Iron Deficiency: Tiredness and Testing

Anemia means the blood has fewer healthy red blood cells than normal, and iron deficiency anemia is the most common type. Tiredness is only one possible sign, so a blood test comes before iron pills. Iron helps when tests show it is low, but iron for tiredness when you are not anemic has only limited evidence, and too much iron can harm. See a doctor if tiredness lasts a few weeks or other warning signs appear.

What anemia and iron deficiency are

NHLBI says anemia develops when your blood produces a lower-than-normal amount of healthy red blood cells, so your body does not get enough oxygen-rich blood. The lack of oxygen can make you feel tired or weak. Iron deficiency anemia, caused by too little iron, is the most common type; other types include vitamin B12-deficiency and hemolytic anemia.

A 2021 Lancet review adds that iron deficiency can cause problems before anemia appears. This page is educational. Only a clinician can tell whether you have anemia, and why.

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Why tiredness alone cannot tell you

The NHS lists tiredness and lack of energy, shortness of breath, noticeable heartbeats, paler skin and headaches as symptoms of iron deficiency anemia. NHLBI and MedlinePlus say mild anemia may cause no symptoms at all, and that symptoms usually develop slowly.

Many other conditions cause the same feelings. The NHS lists sleep apnea, diabetes, an overactive thyroid and ME/CFS among them, so a blood test, not symptoms alone, shows whether anemia is present.

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Why the cause matters

NHLBI says anemia may come from diet, medicines or another medical condition, and may be a sign of something more serious such as bleeding in the stomach, kidney disease, cancer or an autoimmune disease. NHS names heavy periods and pregnancy as very common causes of iron deficiency anemia, and bleeding in the stomach and bowel as another.

MedlinePlus lists poor absorption (for example from celiac disease, Crohn disease or stomach surgery) and not eating enough iron-containing foods as other reasons. A British guideline says about a third of men and postmenopausal women with iron deficiency anemia have an underlying abnormality, most often in the gut, so finding the cause matters as much as replacing iron.

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How anemia and iron deficiency are tested

The usual first test is a full or complete blood count, which shows whether the number of red blood cells and the hemoglobin are normal. NHLBI says a clinician may also check blood iron and ferritin. A Cochrane review found a ferritin cutoff of 30 micrograms per liter was reasonably sensitive and very specific for iron deficiency in people seeking medical care, though ferritin also rises with inflammation.

A 2026 American Society of Hematology guideline sets ferritin thresholds for different groups so that iron deficiency can be diagnosed whether or not anemia is present. Testing comes before iron pills because tiredness has many causes, and because iron is generally not given to people who are not iron deficient.

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What established care looks like

When a blood test shows low red blood cells, NHS says iron tablets are recommended, usually for about 6 months, with repeat blood tests to check levels return to normal. NHLBI describes other options in general terms, such as iron given through a vein, medicines for anemia caused by kidney disease and, for serious anemia, blood transfusion. A clinician chooses among them.

Common side effects of iron tablets include constipation or diarrhea, stomach pain, heartburn, nausea and darker stools. Untreated iron deficiency anemia can raise the risk of infection and heart or lung complications, and carries risks in pregnancy (NHS). Talk to a clinician before starting or stopping any treatment.

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Food and iron

Good iron sources include red meat, beans, nuts, dried fruit and fortified breakfast cereals; dark-green leafy vegetables also appear on NHS lists. MedlinePlus says iron from plants and supplements is harder to absorb and that vitamin C-rich foods help absorption. NHS says most people can get the iron they need from a varied, balanced diet.

In a meal study, black tea, coffee, cocoa and herbal teas such as peppermint and chamomile all lowered iron absorption. NHS lists tea, coffee, dairy and high-phytate foods among things to have less of when iron is low.

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What natural and lifestyle approaches have and have not shown

Iron when you are not anemic: in women with unexplained tiredness and low ferritin, trials found a little less self-rated tiredness with iron than with placebo, but no better measured fitness. Vitamin C added to iron raised hemoglobin only slightly, and two small trials found alternate-day iron was absorbed better and caused fewer gut side effects. A review of iron cooking pots was mixed.

No randomised trial of a herbal or 'blood-building' product for anemia was read. Natural does not automatically mean safe: ask a clinician or pharmacist before changing your care.

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At a glance

Traditional uses history, not proof

Studied for research

Iron pills for tested iron deficiency or anemia, high certainty for raising hemoglobin
Iron during pregnancy, moderate certainty
Iron for tiredness when not anemic, low certainty
Iron-rich foods and meal combinations, low certainty
Vitamin C with iron, low certainty (tiny gain)
Tea and coffee timing, low certainty
Alternate-day iron, low certainty
Fortified foods and counselling, low certainty
Lactoferrin, low certainty
Iron cookware, mixed

Main compounds

Iron
Ferritin
Vitamin C
Lactoferrin
Polyphenols (tea and coffee)

Common forms

Iron tablets prescribed after a blood test
Iron-rich foods
Fortified cereals and foods
Vitamin C-rich foods and juice
Cast iron cookware

Research links: 2021 Lancet seminar: iron deficiency · 2016 Cochrane review: daily iron for menstruating women · 2018 review: iron for fatigue when not anemic · 2003 trial: iron for unexplained fatigue in non-anemic women · 2026 ASH guideline: diagnosing iron deficiency · NHS: Iron deficiency anaemia · NHLBI: What is anemia? · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Anemia and iron deficiency (blood conditions)
Common names: Anemia (English); Anaemia (English (UK spelling)); Iron deficiency (English); Iron deficiency anemia (English); Anemia ferropénica (Spanish); Deficiencia de hierro (Spanish)
Family or group: Blood condition. Iron deficiency can exist without anemia (Lancet review); anemia has several types, including iron-deficiency, vitamin B12-deficiency, hemolytic and aplastic.
Look-alikes and adulterants: Name: Vitamin B12 or folate deficiency anemia; Note: Lack of a vitamin rather than iron; the blood test checks for it too (NHS).; Name: Haemochromatosis; Note: The opposite problem, iron build-up. Fatigue is a symptom of both.; Name: Sleep apnea, diabetes, overactive thyroid, ME/CFS; Note: NHS lists these as other causes of long-term tiredness.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Modern guidance	Current guidance from the American Society of Hematology (2026) and the British Society of Gastroenterology (2021) is the history read for this page. Nothing older was read.	p42747316

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
Iron	mineral	Needed to make hemoglobin; found in red meat, beans, nuts, dried fruit and fortified cereals (NHS).	Carries oxygen as part of hemoglobin. ^{26 20}	Human data
Ferritin	storage protein	A blood test of iron stores.	Low ferritin points to iron deficiency; it rises with inflammation. ⁵	Human data
Hepcidin	hormone	The main regulator of iron in the body.	Rises after iron doses and limits further absorption. ^{11 16}	Human data
Vitamin C	vitamin	In oranges, grapefruit, kiwi, strawberries, broccoli and tomatoes (MedlinePlus).	Helps absorb iron from food. ^{3 20}	Human data
Polyphenols	plant compounds	In black tea, coffee, cocoa and herbal teas.	Bind iron and lower its absorption from a meal. ⁸	Human data

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Why iron deficiency causes tiredness		Without iron the body cannot make enough hemoglobin to carry oxygen effectively (MedlinePlus). Trials of iron for tiredness measured fatigue scores, not this step. ^{20 7}	Not established
Hepcidin and iron absorption		A Lancet review says hepcidin upregulation by oral iron limits absorption of high-dose oral iron and of iron during inflammation. A trial in iron-depleted women found daily split dosing raised hepcidin and lowered absorption. ^{11 16}	Human data

Isolated compounds versus whole extracts

Iron pills deliver a measured amount of iron in one form; food also brings enhancers and inhibitors (vitamin C, meat tissue, phytate, polyphenols), so food and pills behave differently. A person's own iron status often matters more than the meal.

10benefits and uses looked at

28studies and sources checked

High certaintybest evidence rating found

5lab markers tracked in trials

1 high certainty1 moderate certainty1 mixed findings7 low certainty

What was looked at

The 10 benefits and uses checked for Anemia and Iron Deficiency: Tiredness and Testing, each with how strong the evidence is. Tap one to open it.

Iron pills when blood tests show iron deficiency or anemiaHigh certainty
Iron for tiredness when you are not anemicLow certainty
Iron during pregnancyModerate certainty
Eating iron-rich foods and meal combinationsLow certainty
Vitamin C taken with ironLow certainty
Tea, coffee and herbal tea around iron-rich mealsLow certainty
Taking iron on alternate days instead of every dayLow certainty
Food-based programs: fortified foods and diet counsellingLow certainty
Cooking in cast iron potsMixed findings
Lactoferrin (a milk protein) instead of iron tabletsLow certainty

Lab markers tracked in the studies

HemoglobinSerum ferritinSelf-rated tirednessFractional iron absorptionGut side effects of iron

What is Anemia and Iron Deficiency: Tiredness and Testing good for?

These are the main natural, food and supplement approaches studied for anemia and iron deficiency and how strong the human evidence is for each. They describe what trials found, not advice to try anything. Established medical care is described in the About tab.

