Flaxseed Oil and Plant Omega-3 (ALA)

Q: What is flaxseed oil?

It is the oil pressed from flax seeds. It is the richest plant source of ALA, an essential omega-3 fat, according to MedlinePlus.

Q: What is ALA?

Alpha-linolenic acid is an omega-3 fat the body cannot make. It is different from EPA and DHA, which are found in fish and algae.

Q: Is flaxseed oil as good as fish oil?

No, they are different. The body turns only a small share of ALA into EPA and very little into DHA. Only ready-made DHA reliably raises blood DHA.

Q: What foods have plant omega-3?

By USDA data, flaxseed oil has the most (about 7.3 g ALA per tablespoon), then chia seeds (5.1 g per ounce), walnuts (2.6 g per ounce), ground flaxseed, walnut oil and canola oil.

Q: Does flaxseed oil help the heart?

A Cochrane review found that more ALA probably makes little or no difference to deaths and may slightly lower cardiovascular events, with low certainty. Trials did not test flaxseed oil alone.

Q: Does it lower blood pressure or cholesterol?

Results are mixed. One review found slightly lower blood pressure and triglycerides but slightly higher LDL cholesterol; another found no blood pressure change.

Q: Does it help with diabetes?

A review of 8 small trials in type 2 diabetes found no change in HbA1c or fasting glucose. One small gestational diabetes trial reported benefits but carries a journal expression of concern.

Q: Does it help skin or ADHD?

One very small trial reported better skin sensitivity and dryness. A small trial in children with ADHD found no difference from placebo, and most children dropped out.

Q: Does flaxseed oil raise cancer risk?

No clear link to prostate cancer was found in a 2013 review. A large 2021 review of cohort studies found slightly more cancer deaths with high ALA intake (RR 1.06). Both are observational.

Q: Is it safe with blood thinners?

NCCIH says flaxseed oil might interact with anticoagulant or antiplatelet drugs, and calls this theoretical. Ask a pharmacist or doctor first.

Alpha-linolenic acid (ALA); oil of Linum usitatissimum · also called Flax oil, linseed oil, plant omega-3, aceite de linaza, omega-3 vegetal

Flaxseed oil is the richest plant source of ALA, an essential omega-3 fat. The body turns only a small part of ALA into the fish-type omega-3s EPA and DHA. Large reviews find little or no effect on deaths and at most a small effect on heart events; results for blood pressure, blood sugar and skin are mixed or from tiny trials. It spoils easily, and may matter for people on blood thinners, so ask a doctor or pharmacist.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Flaxseed Oil and Plant Omega-3 (ALA)

Flaxseed oil is pressed from flax seeds and is the richest plant source of ALA, an essential omega-3 fat. Reviews find little or no effect on deaths, mixed results on blood markers, and only small trials for skin and gestational diabetes.

What flaxseed oil and ALA are

ALA (alpha-linolenic acid) is an omega-3 fat the body cannot make, so it must come from food. Flaxseed oil is pressed from the seeds of the flax plant (Linum usitatissimum). MedlinePlus says ground flaxseeds and flaxseed oil have the most ALA of any plant food.

ALA is a different fat from EPA and DHA, the omega-3s found in fish and algae. Flaxseed oil also carries some of the omega-6 fat linoleic acid, about 14 g per 100 g by USDA data, and no EPA or DHA.

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Where plant omega-3 comes from

By USDA data, ALA per portion: flaxseed oil about 7.3 g per tablespoon; dried chia seeds about 5.1 g per ounce; English walnuts about 2.6 g per ounce; ground flaxseed about 1.6 g per tablespoon; walnut oil about 1.4 g, canola oil about 1.3 g and soybean oil about 0.9 g per tablespoon. The Linus Pauling Institute table gives the same figures.

The US National Academy of Medicine set adequate intakes of ALA in 2002: 1.6 g a day for men and 1.1 g for women aged 19 and over, 1.4 g in pregnancy and 1.3 g while breastfeeding. These are food targets for the public, not advice to take supplements.

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Can the body turn ALA into fish-type omega-3?

Only a little. Reviews say ALA raises blood EPA but has little effect on blood DHA, and that preformed DHA is needed to raise blood DHA. The Linus Pauling Institute quotes about 8% of ALA to EPA in young men and about 21% in young women, and 0 to 4% and about 9% to DHA.

This is why flaxseed oil is not a like-for-like swap for fish, krill or algae oil, which have their own pages.

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What the research shows

Cochrane's 2020 review found that more ALA probably makes little or no difference to deaths, may slightly lower cardiovascular events (low certainty) and probably slightly lowers irregular heartbeat (from 2 trials). The largest ALA trial, in 4,837 heart attack survivors, did not reach significance (hazard ratio 0.91, 0.78 to 1.05). Large observational studies link more ALA to fewer deaths, but these cannot show cause.

For blood pressure, blood fats, inflammation and blood sugar, results are small and mixed. Skin, gestational diabetes, dialysis, children's attention and thinking each rest on one small trial or a thin review. One gestational diabetes trial has a journal expression of concern.

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Oil versus the whole seed

The oil is the fat part of the seed. It gives ALA but not the fibre or lignans of ground flaxseed. Most ALA trials used margarine, mixed foods or mixed plant sources, so their results do not map neatly onto flaxseed oil pills.

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At a glance

Traditional uses history, not proof

Flaxseed has a long history of traditional use, including as a laxative (NCCIH)
Today sold as an oil or capsule for heart, brain and immune health

Studied for research

Essential nutrient and food sources, high certainty
Conversion to EPA and DHA (limited), moderate certainty
Heart and blood vessel events, low certainty
Blood pressure and blood fats, low certainty
Inflammation markers and type 2 diabetes markers, mixed or low certainty
Skin, gestational diabetes, dialysis, children's attention, thinking, cancer risk, very low certainty

Main compounds

Alpha-linolenic acid (ALA)
Linoleic acid (omega-6, also in the oil)

Common forms

Bottled flaxseed oil
Flaxseed oil capsules
Ground flaxseed and other ALA foods (walnuts, chia, canola oil)

Research links: 2020 Cochrane review: omega-3 fats and heart disease (86 trials) · 2010 Alpha Omega trial: ALA margarine after a heart attack · 2021 BMJ review: dietary ALA and deaths (41 cohorts) · 2009 review: ALA conversion to EPA and DHA · NCCIH: Flaxseed and Flaxseed Oil · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Alpha-linolenic acid (ALA, 18:3 n-3), an essential omega-3 fat; flaxseed oil is the oil pressed from the seeds of Linum usitatissimum
Synonyms: ALA; alpha-linolenic acid; linseed oil (the oil)
Common names: Flaxseed oil (English); Flax oil (English); Linseed oil (English); Plant omega-3 (English); Aceite de linaza (Spanish); Aceite de lino (Spanish); Omega-3 vegetal (Spanish); Ácido alfa-linolénico (Spanish)
Family or group: Omega-3 fatty acids (plant source). MedlinePlus separates ALA from the fish omega-3s EPA and DHA.
Classification: Plantae > Malpighiales > Linaceae > Linum > Linum usitatissimum L.
Native range: Not researched for this page.
What it looks like: Fruit: The seeds are pressed for the oil; see the flaxseed food page.
Harvest and processing: Not read from a source beyond 'extracted from flaxseed' (NCCIH).
Look-alikes and adulterants: Name: Ground flaxseed; Note: The whole food. It adds fibre and lignans that the oil lacks; it has its own page.; Name: Fish oil, krill oil, cod liver oil and algal oil; Note: These supply EPA and DHA directly. ALA from flaxseed oil is a different fat.; Name: Chia seed, walnut, canola, soybean and hemp oils; Note: Other plant sources of ALA, with less per tablespoon than flaxseed oil by USDA data.
Sustainability and conservation: Not assessed.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
		NCCIH

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
Alpha-linolenic acid (ALA) PubChem 5280934	omega-3 polyunsaturated fatty acid, 18 carbons	Seed oil 53.4 g per 100 g of flaxseed oil (USDA SR Legacy)	Essential fat; starting material for EPA and DPA in the body. ^{23 2}	Human data
Linoleic acid (LA) PubChem 5280450	omega-6 polyunsaturated fatty acid	Seed oil About 14.3 g per 100 g of flaxseed oil (USDA SR Legacy)	Essential omega-6 fat that sits alongside ALA in the oil; its role was not examined further in the sources read. ²³	Human data
Eicosapentaenoic acid (EPA) PubChem 446284	omega-3, 20 carbons	Not present in flaxseed oil 0 in flaxseed oil (USDA SR Legacy)	Made in small amounts from ALA. ^{3 2}	Human data
Docosahexaenoic acid (DHA) PubChem 445580	omega-3, 22 carbons	Not present in flaxseed oil 0 in flaxseed oil (USDA SR Legacy)	Made in very small amounts from ALA. ^{3 2}	Human data

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Conversion of ALA to EPA, DPA and DHA	Not specified in the sources read	Tracer and supplement studies show a limited conversion: ALA raises blood EPA and DPA, but blood DHA changes little. Women convert more than men. ^{2 3 18}	Human data
Effects on blood fats, blood pressure and inflammation	Not established	Reviews of trials report small, inconsistent changes in these markers. No mechanism was established in the sources read. ^{16 14 10}	Human data

Absorption, metabolism and elimination

Absorption: Not described in the sources read.
Distribution: Not described in the sources read.
Metabolism: ALA is partly converted to EPA, DPA and a little DHA. The Linus Pauling Institute quotes about 8% to EPA and 0 to 4% to DHA in young men and about 21% to EPA and 9% to DHA in young women.
Elimination: Not described in the sources read. A 2005 review says a lower share of ALA is burned for energy in women than in men.
Bioavailability: Not described beyond the conversion figures.

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Isolated compounds versus whole extracts

Flaxseed oil is the fat part of the seed. It gives ALA but not the fibre and lignans in ground flaxseed. Most ALA trials used mixed foods and oils, not flaxseed oil alone, so results for pills and for whole seeds are not interchangeable.

Nutritional composition

ALA amounts are from USDA FoodData Central SR Legacy (April 2018), read from a saved local copy and matched to the Linus Pauling Institute table: flaxseed oil 7.3 g per tablespoon, chia seeds 5.1 g per ounce, English walnuts 2.6 g per ounce (total 18:3 fat), ground flaxseed 1.6 g per tablespoon, walnut oil 1.4 g, canola oil 1.3 g and soybean oil 0.9 g per tablespoon.

14benefits and uses looked at

23studies and sources checked

High certaintybest evidence rating found

6lab markers tracked in trials

2 high certainty1 moderate certainty1 mixed findings4 low certainty5 very low certainty1 not enough evidence

What was looked at

The 14 benefits and uses checked for Flaxseed Oil and Plant Omega-3 (ALA), each with how strong the evidence is. Tap one to open it.

Essential omega-3 fat (ALA) and how much is eatenHigh certainty
Food sources of plant omega-3 (ALA)High certainty
Making fish-type omega-3s (EPA and DHA) from ALAModerate certainty
Heart and blood vessel eventsLow certainty
Deaths in long-term observational studiesLow certainty
Blood pressure and blood fatsLow certainty
Inflammation markers (CRP, TNF, IL-6)Mixed findings
Blood sugar in type 2 diabetesLow certainty
Blood sugar in gestational diabetesVery low certainty
Blood fats and CRP in people on dialysisVery low certainty
Skin sensitivity and drynessVery low certainty
ADHD symptoms in childrenVery low certainty
Thinking and memoryNot enough evidence
Prostate cancer and cancer deathsVery low certainty

Lab markers tracked in the studies

Blood EPA and DHA levelsSystolic blood pressureTriglycerides and LDL cholesterolC-reactive protein (CRP)HbA1c and fasting glucoseWater loss through the skin (TEWL)

What is Flaxseed Oil and Plant Omega-3 (ALA) good for?

The main studied uses and how strong the human evidence is for each. Most trials tested ALA-rich foods or mixed plant sources, not flaxseed oil alone.