Iron pills when blood tests show iron deficiency or anemiaHigh certaintyRaises hemoglobin and lowers anemia risk in women (high-quality evidence for hemoglobin). Gut side effects are common. Iron for tiredness when you are not anemicLow certaintySmall gains in self-rated tiredness in women with low ferritin; no gain in measured fitness. Iron during pregnancyModerate certaintyMay lower anemia and probably lowers iron-deficiency anemia at term in a large Cochrane review. Eating iron-rich foods and meal combinationsLow certaintyMeals with an enhancer let people absorb more iron; no trial showed food alone fixes anemia. Vitamin C taken with ironLow certaintyAdded only 0.14 g/dL hemoglobin to iron pills, called not clinically meaningful. Tea, coffee and herbal tea around iron-rich mealsLow certaintyTea, coffee and herbal teas cut iron absorption from a meal by roughly half to nine-tenths. Taking iron on alternate days instead of every dayLow certaintyAlternate-day iron was absorbed better and caused fewer gut effects in two small trials in young women. Food-based programs: fortified foods and diet counsellingLow certaintyFortified foods and counselling raised hemoglobin in some groups; trials few and biased. Cooking in cast iron potsMixed findingsA review leaned positive but a later randomised trial found no benefit over tablets. Lactoferrin (a milk protein) instead of iron tabletsLow certaintyAbout as good as iron tablets for hemoglobin in four small pregnancy trials, with fewer gut effects.

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.

Iron pills when blood tests show iron deficiency or anemia

High certainty

When tests show low iron, trials in women found iron pills raise hemoglobin and iron stores and lower the chance of anemia. This is what clinicians use. Pills commonly upset the gut. A test comes first, because the same pills can cause harm if iron is not low.

5 studiesTrials used daily oral iron, with or without folic acid or vitamin C,…

Studies, doses and limits

What the trials found

A Cochrane review of 67 trials (8,506 menstruating women) found women given daily iron were less likely to be anemic (RR 0.39; moderate-quality evidence) and iron deficient (RR 0.62; moderate), and had higher hemoglobin (51 studies, 6,861 women; high-quality evidence). Iron improved exercise performance and appeared to reduce symptomatic fatigue. A 2021 Lancet review calls oral iron first-line in most cases and says its absorption is limited by the body hormone hepcidin. NHS, NHLBI and MedlinePlus describe iron tablets as the usual treatment for iron deficiency anemia, taken for months with follow-up blood tests.

Results

Anemia RR 0.39; iron deficiency RR 0.62; hemoglobin higher by a mean difference of 5.30. Gut effects: loose stools RR 2.13, constipation RR 2.07.

Effect sizes as reported

Anemia 95% CI 0.25 to 0.60; iron deficiency 0.50 to 0.76; hemoglobin 4.14 to 6.45; loose stools 1.10 to 4.11; constipation 1.35 to 3.17.

Why this rating

The Cochrane review graded the hemoglobin result as high-quality evidence. The anemia and iron-deficiency results were moderate, and only 10 of 67 trials were at low risk of bias.

Form and dose studied

Trials used daily oral iron, with or without folic acid or vitamin C, at many amounts. Amounts are given only as what each study used. They are not advice. NHS says iron tablets are usually taken for about 6 months and repeat blood tests are done.

Who was studied

Menstruating women, aged about 12 to 50. Many trials were in lower-income settings.

Limits

Not all trials said how they were run. Results for men, older adults and people with other conditions were not read here. Cognitive results were conflicting.

Why researchers looked

Iron is needed to make hemoglobin, so researchers tested whether replacing it fixes low blood counts and symptoms.

Proposed mechanism Hypothesis

Proposed: iron replaces what the body lacks for making red blood cells. The trials measured blood counts, not this step.

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

Gut upset is common (constipation, loose stools, stomach pain, darker stools). Keep iron out of reach of children: an overdose in a young child can be fatal (NHS). Iron should be taken for tested iron deficiency, not by guesswork.

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Iron for tiredness when you are not anemic

Low certainty

In women with unexplained tiredness who were not anemic but had low or borderline iron stores (ferritin), iron tablets reduced self-rated tiredness a little more than placebo. They did not improve measured physical fitness. Benefit seemed limited to people with low ferritin, which is why a blood test comes first.

4 studiesBoth trials used ferrous sulfate providing 80 mg of elemental iron a …

Studies, doses and limits

What the trials found

A Swiss trial of 144 women (2003) found fatigue fell 29 percent with iron and 13 percent with placebo over 4 weeks; only women with ferritin at or below 50 micrograms per liter improved. A French trial of 198 women with ferritin below 50 (2012) found the fatigue score fell 47.7 percent with iron and 28.8 percent with placebo over 12 weeks, with no effect on quality of life, depression or anxiety. A 2018 review of 18 trials found less self-reported fatigue (4 trials, 714 people) but no change in objective physical capacity (9 trials, 235 people).

Results

Swiss trial: difference 0.95 points on a 10-point fatigue scale. French trial: difference 18.9 percentage points in fatigue score. Review: self-reported fatigue SMD -0.38; maximal oxygen consumption SMD 0.11 (no clear change).

Effect sizes as reported

Swiss 95% CI 0.32 to 1.62; French -34.5 to -3.2; review fatigue -0.52 to -0.23; oxygen consumption -0.15 to 0.37.

Why this rating

Benefits were in self-rated tiredness, not in objective measures. Only 4 trials in the review measured fatigue the same way, and placebo groups also improved by 13 to 29 percent.

Form and dose studied

Both trials used ferrous sulfate providing 80 mg of elemental iron a day, for 4 or 12 weeks. That is what the studies used. It is not advice.

Who was studied

Women aged 18 to 55 with unexplained fatigue, not anemic, mostly with low ferritin, in primary care in Switzerland and France.

Limits

Women only. Short trials. In the French trial participants knew what they took. Ferritin rises with inflammation, so interpreting it needs a clinician.

Why researchers looked

Many people feel tired with normal blood counts, so researchers asked whether low iron stores alone could be the reason.

Proposed mechanism Hypothesis

Proposed: low iron stores may affect energy in tissues before anemia appears. Not tested directly in these trials.

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

Side effects of iron were not detailed in the abstracts. Iron is not advised for people who are not iron deficient (NHLBI), and people with haemochromatosis are usually told to avoid it (NHS).

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Iron during pregnancy

Moderate certainty

Pregnancy raises the need for iron. A large review found daily iron during pregnancy may lower the chance of anemia and probably lowers iron-deficiency anemia at term. Babies were also a little less likely to have low birthweight. A pregnancy clinician decides what is right for each person.

3 studiesDaily oral iron alone or with folic acid. Amounts differed between tr…

Studies, doses and limits

What the trials found

A 2024 Cochrane review of 57 trials (48,971 women) found iron may reduce maternal anemia (RR 0.30; low-certainty evidence) and iron deficiency at term (RR 0.51; low) and probably reduces iron-deficiency anemia at term (RR 0.41; moderate). Babies were probably less likely to have low birthweight (RR 0.84; moderate). Preterm birth probably did not differ. The evidence on adverse effects was very uncertain. NHS names pregnancy as a very common cause of iron deficiency anemia, and NHLBI says untreated anemia in pregnancy raises risks for mother and baby.

Results

Anemia RR 0.30; iron deficiency at term RR 0.51; iron-deficiency anemia at term RR 0.41; low birthweight RR 0.84.

Effect sizes as reported

Anemia 0.20 to 0.47; iron deficiency 0.38 to 0.68; iron-deficiency anemia 0.26 to 0.63; low birthweight 0.72 to 0.99.

Why this rating

The Cochrane authors rated the iron-deficiency anemia and low birthweight results as moderate certainty and the anemia and iron deficiency results as low certainty.

Form and dose studied

Daily oral iron alone or with folic acid. Amounts differed between trials and are not advice. Ask a pregnancy clinician about iron.

Who was studied

Pregnant women in many countries; 19 trials were in places with some malaria risk.

Limits

Trials differed widely. No trial reported clinical malaria. Adverse effects and severe anemia were very uncertain.

Why researchers looked

Pregnancy is a common time for iron deficiency, so many trials tested iron during it.

Proposed mechanism Hypothesis

Proposed: iron supports the greater blood volume and the baby's needs. Trials measured outcomes, not this.

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

Stomach upset is the commonest complaint with iron (NHS). Ask your midwife or doctor before taking iron in pregnancy.

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Eating iron-rich foods and meal combinations

Low certainty

Foods such as red meat, beans, nuts, dried fruit and fortified cereals contribute iron, and plant iron is harder to absorb. Studies of whole diets found meals with an absorption enhancer let people absorb more iron. Whether diet changes alone fix anemia was not shown in the trials read here.

5 studiesFood, not pills: for example meals with vitamin C-rich foods or meat …

Studies, doses and limits

What the trials found

A 2013 review of 19 studies found absorption from diets was higher with an enhancer (SMD 0.53) and higher than from low-bioavailability diets (SMD 0.96); single inhibitors did not clearly reduce absorption in whole diets. Absorption ranged from 0.7 to 22.9 percent between studies and depended on iron status, with diet mattering most when ferritin was low. A 2010 review estimates bioavailability of 14 to 18 percent for mixed diets and 5 to 12 percent for vegetarian diets in people with no iron stores, and notes the person's own iron status mattered more than diet composition. NHS, NHLBI and MedlinePlus list red meat, beans, nuts, dried fruit, fortified cereals, dark-green leafy vegetables and vitamin C-rich foods.