Essential omega-3 fat (ALA) and how much is eatenHigh certaintyALA is an essential fat the body cannot make. The US adequate intake is 1.6 g a day for men and 1.1 g for women (a food target set in 2002, not advice to take pills). Flaxseed oil is the richest plant source. Food sources of plant omega-3 (ALA)High certaintyBy USDA data, a tablespoon of flaxseed oil has about 7.3 g of ALA. An ounce of chia seeds has about 5.1 g, an ounce of walnuts about 2.6 g and a tablespoon of ground flaxseed about 1.6 g. Canola oil has about 1.3 g a tablespoon. Making fish-type omega-3s (EPA and DHA) from ALAModerate certaintyThe body turns only a small share of ALA into EPA and very little into DHA. Reviews say only ready-made DHA reliably raises blood DHA, so flaxseed oil is not a swap for fish or algae oil. Heart and blood vessel eventsLow certaintyLarge reviews find ALA probably makes little or no difference to deaths. It may slightly lower cardiovascular events (low certainty) and probably slightly lowers irregular heartbeat (2 trials). The main ALA trial in heart attack survivors found no significant effect. Deaths in long-term observational studiesLow certaintyIn 41 follow-up studies, people who ate more ALA had about 10% lower risk of death from any cause, with fewer heart deaths but slightly more cancer deaths. These studies cannot show cause. Blood pressure and blood fatsLow certaintyA 2023 review found slightly lower blood pressure and triglycerides but slightly higher LDL cholesterol with plant ALA in people with overweight. A 2024 review with 3 flaxseed oil trials found no blood pressure change. Inflammation markers (CRP, TNF, IL-6)Mixed findingsA 25-trial review found no effect on inflammation markers, and healthy people might see CRP rise. A smaller review in people with overweight found lower CRP and TNF-alpha. Results are mixed. Blood sugar in type 2 diabetesLow certaintyA review of 8 small trials (212 people) found no change in HbA1c, fasting glucose or insulin. The trials differed a lot and the authors say firm conclusions are not possible. Blood sugar in gestational diabetesVery low certaintyOne small 6-week trial in 60 women reported better blood sugar markers with flaxseed oil capsules, but the journal has since published an expression of concern about it. Treat it cautiously. Blood fats and CRP in people on dialysisVery low certaintyA 2024 review reported lower triglycerides and CRP in people on dialysis, but results differed hugely between trials. It applies only to people on dialysis. Skin sensitivity and drynessVery low certaintyOne very small 12-week trial (26 women) reported less skin sensitivity and dryness with flaxseed oil. No numbers were given in the abstract and no other human trial was read. ADHD symptoms in childrenVery low certaintyAn 8-week trial in 40 children with ADHD found no difference from placebo, but only 17 finished, so it cannot rule a benefit in or out. Thinking and memoryNot enough evidenceA 2022 review calls ALA and thinking an early-stage topic with promising signs. No trial of flaxseed oil alone for memory was read. Prostate cancer and cancer deathsVery low certaintyReviews of observational studies found no clear link between ALA and prostate cancer, and one large review found slightly more cancer deaths with high ALA intake (RR 1.06). The evidence is mixed.

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.

Essential omega-3 fat (ALA) and how much is eaten

High certainty

ALA (alpha-linolenic acid) is an omega-3 fat the body cannot make, so it has to come from food. The US National Academy of Medicine sets an adequate intake of 1.6 g a day for men and 1.1 g a day for women aged 19 and over. Flaxseed oil is the richest plant source of ALA.

2 studiesDietary ALA from food and from flaxseed oil; forms are not compared h…

Studies, doses and limits

What the trials found

The Linus Pauling Institute lists the US adequate intakes for ALA (set by the Food and Nutrition Board in 2002): babies 0.5 g a day; children 0.7 g (1 to 3 years), 0.9 g (4 to 8), 1.2 g (boys 9 to 13) or 1.0 g (girls 9 to 13); teens and adults 1.6 g for males and 1.1 g for females; pregnancy 1.4 g; breastfeeding 1.3 g. These are intake targets for the general population set by a regulator body, not advice to take a supplement. MedlinePlus says ground flaxseeds and flaxseed oil have the most ALA of all plant foods. No trial was read in which flaxseed oil corrected a measured ALA deficiency.

Results

ALA is essential and flaxseed oil is a concentrated source. That does not show that a flaxseed oil pill is needed or that it treats any condition.

Effect sizes as reported

No effect sizes apply: these are intake targets and nutrient roles.

Why this rating

High that ALA is an essential fat and that the adequate-intake figures are as published (Linus Pauling Institute, citing the National Academy of Medicine, 2002; MedlinePlus). Not a trial result for any supplement.

Form and dose studied

Dietary ALA from food and from flaxseed oil; forms are not compared here.

Who was studied

General population.

Limits

The figures are from 2002. The NIH Office of Dietary Supplements fact sheet, which would give a second source, could not be read (blocked). No official upper limit for ALA was found in the sources read.

Why researchers looked

People ask whether they get enough plant omega-3 and whether flaxseed oil is the way to get it.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Established nutrition

ALA is an essential fatty acid and the starting material the body can use to make longer omega-3 fats (see the conversion entry). This is established nutrition, described by the Linus Pauling Institute.

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

See the Safety tab. Official intake figures are not a reason to take pills.

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Food sources of plant omega-3 (ALA)

High certainty

Per USDA data, one tablespoon of flaxseed oil has about 7.3 g of ALA. An ounce of dried chia seeds has about 5.1 g, an ounce of English walnuts about 2.6 g (total 18:3 fat), a tablespoon of ground flaxseed about 1.6 g, a tablespoon of walnut oil about 1.4 g, canola oil about 1.3 g and soybean oil about 0.9 g.

3 studiesFoods and oils only. This is not a recommendation to eat any food or …

Studies, doses and limits

What the trials found

USDA FoodData Central SR Legacy lists ALA or total 18:3 fat per 100 g. Flaxseed oil 53.4 g per 100 g; chia seeds 17.8 g; English walnuts 9.1 g; walnut oil 10.4 g; canola oil 9.1 g; soybean oil 6.8 g; hulled hemp seed 8.7 g; olive oil 0.8 g. Converted to household portions: flaxseed oil 13.6 g per tablespoon gives 7.3 g; chia 28.35 g per ounce gives 5.1 g; walnuts 28.35 g per ounce gives 2.6 g; ground flaxseed 7 g per tablespoon gives 1.6 g (whole flaxseed 10.3 g per tablespoon gives 2.3 g); walnut oil about 1.4 g; canola 14 g per tablespoon gives 1.3 g; soybean oil about 0.9 g. The same flaxseed oil has about 14.3 g of the omega-6 fat linoleic acid per 100 g, and USDA lists no EPA or DHA in it. The Linus Pauling Institute table lists the same portion figures. No trial compared food ALA with oil pills for health results.

Results

Flaxseed oil is by far the most concentrated source, ahead of chia seeds and walnuts. None of these foods contains EPA or DHA.

Effect sizes as reported

Per 100 g and per portion, as above. Flaxseed oil 7.3 g ALA per tablespoon; chia 5.1 g per ounce; walnuts 2.6 g per ounce; ground flaxseed 1.6 g per tablespoon; canola oil 1.3 g per tablespoon.

Why this rating

High that foods contain these amounts (USDA tables, matching a second reference). How much the body absorbs and uses was not measured in the sources read.

Form and dose studied

Foods and oils only. This is not a recommendation to eat any food or take any oil.

Who was studied

General adult diet.

Limits

SR Legacy values are from a 2018 release. Oil batches, seed varieties and storage change the content. The flaxseed and flaxseed oil food pages cover the foods themselves.

Why researchers looked

Many people want to know which plant foods give ALA and how flaxseed oil compares.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Nutrient database

These are nutrient amounts taken from USDA tables.

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

Flaxseed oil spoils easily; see the Safety tab.

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Making fish-type omega-3s (EPA and DHA) from ALA

Moderate certainty

The body can turn some ALA into the longer omega-3 fats EPA and DHA, but not much. Reviews say ALA raises blood EPA a little, has little effect on blood DHA, and that only DHA taken ready-made reliably raises blood DHA. Women convert more than men.

3 studiesALA from flaxseed oil or other plant oils, compared with preformed DH…

Studies, doses and limits

What the trials found

A 2009 society working-group review (Brenna and colleagues) says that in healthy adults on Western diets ALA supplements raise blood EPA and DPA but have little effect on DHA, whereas preformed DHA is effective; it concludes that blood DHA status improves with preformed DHA but not with ALA, EPA or other precursors. A 2005 review (Burdge and Calder) says conversion to EPA is limited in men and conversion to DHA is very low, and that women convert more, possibly because of oestrogen. The Linus Pauling Institute quotes tracer figures: about 8% of ALA to EPA and 0 to 4% to DHA in young men; about 21% to EPA and 9% to DHA in young women. No trial of flaxseed oil on thinking, eyes or heart that depended on this conversion was read.

Results

Flaxseed oil is not a like-for-like swap for fish or algae oil. It gives a modest rise in EPA and little or no rise in DHA.

Effect sizes as reported

Tracer figures from the Linus Pauling Institute: men about 8% to EPA and 0 to 4% to DHA; women about 21% to EPA and 9% to DHA. The two reviews give no numbers in their abstracts.

Why this rating

Moderate: consistent across two reviews and tracer studies, but the reviews are narrative and the tracer studies are small.

Form and dose studied

ALA from flaxseed oil or other plant oils, compared with preformed DHA or EPA.

Who was studied

Healthy adults, mostly young; pregnant women and infants are discussed in the reviews.

Limits

Narrative reviews read from abstracts; older (2005 and 2009). Tracer figures come from the Linus Pauling Institute page (2019) and were not checked against the original studies.

Why researchers looked

Plant-based eaters ask whether flaxseed oil can replace fish oil.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Human physiology

The body lengthens and unsaturates ALA step by step into EPA, DPA and DHA. Tracer studies in people show the process is limited. This is human physiology described in two reviews.

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

None specific.

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Heart and blood vessel events

Low certainty

Large reviews find that eating more ALA probably makes little or no difference to deaths. It may slightly lower cardiovascular events (low certainty) and probably slightly lowers irregular heartbeat (moderate certainty, from only 2 trials). In the biggest ALA trial, in people who had had a heart attack, ALA margarine did not significantly reduce events.

4 studiesMostly ALA-enriched foods (margarine, oils) and supplements; flaxseed…

Studies, doses and limits

What the trials found

The 2020 Cochrane review (86 trials, 162,796 people; 5 trials of ALA with 19,327 people) found for ALA: all-cause deaths RR 1.01 (moderate certainty), cardiovascular deaths RR 0.96 (moderate), coronary heart disease events RR 1.00 (low), cardiovascular events RR 0.95 (low; 0.91 in low-bias trials), arrhythmia RR 0.73 (moderate, 2 trials). The Alpha Omega trial (4,837 heart-attack survivors, 40 months) gave about 1.9 g ALA a day in margarine: hazard ratio 0.91 (0.78 to 1.05) for major cardiovascular events; in women 0.73 (0.51 to 1.03), a subgroup that did not reach significance. A 2022 review says three trials of ALA-rich diets showed benefit, but the one designed for ALA alone showed only a trend. MedlinePlus says ALA benefits the heart but not as directly as EPA and DHA.

Results

Little or no effect on deaths; a possible small cut in cardiovascular events and irregular heartbeat, but the numbers include no effect.

Effect sizes as reported

Cochrane, ALA: all-cause deaths RR 1.01 (0.84 to 1.20); cardiovascular events RR 0.95 (0.83 to 1.07); arrhythmia RR 0.73 (0.55 to 0.97). Alpha Omega: HR 0.91 (0.78 to 1.05).

Why this rating

Low for cardiovascular events (Cochrane's own rating); moderate that there is little or no effect on deaths. The ALA trials mostly used enriched foods such as margarine, not flaxseed oil.

Form and dose studied

Mostly ALA-enriched foods (margarine, oils) and supplements; flaxseed oil alone was not the main form tested.

Who was studied

Adults at varying heart risk, including people after a heart attack.

Limits

Only 5 trials tested ALA. Amounts of extra ALA were small in the largest trial. Cochrane authors report no conflicts; the Alpha Omega trial was funded by the Netherlands Heart Foundation and others.

Why researchers looked

ALA is promoted as a heart-friendly plant fat, so researchers have tested it against usual diets.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Preliminary mechanism

ALA may act through blood fats, blood pressure and inflammation, but these links are modest and not proved. This is a suggestion, not an established mechanism.

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

Not a substitute for heart medicines. Ask a doctor before changing treatment.

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Deaths in long-term observational studies

Low certainty

In 41 follow-up studies of over a million adults, people who ate more ALA had a lower risk of dying from any cause (10% lower), from cardiovascular disease and from coronary heart disease. These studies cannot show that ALA caused the difference.

1 studiesDietary ALA from foods; supplements were not the exposure.

Studies, doses and limits

What the trials found

A 2021 BMJ meta-analysis of 41 cohorts (1,197,564 people; 198,113 deaths; follow-up 2 to 32 years) found high versus low ALA intake went with lower risk of death from any cause (RR 0.90, 0.83 to 0.97), cardiovascular disease (0.92, 0.86 to 0.99) and coronary heart disease (0.89, 0.81 to 0.97). Each extra 1 g a day of ALA (about one tablespoon of canola oil or half an ounce of walnuts, as the authors put it) went with about 5% lower risk of all-cause and cardiovascular death. Cancer deaths were slightly higher (RR 1.06, 1.02 to 1.11; see the Benefits section on cancer). Higher blood ALA went with fewer all-cause and coronary deaths.