Results

Enhancer SMD 0.53; low-bioavailability comparison SMD 0.96; predicted absorption 2.1 to 23.0 percent at ferritin 6 to 80 micrograms per liter.

Effect sizes as reported

Enhancer 95% CI 0.21 to 0.85; low-bioavailability 0.51 to 1.41.

Why this rating

The evidence is on iron absorbed, a stand-in measure. No trial in these reviews tested whether changing meals alone fixes anemia.

Form and dose studied

Food, not pills: for example meals with vitamin C-rich foods or meat tissue. Food sources differ from supplements. NHS says most people can get the iron they need from a varied, balanced diet.

Who was studied

Mostly healthy adults in United States, European and Mexican studies.

Limits

Absorption was measured, not anemia. Results may not apply to other countries or ages. NHS also lists tea, coffee, dairy and high-phytate foods as things that make absorption harder in large amounts.

Why researchers looked

Diet is where iron comes from, so researchers measured how much iron people absorb from different meals and diets.

Proposed mechanism Lab/human absorption studies

Proposed: vitamin C and meat tissue can raise absorption of plant iron, while phytate (in grains and beans) and polyphenols can lower it. Shown for absorption in single-meal studies, not for anemia outcomes.

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

NHS advises limiting red and processed meat because of a probable link with bowel cancer. Liver is a rich iron source that NHS says to avoid during pregnancy.

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Vitamin C taken with iron

Low certainty

Vitamin C helps the body absorb plant iron from a meal. When researchers added vitamin C to iron pills in people with anemia, hemoglobin rose only a tiny amount more, which the authors called not clinically meaningful.

3 studiesVitamin C from supplements or from food or juice taken with iron pill…

Studies, doses and limits

What the trials found

A 2024 review of 10 randomised trials and 1 cohort study (1,930 people with iron deficiency anemia) found iron plus vitamin C raised hemoglobin by 0.14 g/dL and ferritin by 3.23 micrograms per liter more than iron alone. The authors said this was small and likely not clinically important and did not support routine vitamin C with oral iron. NHS suggests orange juice after a tablet may help absorption.

Results

Hemoglobin mean difference 0.14 g/dL (10 studies); ferritin 3.23 micrograms per liter (9 studies).

Effect sizes as reported

Hemoglobin 95% CI 0.08 to 0.20; ferritin 1.63 to 4.84.

Why this rating

The reviewers called the gain small and probably not meaningful, and the studies pooled different products and amounts.

Form and dose studied

Vitamin C from supplements or from food or juice taken with iron pills; amounts varied and are not advice.

Who was studied

People with iron deficiency anemia in 11 studies.

Limits

One included study was not randomised. Funding was not stated in the abstract.

Why researchers looked

Vitamin C is thought to help iron absorption, so researchers tested whether adding it improves treatment.

Proposed mechanism Hypothesis

Proposed: vitamin C keeps iron in a form the gut absorbs more easily. Shown for food in absorption studies.

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

Haemochromatosis: NHS says people with it are usually told to avoid iron or vitamin C supplements.

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Tea, coffee and herbal tea around iron-rich meals

Low certainty

Black tea, coffee, cocoa and even herbal teas such as peppermint and chamomile cut how much iron the body absorbs from a meal in a lab-style study. NHS lists tea and coffee among drinks to have less of when your iron is low.

2 studiesDrinks with a bread meal in the study; no recommendations about amoun…

Studies, doses and limits

What the trials found

A study in adult volunteers measured iron absorption from a bread meal eaten with different drinks. Drinks with 20 to 50 mg polyphenols per serving cut absorption 50 to 70 percent, and 100 to 400 mg cut it 60 to 90 percent. Black tea cut it 79 to 94 percent, peppermint tea 84 percent, cocoa 71 percent, vervain 59 percent, lime flower 52 percent and chamomile 47 percent. Milk added to tea or coffee changed little. NHS lists tea, coffee and dairy among foods that make absorption harder in large amounts.

Results

Absorption reduced by 47 to 94 percent depending on the drink.

Effect sizes as reported

Not given in the abstract.

Why this rating

The test was single meals in healthy volunteers, not people with anemia, so the effect on iron status over time was not tested.

Form and dose studied

Drinks with a bread meal in the study; no recommendations about amounts or timing are made here.

Who was studied

Healthy adult volunteers (number not in the abstract).

Limits

Single test meals. Real-life effects on anemia or ferritin were not measured.

Why researchers looked

Tea and coffee contain polyphenols that bind iron, so researchers measured absorption with a meal.

Proposed mechanism Human absorption study

Shown in healthy adults: polyphenols bind iron so less is absorbed from that meal.

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

This is a food-and-drink note, not a safety warning. Do not stop prescribed iron or change medicines because of it without asking your clinician.

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Taking iron on alternate days instead of every day

Low certainty

Two small Swiss trials in young women with low iron stores found that taking the same iron on alternate days was absorbed better than on consecutive days, and caused fewer gut side effects at the same total. Ferritin ended up similar in the larger trial.

3 studies100 mg iron capsules daily or on alternate days in the 2023 trial, an…

Studies, doses and limits

What the trials found

In a 2017 study of 40 iron-depleted women (study 1), alternate-day iron was absorbed at 21.8 percent versus 16.3 percent for consecutive days; splitting a daily amount in two did not help (20 women, study 2). In a 2023 randomised, placebo-controlled trial of 150 women with ferritin of 30 micrograms per liter or less, ferritin was similar (43.8 versus 44.8) at equal total iron, but gut side effects were less likely with alternate days (ratio 1.56 for consecutive days) and iron deficiency at 6 months was 11.4 percent versus 3.0 percent.

Results

Fractional absorption 21.8 versus 16.3 percent (P=0.0013); gut side effect ratio 1.56; iron deficiency at 6 months 11.4 versus 3.0 percent (P=0.049).

Effect sizes as reported

Side effects 95% CI 1.38 to 1.77.

Why this rating

Two small trials in young Swiss women with low stores, not diagnosed anemia. The 2017 authors say findings need confirming in iron-deficient anemic patients.

Form and dose studied

100 mg iron capsules daily or on alternate days in the 2023 trial, and 60 mg or 120 mg doses in the 2017 studies. These are the study amounts and not advice.

Who was studied

Young women in Switzerland with low iron stores.

Limits

Small, one country, women only. The 2017 study was open-label.

Why researchers looked

Iron taken daily raises a hormone called hepcidin that can block later absorption, so researchers tested spacing.

Proposed mechanism Human absorption study

Shown: higher hepcidin after consecutive-day dosing was linked to lower fractional absorption in one trial.

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

Gut side effects (constipation, stomach pain, nausea) are the common issue. A clinician should set the schedule.

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Food-based programs: fortified foods and diet counselling

Low certainty

Reviews found fortified foods, iron-rich foods and diet counselling can raise hemoglobin in some groups, but the trials are few and often at risk of bias. Few reviews tested food-only plans in adults.

2 studiesFortified cereals, milk and powders; counselling programs. Details di…

Studies, doses and limits

What the trials found

A 2021 Cochrane overview of 75 reviews found iron fortification of foods raised hemoglobin and reduced anemia in infants, and daily iron supplements helped many groups; only a limited number of reviews tested ways to improve dietary diversity and quality. A 2022 review of 7 trials in pregnant women found fortified products, iron-rich foods or counselling were all reported effective, but most trials were at medium risk of bias and some at high risk.

Results

Not pooled across reviews.

Effect sizes as reported

Not given.

Why this rating

The 2022 review has only 7 trials with bias concerns; the 2021 overview found few reviews on food-based plans.

Form and dose studied

Fortified cereals, milk and powders; counselling programs. Details differed and are not advice.

Who was studied

Infants, children and pregnant women, mostly in programs around the world.

Limits

Food-only trials in adults with iron deficiency anemia were not read.

Why researchers looked

Where iron pills are hard to use, programs tested adding iron to foods or teaching people to eat more of it.

Proposed mechanism Hypothesis

Proposed: adding iron to the food supply raises intake across a group.

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

Fortified foods can add iron on top of what a person already takes; ask a clinician if you already take iron pills.

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Cooking in cast iron pots

Mixed findings

A few trials in lower-income countries tried iron cooking pots. One review found some benefit in people who were anemic, and a later trial in Benin found no benefit over iron tablets. Results depended on how consistently pots were used.

2 studiesCast iron or blue steel pots; the amount of iron added depends on the…

Studies, doses and limits

What the trials found

A 2003 review of 3 trials found some evidence that food cooked in iron pots raised hemoglobin in anemic or iron-deficient people, with effects affected by compliance, age, malaria and hookworm. A 2008 randomised trial in Benin (339 people) found no difference in hemoglobin after 6 months, and ferritin was higher in the group taking iron supplements; the authors found no evidence that iron pots work against iron-deficiency anemia.

Results

Review: some effect in anemic people. Benin trial: no hemoglobin difference at 6 months.

Effect sizes as reported

Not given in the abstracts.

Why this rating

The review leaned slightly positive, the later randomised trial did not, and both are about lower-income settings.

Form and dose studied

Cast iron or blue steel pots; the amount of iron added depends on the food and time.