Results

A consistent link to fewer deaths from heart disease in observational studies, with a small signal for more cancer deaths. Not proof that flaxseed oil pills help.

Effect sizes as reported

All-cause RR 0.90 (0.83 to 0.97), I2 78%; cardiovascular RR 0.92 (0.86 to 0.99); coronary heart disease RR 0.89 (0.81 to 0.97); per 1 g a day RR 0.95 (0.91 to 0.99) for all-cause deaths.

Why this rating

Low: observational, with large differences between studies for all-cause deaths (I2 78%). The foods behind ALA intake were mostly walnuts and plant oils, not flaxseed oil supplements.

Form and dose studied

Dietary ALA from foods; supplements were not the exposure.

Who was studied

Adults in prospective cohorts, mostly in high-income countries.

Limits

Cannot prove cause. Diet questionnaires are imprecise. The authors report no relevant financial relationships.

Why researchers looked

Researchers compare people who eat more and less ALA over many years to see who lives longer.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Observational association

Observational links cannot show cause. People who eat more ALA-rich foods such as walnuts may also have other healthy habits.

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

See the cancer entry and the Safety tab.

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Blood pressure and blood fats

Low certainty

A 2023 review of 19 trials in people with overweight or obesity found plant ALA lowered systolic blood pressure, triglycerides, CRP and TNF-alpha slightly, but raised LDL cholesterol slightly. A 2024 review that included only 3 flaxseed oil trials found no change in blood pressure.

3 studiesFlaxseed and flaxseed oil in the 2023 review; olive oil and flaxseed …

Studies, doses and limits

What the trials found

The 2023 meta-analysis (19 trials, 1,183 adults with overweight or obesity; flaxseed, flaxseed oil and other plant sources) found lower systolic blood pressure (SMD -0.37, -0.66 to -0.08), triglycerides (SMD -4.41, -5.99 to -2.82), CRP and TNF-alpha, but higher LDL cholesterol (SMD 1.32, 0.05 to 2.59); no clear change in diastolic pressure, total cholesterol, HDL or IL-6. The effect was stronger in the subgroup with 3 g ALA a day or more from flaxseed products, with trials of 12 weeks or longer and when the starting profile was poor. A 2024 meta-analysis of 17 trials (14 olive oil, 3 flaxseed oil) in healthy or at-risk adults found no significant effect on systolic pressure (-0.48 mmHg, -1.76 to 0.80) or diastolic pressure (-0.47 mmHg, -1.33 to 0.39). The Cochrane review found little or no effect of ALA on lipids and blood pressure.

Results

Mixed and small. Possible slight falls in blood pressure and triglycerides in some groups, offset by a slight rise in LDL cholesterol in one review; the flaxseed-oil-only evidence is thin.

Effect sizes as reported

2023 review: systolic BP SMD -0.37; triglycerides SMD -4.41; LDL SMD +1.32. 2024 review (3 flaxseed oil trials): systolic BP -0.48 mmHg (not significant).

Why this rating

Low: results differ between reviews, effects are small, and the flaxseed oil trials are few (3 in one review).

Form and dose studied

Flaxseed and flaxseed oil in the 2023 review; olive oil and flaxseed oil in the 2024 review.

Who was studied

Adults with overweight or obesity (2023); healthy and at-risk adults (2024).

Limits

Mixed sources in the larger review. Units for the pooled effects are unusual in the abstract. The Cochrane review found no clear effect on lipids or pressure.

Why researchers looked

Blood pressure and cholesterol are common reasons people try flaxseed oil.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Preliminary mechanism

Possible effects on blood fats and vessel tone are suggested but not established in people.

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

A slight LDL rise was reported in one review. Do not replace blood pressure or cholesterol medicines with oil.

^{16 10 1}

Inflammation markers (CRP, TNF, IL-6)

Mixed findings

A 25-trial review found no benefit of dietary ALA on inflammation markers, and healthy people might even see CRP rise. A smaller 2023 review in people with overweight found lower CRP and TNF-alpha. Results are mixed.

3 studiesDietary ALA from foods and supplements, including flaxseed oil in a m…

Studies, doses and limits

What the trials found

The 2018 meta-analysis of 25 trials found no significant effect on TNF (SMD -0.03, -0.36 to 0.29), IL-6 (-0.17, -0.46 to 0.12), CRP (-0.06, -0.24 to 0.12), sICAM-1 or sVCAM-1; in healthy subjects ALA might increase CRP, and the effect on CRP was related to baseline level. The 2023 review of 19 trials in adults with overweight or obesity found lower CRP (SMD -0.38, -0.72 to -0.04) and TNF-alpha (SMD -0.45, -0.73 to -0.17) but no change in IL-6. A 2024 review with 3 flaxseed oil trials found no significant change in CRP or IL-6.

Results

No consistent effect. Possible small falls in people with overweight, none overall.

Effect sizes as reported

2018: CRP SMD -0.06 (-0.24 to 0.12). 2023 (overweight): CRP SMD -0.38 (-0.72 to -0.04). 2024: CRP mean difference 0.11 (-1.18 to 0.40).

Why this rating

Mixed: three reviews point different ways, and markers are not illnesses.

Form and dose studied

Dietary ALA from foods and supplements, including flaxseed oil in a minority of trials.

Who was studied

Healthy adults and adults with overweight or obesity.

Limits

Different trial mixes in each review. Marker levels are not clinical outcomes.

Why researchers looked

ALA is often promoted as anti-inflammatory, so trials measured blood markers of inflammation.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Preliminary mechanism

Lab and human work suggest omega-3 fats can shift inflammatory signals, but this was not established for ALA in the sources read.

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

In healthy people CRP might rise slightly (2018 subgroup finding).

^{14 16 10}

Blood sugar in type 2 diabetes

Low certainty

A 2017 review of 8 small trials found ALA-enriched diets did not change HbA1c, fasting glucose or fasting insulin. The authors say there are too few trials to be sure and that higher intakes may work differently.