Who was studied

Children, girls and women in developing-country settings.

Limits

Only a few trials; compliance varied; results may not apply to other settings.

Why researchers looked

Iron leaches from cast iron into food, so researchers tested whether cooking in iron pots raises hemoglobin.

Proposed mechanism Hypothesis

Proposed: iron leaching from the pot adds absorbable iron. A later trial questioned whether it is absorbed.

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

No specific harm was reported in the abstracts. People with haemochromatosis should ask a clinician about extra iron sources.

^{6 13}

Lactoferrin (a milk protein) instead of iron tablets

Low certainty

In four small trials of pregnant women with iron-deficiency anemia, lactoferrin raised hemoglobin about as well as iron tablets, with fewer gut side effects. The set of trials is small, and a clinician should guide anemia treatment.

2 studiesDaily oral bovine lactoferrin compared with daily ferrous iron; amoun…

Studies, doses and limits

What the trials found

A 2018 meta-analysis of 4 randomised trials (600 pregnant women) found hemoglobin after 4 weeks was slightly higher with bovine lactoferrin than with iron sulfate (MD 0.77). In mild anemia there was no significant difference; in moderate anemia (one trial, 228 women) lactoferrin was better. Gut side effects were significantly lower with lactoferrin. The 2021 Cochrane overview also reports oral bovine lactoferrin beat ferrous iron for hemoglobin and gut effects in one review of pregnant women.

Results

Hemoglobin MD 0.77 at 4 weeks (P=0.04); fewer gut side effects.

Effect sizes as reported

Hemoglobin 95% CI 0.04 to 1.55.

Why this rating

Only 4 trials and 600 people, and the gain was small; results may differ outside pregnancy.

Form and dose studied

Daily oral bovine lactoferrin compared with daily ferrous iron; amounts differ and are not advice.

Who was studied

Pregnant women with iron-deficiency anemia.

Limits

The authors' conclusion that lactoferrin should be the first choice goes further than four trials can show.

Why researchers looked

Iron pills upset many stomachs, so researchers tested a milk protein that binds iron.

Proposed mechanism Hypothesis

Proposed: lactoferrin carries iron and may be gentler on the gut. Not shown in these trials.

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

Lactoferrin is a milk protein, so people with milk allergy should ask a clinician. Not studied here in children or men.

^{1 19}

Connections to the rest of health

How Anemia and Iron Deficiency: Tiredness and Testing 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	Evidence status	Context	Studies
Reduce Fatigue	High certainty	Iron pills when blood tests show iron deficiency or anemia: When tests show low iron, trials in women found iron pills raise hemoglobin and iron stores and lower the chance of anemia. This is what clinicians use. Pills commonly upset the gut. A test comes first, because the same pills can cause harm if iron is not low. Iron for tiredness when you are not anemic: In women with unexplained tiredness who were not anemic but had low or borderline iron stores (ferritin), iron tablets reduced self-rated tiredness a little more than placebo. They did not improve measured physical fitness. Benefit seemed limited to people with low ferritin, which is why a blood test comes first.	^{10 11 25 21 20 18 17 7 27 4 14 3 24 16 28 19 6 13 1}
Reduce Fatigue	Low certainty	Eating iron-rich foods and meal combinations: Foods such as red meat, beans, nuts, dried fruit and fortified cereals contribute iron, and plant iron is harder to absorb. Studies of whole diets found meals with an absorption enhancer let people absorb more iron. Whether diet changes alone fix anemia was not shown in the trials read here.	^{2 9 26 25 21}
Reduce Fatigue	Low certainty	Tea, coffee and herbal tea around iron-rich meals: Black tea, coffee, cocoa and even herbal teas such as peppermint and chamomile cut how much iron the body absorbs from a meal in a lab-style study. NHS lists tea and coffee among drinks to have less of when your iron is low.	^{8 25}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Blood	Biological association	High certainty	Studied for: Iron pills when blood tests show iron deficiency or anemia Studied for: Iron for tiredness when you are not anemic	^{10 11 25 21 20 18 17 7 27 4 14 2 9 26 3 24 8 16 28 19 6 13 1}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Haemochromatosis		Health agency guidance	People with this inherited iron build-up are usually advised to avoid iron or vitamin C supplements. Preparation or compound: Iron and vitamin C supplements	²⁴
Fatigue: when to get help		Health agency guidance	Other causes of tiredness that a clinician checks for. Preparation or compound: Evaluation	²⁷

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Hemoglobin	Biological association	High certainty	Measured in trials: Higher is better when it starts low. A lab change is not the same as a health benefit.	^{10 7}
Serum ferritin	Biological association	Low certainty	Measured in trials: Higher after treatment shows stores refilling. A lab change is not the same as a health benefit.	^{17 5}
Self-rated tiredness	Biological association	Low certainty	Measured in trials: Lower is better. A lab change is not the same as a health benefit.	^{18 17 7}
Fractional iron absorption	Biological association	Low certainty	Measured in trials: Higher means more iron absorbed. A lab change is not the same as a health benefit.	^{16 8}
Gut side effects of iron	Biological association	Low certainty	Measured in trials: Fewer is better. A lab change is not the same as a health benefit.	^{28 1}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Iron	Biological association	Human	Carries oxygen as part of hemoglobin.	^{26 20}
Ferritin	Biological association	Human	Low ferritin points to iron deficiency; it rises with inflammation.	⁵
Hepcidin	Biological association	Human	Rises after iron doses and limits further absorption.	^{11 16}
Vitamin C	Biological association	Human	Helps absorb iron from food.	^{3 20}
Polyphenols	Biological association	Human	Bind iron and lower its absorption from a meal.	⁸

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 31, 2026).

Evidence at a glance: what the research found for 10 outcomes

1High certainty

1Moderate certainty

7Low certainty

1Mixed findings

Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.

Iron pills when blood tests show iron deficiency or anemia 5 studies High certainty Iron for tiredness when you are not anemic 4 studies Low certainty Iron during pregnancy 3 studies Moderate certainty Eating iron-rich foods and meal combinations 5 studies Low certainty Vitamin C taken with iron 3 studies Low certainty Tea, coffee and herbal tea around iron-rich meals 2 studies Low certainty Taking iron on alternate days instead of every day 3 studies Low certainty Food-based programs: fortified foods and diet counselling 2 studies Low certainty Cooking in cast iron pots 2 studies Mixed findings Lactoferrin (a milk protein) instead of iron tablets 2 studies Low certainty

The evidence

The research centre for Anemia and Iron Deficiency: Tiredness and Testing. 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 searched PubMed, re-read the abstract of every review and trial cited, and read the NHS, NHLBI and MedlinePlus pages directly. Full texts were not read. Certainty ratings are the compiler's own reading, except where a review gives its own grade (stated in the text). Funding is not stated in most abstracts, and this is noted where relevant.