2 studiesALA-enriched diets (median 4.4 to 5.4 g ALA a day, as studied in tria…

Studies, doses and limits

What the trials found

The meta-analysis pooled 8 randomised trials (212 people with type 2 diabetes, at least a month long). At a median of 4.4 g a day of ALA for a median of 3 months HbA1c did not change (MD -0.01%, -0.32 to 0.31). At a median of 5.4 g a day fasting glucose (MD 0.07, -0.61 to 0.76) and fasting insulin (MD 7.03, -5.84 to 19.89) did not change. Differences between trials were large and unexplained (I2 75% or more). Higher intake was linked to bigger falls in HbA1c and glucose in subgroup analysis, and a statistical adjustment for missing small studies gave an HbA1c change of -0.25% (-0.38 to -0.12). NCCIH says it is unclear whether flaxseed oil helps other people with diabetes.

Results

No clear effect on blood sugar. Too few small trials to be sure.

Effect sizes as reported

HbA1c MD -0.01% (-0.32 to 0.31); fasting glucose MD 0.07 (-0.61 to 0.76).

Why this rating

Low: few small trials, with large unexplained differences between them.

Form and dose studied

ALA-enriched diets (median 4.4 to 5.4 g ALA a day, as studied in trials).

Who was studied

Adults with type 2 diabetes.

Limits

Only 8 trials, 212 people. Review authors disclose past funding from food-industry and public bodies; none is linked to this review in the abstract.

Why researchers looked

Omega-3 fats have been studied for insulin sensitivity.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Not established

Not established. The review notes a possible dose-dependent effect that needs more trials.

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

People with diabetes who take medicines should ask their doctor before adding supplements.

^{8 20}

Blood sugar in gestational diabetes

Very low certainty

One small 6-week trial in 60 women with gestational diabetes reported lower fasting glucose, insulin resistance and triglycerides with flaxseed oil capsules. The journal has since published an expression of concern about this paper, so it should be treated cautiously. NCCIH says research is limited.

3 studiesFlaxseed-oil capsules with 400 mg ALA each, 2 a day for 6 weeks.

Studies, doses and limits

What the trials found

The randomised, double-blind trial gave 60 women with gestational diabetes flaxseed-oil capsules (400 mg ALA each, 2 a day) or placebo for 6 weeks. The abstract reports lower fasting glucose (P=0.001), insulin (P=0.001) and insulin resistance (P<0.001), lower triglycerides (P<0.001) and CRP (P=0.006), and changes in gene activity. No effect sizes are in the abstract. On 14 January 2022 the journal published an expression of concern about the paper; the notice record read does not give the reason. NCCIH says some research suggests flaxseed oil with ALA might improve fasting measures and insulin resistance in pregnant people with gestational diabetes, but research is limited.

Results

A positive lab-marker result from one small trial that carries a journal concern. Not enough to rely on.

Effect sizes as reported

P values only in the abstract: fasting glucose P=0.001; insulin resistance P<0.001; CRP P=0.006.

Why this rating

Very low: one small trial of 6 weeks, no effect sizes in the abstract, lab markers only, and an expression of concern.

Form and dose studied

Flaxseed-oil capsules with 400 mg ALA each, 2 a day for 6 weeks.

Who was studied

Women with gestational diabetes.

Limits

Pregnancy is a time to avoid unproven supplements. A journal expression of concern applies. Pregnancy safety of flaxseed oil is uncertain (NCCIH); see the Safety tab.

Why researchers looked

Gestational diabetes puts pregnancy at risk, so people look for dietary help.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Preliminary mechanism

The trial reported changes in genes linked to insulin, fats and inflammation. These are lab markers, and the trial is under a journal concern.

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

Pregnant women should not start flaxseed oil on their own. Ask a doctor or midwife.

^{6 7 20}

Blood fats and CRP in people on dialysis

Very low certainty

A 2024 review reported lower triglycerides and CRP with flaxseed oil in people having haemodialysis, but results differed hugely between trials (I2 above 90%).

1 studiesFlaxseed oil as studied; higher amounts (over 10 g a day) were linked…

Studies, doses and limits

What the trials found

The meta-analysis of randomised trials in haemodialysis patients reported triglycerides lower by 85.78 mg/dL (95% CI -155.24 to -16.32, I2 98%) and CRP lower by 2.66 mg/L (-4.07 to -1.24, I2 92%). Subgroup changes in LDL, HDL and total cholesterol appeared only in trials giving over 10 g a day. No effect on body measures. The number of trials is not in the abstract.

Results

Lower triglycerides and CRP on average, but the huge differences between trials make the size of the effect very uncertain.

Effect sizes as reported

Triglycerides WMD -85.78 mg/dL (-155.24 to -16.32), I2 98%; CRP WMD -2.66 mg/L (-4.07 to -1.24), I2 92%.

Why this rating

Very low: very high heterogeneity, small trials likely, and only people on dialysis.

Form and dose studied

Flaxseed oil as studied; higher amounts (over 10 g a day) were linked to subgroup effects.

Who was studied

Adults on haemodialysis.

Limits

Applies only to dialysis patients, not to the general public. Number of trials and people not in the abstract.

Why researchers looked

People with kidney failure often have high blood fats and inflammation.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Not established

Not established.

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

People with kidney disease must ask their kidney team before any supplement.

¹⁵

Skin sensitivity and dryness

Very low certainty

A small 12-week trial in 26 women with sensitive skin reported less skin sensitivity, roughness and scaling and better hydration with flaxseed oil taken by mouth. Safflower oil gave a smaller effect. It is a single very small trial.

1 studiesFlaxseed oil taken by mouth for 12 weeks; amount not given in the abs…

Studies, doses and limits

What the trials found

The randomised double-blind 12-week trial gave women with sensitive skin (13 per group) flaxseed oil or safflower seed oil. Flaxseed oil was followed by lower sensitivity after a skin irritation test, lower water loss through the skin, less roughness and scaling, and higher smoothness and hydration. Safflower oil improved roughness and hydration later and less. The abstract gives no numbers.

Results

A positive result in one very small trial without numbers. No other human trial of oral flaxseed oil for skin was read.

Effect sizes as reported

No effect sizes in the abstract.

Why this rating

Very low: one trial of 26 people, no numbers in the abstract, no placebo oil comparison.

Form and dose studied

Flaxseed oil taken by mouth for 12 weeks; amount not given in the abstract.

Who was studied

Women with sensitive skin.

Limits

Single small trial; compared with another oil, not a neutral placebo.