Study library: every study we checked 28

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Abu Hashim 2018 Lactoferrin or ferrous salts for iron deficiency anemia in pregnancy: A meta-analysis of randomized trials Eur J Obstet Gynecol Reprod Biol · PMID 29059584 · DOI	Systematic review meta analysis	600 Pregnant women with iron-deficiency anemia; 4 randomised trials	Daily oral bovine lactoferrin (a milk protein) About 4 weeks (primary outcome) · vs Daily oral ferrous iron	Hemoglobin rose slightly more with lactoferrin (0.77); in mild anemia there was no significant difference, and in moderate anemia (one trial) lactoferrin did better. Gut side effects were significantly lower with lactoferrin. Hemoglobin mean difference 0.77 (P=0.04) (95% CI 0.04 to 1.55) Methods, limits and funding Outcomes: Change in hemoglobin at 4 weeks; ferritin; gut side effects Limitations: Four small trials; the authors' conclusion that lactoferrin should be the agent of choice goes beyond what four trials can show. Funding and conflicts: No funding statement in the abstract. Read: abstract
Collings 2013 The absorption of iron from whole diets: a systematic review Am J Clin Nutr · PMID 23719560 · DOI	Systematic review meta analysis	19 studies from the United States, Europe and Mexico measuring iron absorption from whole diets; a regression used 58 US individuals	Whole diets with or without enhancers and inhibitors of iron absorption Varied · vs Low-bioavailability diets or diets without an enhancer	Absorption was higher with an enhancer (SMD 0.53) and higher than with low-bioavailability diets (SMD 0.96); single inhibitors did not clearly reduce it. Absorption varied from 0.7 to 22.9 percent between studies and depended on iron status, with diet mattering more at low ferritin. Enhancer SMD 0.53; low-bioavailability comparison SMD 0.96; predicted absorption 2.1 to 23.0 percent at ferritin 6 to 80 micrograms per liter (Enhancer 0.21 to 0.85; low-bioavailability 0.51 to 1.41) Methods, limits and funding Outcomes: Percent non-heme iron absorbed Limitations: Absorption was measured, not anemia outcomes; findings may not apply to developing countries or other age groups. Funding and conflicts: No funding statement in the abstract. Read: abstract
Deng 2024 Efficacy of vitamin C with Fe supplementation in patients with iron deficiency anemia: a systematic review and meta-analysis Blood Vessel Thromb Hemost · PMID 40765927 · DOI	Systematic review meta analysis	1930 People with iron deficiency anemia; 10 randomised trials (1,782) and 1 cohort study (148)	Oral iron with vitamin C compared with oral iron alone Varied · vs Iron alone	Adding vitamin C raised hemoglobin by 0.14 g/dL and ferritin by 3.23 micrograms per liter. The authors called this small and likely clinically insignificant and did not support routine vitamin C with oral iron. Hemoglobin MD 0.14 g/dL (10 studies); ferritin MD 3.23 micrograms per liter (9 studies) (Hemoglobin 0.08 to 0.20; ferritin 1.63 to 4.84) Methods, limits and funding Outcomes: Change in hemoglobin; ferritin; adverse events Limitations: Pools different iron products and vitamin C amounts; one included study was not randomised. Funding and conflicts: No funding statement in the abstract. Read: abstract
Finkelstein 2024 Daily oral iron supplementation during pregnancy Cochrane Database Syst Rev · PMID 39145520 · DOI	Systematic review meta analysis	48971 Pregnant women; 57 trials, 48,971 women; 19 trials in malaria-endemic settings	Daily oral iron alone, or with folic acid or other vitamins and minerals Varied · vs Placebo or no iron	Iron may reduce maternal anemia (RR 0.30, low certainty) and iron deficiency at term (RR 0.51, low certainty) and probably reduces iron-deficiency anemia at term (RR 0.41, moderate certainty). Babies were probably less likely to be low birthweight (RR 0.84, moderate). Evidence on adverse effects is very uncertain. Anemia RR 0.30; iron deficiency at term RR 0.51; iron-deficiency anemia at term RR 0.41; low birthweight RR 0.84 (Anemia 0.20 to 0.47; iron deficiency 0.38 to 0.68; iron-deficiency anemia 0.26 to 0.63; low birthweight 0.72 to 0.99) Methods, limits and funding Outcomes: Maternal anemia, iron deficiency, iron-deficiency anemia at term; infant birthweight and other outcomes; adverse effects Limitations: Wide differences between trials; adverse-effect and severe-anemia data very uncertain; no trials reported clinical malaria. Funding and conflicts: Review supported by the World Health Organization (agency listed in the record). Read: abstract
Garcia-Casal 2021 Serum or plasma ferritin concentration as an index of iron deficiency and overload Cochrane Database Syst Rev · PMID 34028001 · DOI	Systematic review diagnostic	108 studies; 72 studies (6,059 people) on iron deficiency, 36 studies (1,927 people) on iron overload	Ferritin blood test compared with bone marrow or liver iron Not a trial · vs Not given	At a threshold of 30 micrograms per liter there was low-certainty evidence that ferritin is reasonably sensitive (79 percent) and very specific (98 percent) for iron deficiency in people seeking medical care. Evidence for iron overload was very low certainty, and it is unclear how well ferritin screens people with no symptoms. Sensitivity 79 percent, specificity 98 percent at 30 micrograms per liter (9 studies, 512 people) (Sensitivity 58 to 91 percent; specificity 91 to 100 percent) Methods, limits and funding Outcomes: Sensitivity and specificity of ferritin Limitations: Thresholds varied from 12 to 200 micrograms per liter across studies; ferritin rises with inflammation. Funding and conflicts: Review supported by the World Health Organization (agency listed in the record). Read: abstract
Geerligs 2003 Food prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries: a systematic review J Hum Nutr Diet · PMID 12859709 · DOI	Systematic review	Participants aged 4 months or older in 3 eligible randomised trials in developing countries	Food cooked in cast iron pots Varied · vs Food cooked in non-iron pots	There was some evidence that eating food from iron pots raised hemoglobin in anemic or iron-deficient people. The effect seemed to depend on how consistently pots were used, age, malaria and hookworm. Not pooled in the abstract (Not given) Methods, limits and funding Outcomes: Hemoglobin; compliance with pot use Limitations: Only 3 trials; searches ended in 2002; compliance varied. Funding and conflicts: No funding statement in the abstract. Read: abstract
Houston 2018 Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials BMJ Open · PMID 29626044 · DOI	Systematic review meta analysis	1170 Adults aged 18 or older who were iron deficient but not anemic; 18 trials plus 2 companion papers (searched to October 2016)	Oral, intramuscular or intravenous iron, any amount or duration Varied · vs Placebo or active therapy	Iron was linked to less self-reported fatigue (4 trials, 714 people) but not to better objective physical capacity such as maximal oxygen consumption (9 trials, 235 people). Hemoglobin and ferritin rose. Fatigue SMD -0.38; maximal oxygen consumption SMD 0.11; hemoglobin MD 4.01 g/L; ferritin MD 9.23 (units as printed in the abstract) (Fatigue 95% CI -0.52 to -0.23; oxygen consumption -0.15 to 0.37; hemoglobin 1.22 to 6.81; ferritin 6.48 to 11.97) Methods, limits and funding Outcomes: Self-reported fatigue; objective physical capacity; hemoglobin; ferritin Limitations: Only 4 trials measured fatigue the same way; fatigue is self-reported; includes more than one iron route. Funding and conflicts: No funding statement in the abstract. Registration: PROSPERO CRD42014007085 Read: abstract
Hurrell 1999 Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages Br J Nutr · PMID 10999016	Controlled human absorption study	Adult volunteers (number not given in the abstract) eating a bread meal with different drinks, measured by radio-iron in red cells	Black tea, coffee, cocoa and herb teas (chamomile, vervain, lime flower, pennyroyal, peppermint) with a bread meal Single meals · vs Water	All the drinks cut iron absorption in a dose-dependent way: 50 to 70 percent with 20 to 50 mg polyphenols per serving and 60 to 90 percent with 100 to 400 mg. Black tea cut it 79 to 94 percent, peppermint tea 84 percent, cocoa 71 percent, camomile 47 percent. Adding milk changed little. Absorption reductions: black tea 79-94 percent; peppermint 84 percent; cocoa 71 percent; chamomile 47 percent (Not given in the abstract) Methods, limits and funding Outcomes: Iron absorption from the bread meal Limitations: Single test meals in healthy adults; it did not test anemia or long-term iron status. Funding and conflicts: No funding statement in the abstract. Read: abstract
Hurrell 2010 Iron bioavailability and dietary reference values Am J Clin Nutr · PMID 20200263 · DOI	Narrative review	Review of iron absorption from mixed and vegetarian diets	Not an intervention study: phytate, polyphenols, calcium, ascorbic acid and muscle tissue as dietary factors Not given · vs Not given	Estimated iron bioavailability is 14 to 18 percent for mixed diets and 5 to 12 percent for vegetarian diets in people with no iron stores. Single-meal studies repeatedly show effects of phytate, polyphenols, calcium, ascorbic acid and muscle tissue; in multi-meal studies with a varied diet the effect of single components was more modest. The person's own iron status generally had a greater effect than diet composition. Bioavailability 14-18 percent (mixed diet), 5-12 percent (vegetarian) in people with no iron stores (Not given in the abstract) Methods, limits and funding Outcomes: Estimated bioavailability; effect of dietary factors on absorption Limitations: Narrative review; the abstract does not describe how studies were chosen. Funding and conflicts: No funding statement in the abstract. Read: abstract
Low 2016 Daily iron supplementation for improving anaemia, iron status and health in menstruating women Cochrane Database Syst Rev · PMID 27087396 · DOI	Systematic review meta analysis	8506 Menstruating women (or women aged 12 to 50); 67 trials, 8,506 women; only 10 trials at low overall risk of bias	Daily oral iron (at least 5 days a week), with or without folic acid or vitamin C Varied · vs Control or placebo	Women taking iron were less likely to be anemic (RR 0.39) and iron deficient (RR 0.62) and had higher hemoglobin. Exercise performance improved and symptomatic fatigue appeared to fall. Loose stools, constipation and other gut symptoms were more common with iron. Anemia RR 0.39; hemoglobin mean difference 5.30 (51 studies, 6,861 women); iron deficiency RR 0.62; loose stools RR 2.13; constipation RR 2.07 (Anemia 0.25 to 0.60; hemoglobin 4.14 to 6.45; iron deficiency 0.50 to 0.76; loose stools 1.10 to 4.11; constipation 1.35 to 3.17) Methods, limits and funding Outcomes: Anemia, hemoglobin, iron deficiency, side effects, exercise performance, fatigue Limitations: Many trials gave too little detail to judge quality; cognitive results were conflicting; only one study reported iron-deficiency anemia specifically. Funding and conflicts: Cochrane review; no funding conflict stated in the abstract. Read: abstract
Pasricha 2021 Iron deficiency Lancet · PMID 33285139 · DOI	Narrative review	Seminar review of iron deficiency worldwide	Overview of causes, diagnosis and treatment Not a trial · vs Not given	Iron deficiency is among the leading contributors to the global burden of disease and affects children and premenopausal women most. Problems can occur without anemia. Oral iron is first-line in most cases, and its absorption is limited by hepcidin. An underlying cause should be sought; coeliac disease screening should be considered, and endoscopy is warranted in men and postmenopausal women with iron-deficiency anemia. Not a trial (Not given) Methods, limits and funding Outcomes: Causes, diagnosis, treatment Limitations: Narrative seminar; no pooled data in the abstract. Funding and conflicts: No funding statement in the abstract. Read: abstract
Powers 2026 American Society of Hematology 2026 guidelines for diagnosis of iron deficiency Blood Adv · PMID 42747316 · DOI	Clinical practice guideline	People of all ages worldwide being evaluated for iron deficiency	Serum ferritin thresholds and other diagnostic criteria Not a trial · vs Not given	The panel made 5 recommendations, including serum ferritin thresholds for specific populations, with the aim of diagnosing iron deficiency whether or not anemia is present, and guidance for people with inflammation. The abstract does not list the thresholds. Five recommendations; thresholds not in the abstract (Not given) Methods, limits and funding Outcomes: Diagnosis of iron deficiency, with or without anemia Limitations: Only the abstract was read, so the threshold numbers are not given on this page. Funding and conflicts: The panel was balanced to limit conflicts of interest (abstract); the University of Kansas Health System supported the process. Read: abstract
Sharieff 2008 Is cooking food in iron pots an appropriate solution for the control of anaemia in developing countries? A randomised clinical trial in Benin Public Health Nutr · PMID 17935647 · DOI	Randomised controlled trial	339 161 households in Benin: children 6 to 24 months, girls 11 to 15 years and women 15 to 44 years; about half were anemic at the start	Cast iron pots or blue steel pots for cooking 6 months · vs Oral iron (Sprinkles for children, iron tablets for girls and women)	Hemoglobin did not differ between groups at 6 months, and ferritin was higher in the control group on iron supplements. The authors found no evidence that iron cooking pots are effective against iron-deficiency anemia. Ferritin difference between groups P<0.0001 (Not given in the abstract) Methods, limits and funding Outcomes: Hemoglobin, serum ferritin, C-reactive protein Limitations: Households not individuals were randomised; the control group received supplements, not nothing. Funding and conflicts: No funding statement in the abstract. Read: abstract
Skolmowska 2022 Effectiveness of Dietary Interventions in Prevention and Treatment of Iron-Deficiency Anemia in Pregnant Women: A Systematic Review of Randomized Controlled Trials Nutrients · PMID 35893877 · DOI	Systematic review	Pregnant women (anemic or mixed groups); 7 randomised trials	Fortified products, regular iron-rich foods or dietary counselling Weeks to six months or longer · vs Placebo, supplementation or control	All the dietary approaches were reported as effective at improving hemoglobin, but most trials were at medium risk of bias and some at high risk, so more rigorous trials are needed. Not pooled (Not given) Methods, limits and funding Outcomes: Hemoglobin Limitations: Only 7 trials, mixed designs, bias concerns. Funding and conflicts: No funding statement in the abstract. Registration: PROSPERO CRD42021261235 Read: abstract
Snook 2021 British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults Gut · PMID 34497146 · DOI	Clinical practice guideline	Adults with iron deficiency anemia	Blood testing, iron replacement and investigation for the cause Not a trial · vs Not given	Iron deficiency anemia can generally be diagnosed by blood tests. About a third of men and postmenopausal women with it have an underlying abnormality, most often in the gut. Good management combines iron replacement with investigation to find the cause. Unexplained iron deficiency anemia in at-risk people is an accepted reason for fast-track referral in the UK because gut cancers can present this way, often without specific symptoms. About one third of men and postmenopausal women with a gut abnormality (Not given) Methods, limits and funding Outcomes: Diagnosis and cause-finding in iron deficiency anemia Limitations: UK guideline from a gastroenterology society; the abstract is a summary. Funding and conflicts: No funding statement in the abstract. Read: abstract
Stoffel 2017 Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials Lancet Haematol · PMID 29032957 · DOI	Randomised controlled trial	60 Iron-depleted women aged 18 to 40 (ferritin 25 micrograms per liter or less) in Switzerland: 40 in study 1, 20 in study 2	Labelled ferrous sulfate (60 mg iron on consecutive or alternate days; 120 mg once or split into two 60 mg doses) as used in the studies 14 to 28 days (study 1); 3 days (study 2) · vs Other schedule (within-person comparison)	Iron taken on alternate days was absorbed better than on consecutive days (about 21.8 versus 16.3 percent). Splitting the daily amount into two did not raise absorption and raised hepcidin. No serious adverse events. Fractional absorption 21.8 versus 16.3 percent (P=0.0013) (Geometric means with SD ranges only in the abstract) Methods, limits and funding Outcomes: Iron absorption and serum hepcidin Limitations: Open-label, small, women with low stores but not necessarily anemic; authors say findings need confirming in iron-deficient anemic patients. Funding and conflicts: Swiss National Science Foundation. Registration: NCT02175888 and NCT02177851 Read: abstract
Vaucher 2012 Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial CMAJ · PMID 22777991 · DOI	Randomised controlled trial	198 Women aged 18 to 53 with fatigue, hemoglobin above 12.0 g/dL and ferritin below 50 micrograms per liter, from 44 primary care practices in France	Oral ferrous sulfate, 80 mg a day of elemental iron (the amount used in the study, not advice) 12 weeks · vs Placebo	The fatigue score fell 47.7 percent with iron and 28.8 percent with placebo. There was no significant effect on quality of life, depression or anxiety. Hemoglobin rose 0.32 g/dL and ferritin 11.4 micrograms per liter more than placebo. Difference -18.9 percent in fatigue score (P=0.02) (95% CI -34.5 to -3.2) Methods, limits and funding Outcomes: Fatigue score (Current and Past Psychological Scale); quality of life, depression, anxiety; hemoglobin, ferritin Limitations: Closed-label, observer-blinded design (people knew which they took); women only. Funding and conflicts: No funding statement in the abstract. Read: abstract
Verdon 2003 Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial BMJ · PMID 12763985 · DOI	Randomised controlled trial	144 Women aged 18 to 55 with unexplained fatigue and no anemia, in western Switzerland (primary care); 136 (94 percent) finished	Oral ferrous sulphate, 80 mg a day of elemental iron (the amount used in the study, not advice) 4 weeks · vs Placebo	Fatigue fell by 1.82 of 6.37 points (29 percent) with iron and by 0.85 of 6.46 points (13 percent) with placebo (difference 0.95 points). Only women with ferritin at or below 50 micrograms per liter improved. Difference 0.95 points (P=0.004) (95% CI 0.32 to 1.62) Methods, limits and funding Outcomes: Fatigue on a 10-point visual analogue scale Limitations: Four weeks only; women only; the benefit was limited to those with low or borderline ferritin. Funding and conflicts: No funding statement in the abstract. Read: abstract
da Silva Lopes 2021 Nutrition-specific interventions for preventing and controlling anaemia throughout the life cycle: an overview of systematic reviews Cochrane Database Syst Rev · PMID 34564844 · DOI	Overview of reviews	75 systematic reviews across the life cycle (infants to pregnant women); 33 gave GRADE ratings	Iron pills or drops, fortified foods, micronutrient powders and dietary diversity or counselling Varied · vs No treatment, placebo or other	Daily iron supplements may raise hemoglobin and reduce anemia and iron-deficiency anemia in several groups. Iron fortification of foods in infants and iron pots with children may help in places with low malaria risk. Only a limited number of reviews tested ways to improve dietary diversity and quality. Not pooled across reviews (Not given) Methods, limits and funding Outcomes: Hemoglobin, anemia, iron-deficiency anemia, iron deficiency, adverse effects Limitations: An overview of reviews; ratings varied from high to very low; few reviews on dietary diversity. Funding and conflicts: Review supported by the World Health Organization (agency listed in the record). Read: abstract
s-medlineplus MedlinePlus Medical Encyclopedia: Iron deficiency anemia (review date 1 April 2025) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhlbi-ida NHLBI, NIH: Iron-deficiency anemia (last updated 24 March 2022) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhlbi-tx NHLBI, NIH: Anemia - Treatment and management (last updated 24 March 2022) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhlbi-what NHLBI, NIH: Anemia - What is anemia? (last updated 24 March 2022) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhs-haem NHS: Haemochromatosis (overview page) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhs-ida NHS: Iron deficiency anaemia (page last reviewed 26 January 2024) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhs-iron NHS: Vitamins and minerals - Iron (page last reviewed 3 August 2020) · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhs-tired NHS: Tiredness and fatigue (page last reviewed 2 June 2023) · Source	Health agency n/a			Methods, limits and funding Read: full-text
von Siebenthal 2023 Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study EClinicalMedicine · PMID 38021373 · DOI	Randomised controlled trial	150 Young Swiss women with ferritin 30 micrograms per liter or less, 75 per group	100 mg iron capsules daily for 90 days then placebo, or the same capsule on alternate days for 180 days (equal total amount; as used in the trial) 180 days · vs Alternate-day versus consecutive-day schedule with placebo capsules	At equal total iron, ferritin was the same (43.8 versus 44.8 micrograms per liter). Gut side effects on iron days were more likely with consecutive-day dosing (ratio 1.56). Iron deficiency at 6 months was 11.4 percent versus 3.0 percent, favoring alternate days. Side effects LPR 1.56 (P<0.0001); iron deficiency at 6 months 11.4 versus 3.0 percent (P=0.049) (Side effects 95% CI 1.38 to 1.77) Methods, limits and funding Outcomes: Serum ferritin; gastrointestinal side effects; iron deficiency; hepcidin Limitations: Young Swiss women with low stores, not diagnosed anemia; one country. Funding and conflicts: Swiss National Science Foundation. Registration: NCT05105438 Read: abstract