Why researchers looked

Omega-3 fats are part of skin cell membranes, so oils have been tested for skin condition.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Preliminary mechanism

Not established; the plasma omega-6 to omega-3 ratio fell in the flaxseed group in this trial.

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

None specific.

¹²

ADHD symptoms in children

Very low certainty

A small 8-week trial in 40 children with ADHD found no difference between oil with ALA and placebo. Only 17 children finished, so the trial could not settle the question.

1 studiesOil with 1 g ALA in a 2 g daily portion, for 8 weeks, as studied in t…

Studies, doses and limits

What the trials found

The double-blind trial randomised 40 untreated children aged 6 to 16 to 2 g a day of oil containing 1 g ALA or placebo for 8 weeks. Seventeen (42.5%) finished. No significant difference was found in any measure, from doctor, computer test, parent or teacher reports. Dropouts cited capsule size, poor compliance and no sense of effect.

Results

No benefit found, but the trial was too small and lost most of its children to dropout.

Effect sizes as reported

No significant between-group difference in any ADHD measure.

Why this rating

Very low: tiny trial with 58% dropout. It neither shows a benefit nor rules one out.

Form and dose studied

Oil with 1 g ALA in a 2 g daily portion, for 8 weeks, as studied in the trial.

Who was studied

Children aged 6 to 16 with ADHD, not on medicines.

Limits

ADHD should be assessed and treated by a doctor. Not advice to give children oil.

Why researchers looked

Omega-3 fats have been tried for attention problems, mostly fish-type omega-3s.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Not established

Not established.

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

Do not give supplements to children without asking a doctor.

⁵

Thinking and memory

Not enough evidence

A 2022 review says the role of ALA in thinking is at an early stage but shows promising evidence of counteracting cognitive impairment. No trial of flaxseed oil alone for memory was read.

2 studiesALA from walnuts and flaxseed in the studies reviewed.

Studies, doses and limits

What the trials found

The 2022 narrative review summarises early work on ALA and cognition and calls the evidence promising but at an early stage. The abstract gives no trial numbers. The NCCIH omega-3 page (November 2024) describes evidence for other omega-3 uses in depression, ADHD, Alzheimer's and dry eye as uncertain or inconsistent, mostly for fish-type products.

Results

Too early to say. The only source read is a review abstract with no numbers.

Effect sizes as reported

No effect sizes in the sources read.

Why this rating

Insufficient: the sources read are a narrative review abstract and a general NCCIH statement about omega-3 supplements.

Form and dose studied

ALA from walnuts and flaxseed in the studies reviewed.

Who was studied

Older adults in the studies reviewed.

Limits

No trial read was of flaxseed oil alone.

Why researchers looked

Researchers ask whether ALA-rich foods such as walnuts help the ageing brain.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Not established

Not established.

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

None specific.

^{13 21}

Prostate cancer and cancer deaths

Very low certainty

Some early studies suggested ALA might raise prostate cancer risk. A 2013 review of 12 studies found no clear link, and a 2021 review of cohorts found a slightly higher risk of cancer death with higher ALA intake (RR 1.06). The evidence is mixed and observational.

2 studiesDietary ALA intake (observed), not supplements.

Studies, doses and limits

What the trials found

A 2013 meta-analysis (5 prospective and 7 case-control studies) found ALA intake positively but not significantly linked to prostate cancer (RR 1.08, 0.90 to 1.29; I2 85%); removing one study made the prospective studies show a small protective link (RR 0.91, 0.83 to 0.99). A 2021 BMJ meta-analysis of cohorts found a slightly higher risk of cancer death with high ALA intake (RR 1.06, 1.02 to 1.11).

Results

No clear link to prostate cancer; a small rise in cancer deaths in one large observational review. Observational only.

Effect sizes as reported

Prostate cancer RR 1.08 (0.90 to 1.29); cancer deaths RR 1.06 (1.02 to 1.11).

Why this rating

Very low: observational, large differences between studies, and the two reviews do not agree on direction.

Form and dose studied

Dietary ALA intake (observed), not supplements.

Who was studied

Men in prostate cancer studies; adults in mortality cohorts.

Limits

Cannot show cause. The prostate result depended on dropping one study.

Why researchers looked

Observational studies raised a question about ALA and prostate cancer, so researchers pooled them.

Traditional use

Flaxseed has a long history of traditional use (NCCIH). Flaxseed oil is sold as a source of the plant omega-3 fat ALA. Being a source of ALA is different from showing that the oil treats a condition.

Proposed mechanism Not established

No mechanism was established in the sources read.

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

Men with prostate cancer or a family history should ask their doctor before supplements.