What we do not know yet

No randomised trial of any herb, seaweed or 'blood-building' product for anemia was read.
Food-only plans for diagnosed iron deficiency anemia in adults were not read.
Iron-for-tiredness trials were short and mostly in women; results for men and older adults were not read.
The detailed ferritin thresholds in the 2026 guideline were not read (abstract only).
The NIH Office of Dietary Supplements iron page was blocked, so its official upper limit is not quoted.
Full texts were not read.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

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".

Organ function 1

●

Hemoglobin

Higher is better when it starts low in trials

The iron-rich protein in red blood cells that carries oxygen, measured in a blood test.

High certainty

Results and what it means

Why it was measured

It is the main number used to say whether someone is anemic.

Statistical vs. clinical meaning

A large and reliable rise in the Cochrane review, but only part of how someone feels.

Study	Result	People	Product
¹⁰	Higher by a mean difference of 5.30 (95% CI 4.14 to 6.45).	8,506 menstruating women in 67 trials	Daily oral iron
⁷	Higher by 4.01 g/L (95% CI 1.22 to 6.81) in iron-deficient non-anemic adults.	1,170 adults in 18 trials	Iron by any route

^{10 7}

Other 4

●

Serum ferritin

Higher after treatment shows stores refilling in trials

A blood test of the protein that stores iron; low ferritin points to low iron stores.

Low certainty

Results and what it means

Why it was measured

It shows iron stores before anemia appears and guides who might benefit from iron.

Statistical vs. clinical meaning

Ferritin is a useful marker but rises with inflammation, and thresholds vary between guidelines.

Study	Result	People	Product
¹⁷	Ferritin rose 11.4 micrograms per liter more than placebo at 12 weeks.	198 women with ferritin below 50	Oral iron
⁵	At a cutoff of 30 micrograms per liter ferritin had 79 percent sensitivity and 98 percent specificity for iron deficiency in people seeking care.	9 studies, 512 adults	Diagnostic test review

^{17 5}

●

Self-rated tiredness

Lower is better in trials

A score from a questionnaire or a 0 to 10 scale on which people rate how tired they feel.

Low certainty

Results and what it means

Why it was measured

Tiredness is the main complaint that sends people to the doctor.

Statistical vs. clinical meaning

Subjective and affected by placebo; objective fitness did not improve in the review.

Study	Result	People	Product
¹⁸	Fell 29 percent with iron versus 13 percent with placebo at 4 weeks.	144 non-anemic women	Iron for 4 weeks
⁷	Standardised mean difference -0.38 (95% CI -0.52 to -0.23) for iron.	714 people in 4 trials	Iron

^{18 17 7}

●

Fractional iron absorption

Higher means more iron absorbed in trials

The share of an iron dose that the gut absorbs, measured with labelled iron.

Low certainty

Results and what it means

Why it was measured

It shows how well different schedules, foods and drinks let iron in.

Statistical vs. clinical meaning

A stand-in measure from small studies, not an anemia outcome.

Study	Result	People	Product
¹⁶	About 21.8 percent on alternate days versus 16.3 percent on consecutive days.	40 iron-depleted women	Labelled iron sulfate
⁸	Black tea cut absorption by 79 to 94 percent and peppermint tea by 84 percent compared with water.	Adult volunteers	A bread meal with different drinks

^{16 8}

●

Gut side effects of iron

Fewer is better in trials

Constipation, loose stools, stomach pain and nausea reported by people taking iron.

Low certainty

Results and what it means

Why it was measured

They are the main reason people stop iron, so schedules and alternatives were compared.

Statistical vs. clinical meaning

Based on small trials in specific groups.

Study	Result	People	Product
²⁸	Consecutive-day dosing had 1.56 times the chance of gut side effects on iron days compared with alternate days.	150 young women	Iron on consecutive or alternate days
¹	Significantly fewer gut side effects with lactoferrin than with iron sulfate.	600 pregnant women in 4 trials	Bovine lactoferrin versus ferrous iron

^{28 1}

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 5

Test first: tiredness alone cannot show low iron. Tiredness has many causes, including poor sleep, sleep apnea, diabetes, an overactive thyroid and long-term fatigue conditions. A blood test is how anemia and iron deficiency are checked. NHLBI says iron supplements are generally not given to people who do not have iron-deficiency anemia, because too much iron can damage organs. Health agency guidance ^{27 22 25}
Anemia can be a sign of something else. NHLBI says anemia may be a sign of a more serious condition, such as bleeding in the stomach, kidney disease, cancer or an autoimmune disease. A British gastroenterology guideline says about a third of men and postmenopausal women with iron deficiency anemia have an underlying abnormality, most often in the gut. Treating the numbers alone can miss the cause. Health agency guidance and guideline ^{23 15}
Too much iron can harm. Haemochromatosis is an inherited condition in which iron slowly builds up and can damage the liver, joints, pancreas and heart. The NHS says people with it are usually advised to avoid iron or vitamin C supplements, and fatigue is one of its symptoms. NHS also lists stomach upset from high iron doses. Health agency guidance ^{24 26}
Keep iron pills away from children. NHS says an overdose of iron in a young child can be fatal, so keep iron supplement tablets out of reach. Health agency guidance ^{25 26}
This page does not replace care. Iron pills, vitamin C, lactoferrin and food changes are things to discuss with a clinician after testing. They are not a way to test or treat yourself. Editorial ^{22 25}

Side effects 4

Effect	How often	Severity and recovery	Evidence
Constipation, loose stools, stomach pain, heartburn, nausea The Cochrane review found more gut symptoms with iron. NHS says to keep taking the tablets, and that taking them with or after food may reduce side effects.	Constipation RR 2.07 and loose stools RR 2.13 in a review of women	Mild to moderate Not stated	Systematic review of randomised trials and health agency guidance ^{10 25 26}
Darker stools NHS lists darker than usual poo as an iron side effect. Black, tar-like stools can also be a sign of bleeding (MedlinePlus), so mention them to a clinician.	Listed by NHS; no rate given	Not graded Not stated	Health agency guidance ²⁵
Iron overdose in a young child NHS: very high doses of iron can be fatal, particularly in children.	Rare	Can be fatal Not stated	Health agency guidance ^{25 26}
Iron build-up in people with haemochromatosis People with this inherited condition are usually told to avoid iron or vitamin C supplements.	Depends on the condition	Can damage liver, joints, pancreas and heart Not stated	Health agency guidance ²⁴

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Tea, coffee, cocoa and herbal teas (peppermint, chamomile and others) with meals food and drink	Polyphenols bind iron in the gut	Cut absorption of iron from a test meal by about 47 to 94 percent depending on the drink	Human absorption study Low certainty ^{8 25}	Not studied for anemia outcomes. NHS lists tea and coffee among drinks to have less of; ask a clinician or dietitian about timing.
Milk, dairy and foods high in phytic acid (wholegrain cereals) food	Can make it harder to absorb iron from other foods and tablets	NHS says large amounts make absorption harder	Health agency guidance Not enough evidence ²⁵	Ask a clinician or dietitian before changing the diet of someone with anemia.
Vitamin C (food or supplement) supplement	Helps absorption of iron	Added only 0.14 g/dL hemoglobin in a review of people with anemia	Systematic review of randomised trials Low certainty ^{3 24}	People with haemochromatosis are usually told to avoid vitamin C supplements (NHS).
Aspirin, ibuprofen and other anti-inflammatory pain medicines prescription and over-the-counter	They can cause stomach bleeding, a common cause of iron loss	NHS and MedlinePlus list regular use as a cause of iron deficiency anemia	Health agency guidance Not enough evidence ^{25 20}	If you take them often and feel tired or pale, tell a clinician. Do not stop prescribed medicines on your own.
Antacids (and the antibiotic tetracycline) taken in large amounts over-the-counter and prescription	Can reduce the iron the body absorbs	MedlinePlus lists them as reasons the body may not absorb enough iron	Health agency guidance Not enough evidence ²⁰	Ask a pharmacist about timing if you take both.
Other supplements or medicines taken together with iron general	Not studied in the sources read	Unknown	Absence of evidence Not enough evidence ²⁶	No interaction study was read for iron with other supplements. Ask a pharmacist before combining.

Who should check first 5

Situation	Advice	Evidence
Haemochromatosis (inherited iron build-up)	NHS says people with it are usually advised to avoid iron or vitamin C supplements.	Health agency guidance ²⁴
No test showing low iron	NHLBI says iron supplements are generally not given to people who do not have iron-deficiency anemia, because too much iron can damage organs. Ask a clinician for a blood test first.	Health agency guidance ²²
Pregnancy and breastfeeding	NHS names pregnancy as a very common cause of iron deficiency anemia and says untreated anemia raises the risk of complications before and after birth. MedlinePlus says pregnant and breastfeeding women need extra iron. NHS lists liver as an iron-rich food but says to avoid it in pregnancy. Ask a midwife or doctor about iron.	Health agency guidance ^{25 20 26 4}
Children	NHLBI says young children can develop iron-deficiency anemia if their diet lacks iron, usually between 9 months and 1 year. NHS warns that iron overdose in a young child can be fatal. Ask a paediatric clinician before giving any iron product.	Health agency guidance ^{21 25}
Kidney disease, bowel disease or other long-term conditions	NHLBI lists kidney disease and long-lasting inflammatory conditions as causes of iron-deficiency anemia that need their own care. See a clinician rather than self-treating.	Health agency guidance ²¹

Overdose, product quality and regulators

Body	Action	Date
NHS (UK) (United Kingdom)	Says iron tablets are recommended when a blood test shows low red blood cells, usually for about 6 months, with repeat blood tests; lists side effects; warns keep tablets away from children; says heavy periods and pregnancy are very common causes. source	2024-01
NHS (UK) (United Kingdom)	Vitamins and minerals: Iron. Lists food sources, says high doses can cause constipation, nausea, vomiting and stomach pain, and warns very high doses can be fatal, particularly in children. source	2020-08
National Heart, Lung, and Blood Institute (NHLBI, US NIH) (United States)	Says anemia may be a sign of a more serious condition and that iron supplements are generally not given to people without iron-deficiency anemia. source	2022-03

When to get medical help

Black, tar-like stools or blood in the stool, or heavy and lasting period bleeding: see a clinician soon, because bleeding is a common cause of iron loss.
Chest pain, feeling faint or being very short of breath: seek urgent care or call your local emergency number.
Tiredness that has lasted a few weeks without a clear reason, or comes with weight loss or mood changes: see a doctor for a blood test.
A child who may have swallowed iron tablets: call your local poison control centre or emergency services straight away.

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 are anemia and iron deficiency anemia?

Anemia means the blood has fewer healthy red blood cells than normal, so the body gets less oxygen-rich blood and you may feel tired or weak. Iron deficiency anemia, caused by too little iron, is the most common type. Only a clinician can say whether you have it.

^{23 25}

Does being tired mean I have low iron?

No. Tiredness has many causes, including poor sleep, sleep apnea, diabetes and an overactive thyroid. Only a blood test can show whether iron or red blood cells are low.

^{27 25}

How are anemia and iron deficiency tested?

A clinician usually orders a blood test called a full or complete blood count, and may also check hemoglobin, blood iron and ferritin. A newer 2026 hematology guideline sets ferritin thresholds so iron deficiency can be diagnosed even without anemia.

^{25 21 12}

What causes iron deficiency anemia?

NHS names heavy periods and pregnancy as very common causes, and bleeding in the stomach or bowel as another. Diets low in iron, trouble absorbing iron (for example with celiac disease) and some medicines can also play a part. If the reason is unclear a clinician may test further.

^{25 20 15}

Can I take iron for energy without a test?

It is better to test first. Iron has side effects, too much iron can harm people with conditions such as haemochromatosis, and NHLBI says iron is generally not given to people who are not iron deficient. Anemia can also be a sign of another problem.

^{22 24 23}

Does iron help tiredness when I am not anemic?

In women with unexplained tiredness and low ferritin, trials found iron reduced self-rated tiredness a little more than placebo, but not measured fitness. In one trial only women with ferritin at or below 50 micrograms per liter improved, which is why testing comes first.

^{18 17 7}

How long does iron treatment take?

When prescribed for iron deficiency anemia, NHS says tablets are usually taken for about 6 months, with repeat blood tests to check levels return to normal.

²⁵

Do vegetarians need to worry about iron?

Iron from plant foods is harder to absorb than iron from meat, and a 2010 review estimates 5 to 12 percent absorption on vegetarian diets versus 14 to 18 percent on mixed diets in people with no iron stores. A clinician or dietitian can advise if you are concerned.

^{9 26}

Do tea, coffee and herbal tea affect iron?

In a meal study, black tea, coffee, cocoa and herbal teas such as peppermint and chamomile all cut iron absorption. NHS lists tea, coffee and dairy among things to have less of when iron is low.

^{8 25}

Does vitamin C help iron work?

Vitamin C-rich foods help the body absorb iron, but adding vitamin C to iron pills raised hemoglobin only 0.14 g/dL in a 2024 review, which the authors called small and not clinically important.

^{21 3}

Do herbal or 'blood-building' products fix anemia?

No randomised trial of such a product for anemia was read for this page. A lab study also found many herbal teas lower iron absorption. Ask a clinician before relying on one.

⁸

When should I see a doctor?

See a clinician if you think you may have iron deficiency anemia, if tiredness has lasted a few weeks without a clear reason, or if you notice black stools or heavy bleeding. Seek urgent care for chest pain or fainting.

^{25 27 20}

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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: 2026-10-31
Last substantive update: 2026-10-31
How we research: We searched PubMed, re-read the abstract of every review and trial cited, and read the NHS, NHLBI and MedlinePlus pages directly. Full texts were not read. Certainty ratings are the compiler's own reading, except where a review gives its own grade (stated in the text). Funding is not stated in most abstracts, and this is noted where relevant.
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.

Sources 28

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

Abu Hashim H, Foda O, Ghayaty E. Lactoferrin or ferrous salts for iron deficiency anemia in pregnancy: A meta-analysis of randomized trials. Eur J Obstet Gynecol Reprod Biol. 2018. PMID 29059584. DOI 10.1016/j.ejogrb.2017.10.003. (abstract)
Collings R, Harvey LJ, Hooper L et al.. The absorption of iron from whole diets: a systematic review. Am J Clin Nutr. 2013. PMID 23719560. DOI 10.3945/ajcn.112.050609. (abstract)
Deng J, Ramelli L, Li PY et al.. Efficacy of vitamin C with Fe supplementation in patients with iron deficiency anemia: a systematic review and meta-analysis. Blood Vessel Thromb Hemost. 2024. PMID 40765927. DOI 10.1016/j.bvth.2024.100023. (abstract)
Finkelstein JL, Cuthbert A, Weeks J et al.. Daily oral iron supplementation during pregnancy. Cochrane Database Syst Rev. 2024. PMID 39145520. DOI 10.1002/14651858.CD004736.pub6. (abstract)
Garcia-Casal MN, Pasricha SR, Martinez RX et al.. Serum or plasma ferritin concentration as an index of iron deficiency and overload. Cochrane Database Syst Rev. 2021. PMID 34028001. DOI 10.1002/14651858.CD011817.pub2. (abstract)
Geerligs PD, Brabin BJ, Omari AA. Food prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries: a systematic review. J Hum Nutr Diet. 2003. PMID 12859709. DOI 10.1046/j.1365-277x.2003.00447.x. (abstract)
Houston BL, Hurrie D, Graham J et al.. Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials. BMJ Open. 2018. PMID 29626044. DOI 10.1136/bmjopen-2017-019240. (abstract)
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr. 1999. PMID 10999016. (abstract)
Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010. PMID 20200263. DOI 10.3945/ajcn.2010.28674F. (abstract)
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Pasricha SR, Tye-Din J, Muckenthaler MU et al.. Iron deficiency. Lancet. 2021. PMID 33285139. DOI 10.1016/S0140-6736(20)32594-0. (abstract)
Powers JM, Lim MY, Achebe MO et al.. American Society of Hematology 2026 guidelines for diagnosis of iron deficiency. Blood Adv. 2026. PMID 42747316. DOI 10.1182/bloodadvances.2025015950. (abstract)
Sharieff W, Dofonsou J, Zlotkin S. Is cooking food in iron pots an appropriate solution for the control of anaemia in developing countries? A randomised clinical trial in Benin. Public Health Nutr. 2008. PMID 17935647. DOI 10.1017/S1368980007001139. (abstract)
Skolmowska D, Głąbska D, Kołota A et al.. Effectiveness of Dietary Interventions in Prevention and Treatment of Iron-Deficiency Anemia in Pregnant Women: A Systematic Review of Randomized Controlled Trials. Nutrients. 2022. PMID 35893877. DOI 10.3390/nu14153023. (abstract)
Snook J, Bhala N, Beales ILP et al.. British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults. Gut. 2021. PMID 34497146. DOI 10.1136/gutjnl-2021-325210. (abstract)
Stoffel NU, Cercamondi CI, Brittenham G et al.. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials. Lancet Haematol. 2017. PMID 29032957. DOI 10.1016/S2352-3026(17)30182-5. (abstract)
Vaucher P, Druais PL, Waldvogel S et al.. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012. PMID 22777991. DOI 10.1503/cmaj.110950. (abstract)
Verdon F, Burnand B, Stubi CL et al.. Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial. BMJ. 2003. PMID 12763985. DOI 10.1136/bmj.326.7399.1124. (abstract)
da Silva Lopes K, Yamaji N, Rahman MO et al.. Nutrition-specific interventions for preventing and controlling anaemia throughout the life cycle: an overview of systematic reviews. Cochrane Database Syst Rev. 2021. PMID 34564844. DOI 10.1002/14651858.CD013092.pub2. (abstract)
. MedlinePlus Medical Encyclopedia: Iron deficiency anemia (review date 1 April 2025). . . (full-text)
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. NHS: Haemochromatosis (overview page). . . (full-text)
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. NHS: Vitamins and minerals - Iron (page last reviewed 3 August 2020). . . (full-text)
. NHS: Tiredness and fatigue (page last reviewed 2 June 2023). . . (full-text)
von Siebenthal HK, Gessler S, Vallelian F et al.. Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. EClinicalMedicine. 2023. PMID 38021373. DOI 10.1016/j.eclinm.2023.102286. (abstract)

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.