^{4 11}

Connections to the rest of health

How Flaxseed Oil and Plant Omega-3 (ALA) 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
Balanced Nutrition	High certainty	Essential omega-3 fat (ALA) and how much is eaten: ALA (alpha-linolenic acid) is an omega-3 fat the body cannot make, so it has to come from food. The US National Academy of Medicine sets an adequate intake of 1.6 g a day for men and 1.1 g a day for women aged 19 and over. Flaxseed oil is the richest plant source of ALA.	^{18 19}
Heart Health	High certainty	Essential omega-3 fat (ALA) and how much is eaten: ALA (alpha-linolenic acid) is an omega-3 fat the body cannot make, so it has to come from food. The US National Academy of Medicine sets an adequate intake of 1.6 g a day for men and 1.1 g a day for women aged 19 and over. Flaxseed oil is the richest plant source of ALA.	^{18 19}
Balanced Nutrition	High certainty	Food sources of plant omega-3 (ALA): Per USDA data, one tablespoon of flaxseed oil has about 7.3 g of ALA. An ounce of dried chia seeds has about 5.1 g, an ounce of English walnuts about 2.6 g (total 18:3 fat), a tablespoon of ground flaxseed about 1.6 g, a tablespoon of walnut oil about 1.4 g, canola oil about 1.3 g and soybean oil about 0.9 g.	^{23 18 19}
Heart Health	High certainty	Food sources of plant omega-3 (ALA): Per USDA data, one tablespoon of flaxseed oil has about 7.3 g of ALA. An ounce of dried chia seeds has about 5.1 g, an ounce of English walnuts about 2.6 g (total 18:3 fat), a tablespoon of ground flaxseed about 1.6 g, a tablespoon of walnut oil about 1.4 g, canola oil about 1.3 g and soybean oil about 0.9 g.	^{23 18 19}
Heart Health	Moderate certainty	Making fish-type omega-3s (EPA and DHA) from ALA: The body can turn some ALA into the longer omega-3 fats EPA and DHA, but not much. Reviews say ALA raises blood EPA a little, has little effect on blood DHA, and that only DHA taken ready-made reliably raises blood DHA. Women convert more than men.	^{2 3 18}
Brain Health	Moderate certainty	Making fish-type omega-3s (EPA and DHA) from ALA: The body can turn some ALA into the longer omega-3 fats EPA and DHA, but not much. Reviews say ALA raises blood EPA a little, has little effect on blood DHA, and that only DHA taken ready-made reliably raises blood DHA. Women convert more than men.	^{2 3 18}
Heart Health	Low certainty	Heart and blood vessel events: Large reviews find that eating more ALA probably makes little or no difference to deaths. It may slightly lower cardiovascular events (low certainty) and probably slightly lowers irregular heartbeat (moderate certainty, from only 2 trials). In the biggest ALA trial, in people who had had a heart attack, ALA margarine did not significantly reduce events. Blood pressure and blood fats: A 2023 review of 19 trials in people with overweight or obesity found plant ALA lowered systolic blood pressure, triglycerides, CRP and TNF-alpha slightly, but raised LDL cholesterol slightly. A 2024 review that included only 3 flaxseed oil trials found no change in blood pressure.	^{1 9 13 19 16 10 14}
Heart Health	Low certainty	Deaths in long-term observational studies: In 41 follow-up studies of over a million adults, people who ate more ALA had a lower risk of dying from any cause (10% lower), from cardiovascular disease and from coronary heart disease. These studies cannot show that ALA caused the difference.	¹¹
Healthy Aging	Low certainty	Deaths in long-term observational studies: In 41 follow-up studies of over a million adults, people who ate more ALA had a lower risk of dying from any cause (10% lower), from cardiovascular disease and from coronary heart disease. These studies cannot show that ALA caused the difference.	¹¹
Cholesterol Balance	Low certainty	Blood pressure and blood fats: A 2023 review of 19 trials in people with overweight or obesity found plant ALA lowered systolic blood pressure, triglycerides, CRP and TNF-alpha slightly, but raised LDL cholesterol slightly. A 2024 review that included only 3 flaxseed oil trials found no change in blood pressure.	^{16 10 1}
Inflammation Balance	Mixed findings	Inflammation markers (CRP, TNF, IL-6): A 25-trial review found no benefit of dietary ALA on inflammation markers, and healthy people might even see CRP rise. A smaller 2023 review in people with overweight found lower CRP and TNF-alpha. Results are mixed.	^{14 16 10}
Blood Sugar Balance	Low certainty	Blood sugar in type 2 diabetes: A 2017 review of 8 small trials found ALA-enriched diets did not change HbA1c, fasting glucose or fasting insulin. The authors say there are too few trials to be sure and that higher intakes may work differently.	^{8 20}
Metabolic Health	Low certainty	Blood sugar in type 2 diabetes: A 2017 review of 8 small trials found ALA-enriched diets did not change HbA1c, fasting glucose or fasting insulin. The authors say there are too few trials to be sure and that higher intakes may work differently.	^{8 20}
Blood Sugar Balance	Very low certainty	Blood sugar in gestational diabetes: One small 6-week trial in 60 women with gestational diabetes reported lower fasting glucose, insulin resistance and triglycerides with flaxseed oil capsules. The journal has since published an expression of concern about this paper, so it should be treated cautiously. NCCIH says research is limited.	^{6 7 20}
Womens Wellness	Very low certainty	Blood sugar in gestational diabetes: One small 6-week trial in 60 women with gestational diabetes reported lower fasting glucose, insulin resistance and triglycerides with flaxseed oil capsules. The journal has since published an expression of concern about this paper, so it should be treated cautiously. NCCIH says research is limited.	^{6 7 20}
Heart Health	Very low certainty	Blood fats and CRP in people on dialysis: A 2024 review reported lower triglycerides and CRP with flaxseed oil in people having haemodialysis, but results differed hugely between trials (I2 above 90%).	¹⁵
Inflammation Balance	Very low certainty	Blood fats and CRP in people on dialysis: A 2024 review reported lower triglycerides and CRP with flaxseed oil in people having haemodialysis, but results differed hugely between trials (I2 above 90%).	¹⁵
Skin Hair Beauty	Very low certainty	Skin sensitivity and dryness: A small 12-week trial in 26 women with sensitive skin reported less skin sensitivity, roughness and scaling and better hydration with flaxseed oil taken by mouth. Safflower oil gave a smaller effect. It is a single very small trial.	¹²
Focus Memory	Very low certainty	ADHD symptoms in children: A small 8-week trial in 40 children with ADHD found no difference between oil with ALA and placebo. Only 17 children finished, so the trial could not settle the question.	⁵
Brain Health	Very low certainty	ADHD symptoms in children: A small 8-week trial in 40 children with ADHD found no difference between oil with ALA and placebo. Only 17 children finished, so the trial could not settle the question.	⁵
Memory Support	Not enough evidence	Thinking and memory: A 2022 review says the role of ALA in thinking is at an early stage but shows promising evidence of counteracting cognitive impairment. No trial of flaxseed oil alone for memory was read.	^{13 21}
Brain Health	Not enough evidence	Thinking and memory: A 2022 review says the role of ALA in thinking is at an early stage but shows promising evidence of counteracting cognitive impairment. No trial of flaxseed oil alone for memory was read.	^{13 21}
Preventive Wellness	Very low certainty	Prostate cancer and cancer deaths: Some early studies suggested ALA might raise prostate cancer risk. A 2013 review of 12 studies found no clear link, and a 2021 review of cohorts found a slightly higher risk of cancer death with higher ALA intake (RR 1.06). The evidence is mixed and observational.	^{4 11}
Mens Vitality	Very low certainty	Prostate cancer and cancer deaths: Some early studies suggested ALA might raise prostate cancer risk. A 2013 review of 12 studies found no clear link, and a 2021 review of cohorts found a slightly higher risk of cancer death with higher ALA intake (RR 1.06). The evidence is mixed and observational.	^{4 11}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Nutrition	Biological association	High certainty	Studied for: Essential omega-3 fat (ALA) and how much is eaten Studied for: Food sources of plant omega-3 (ALA)	^{18 19 23}
Whole Body	Biological association	High certainty	Studied for: Essential omega-3 fat (ALA) and how much is eaten Studied for: Making fish-type omega-3s (EPA and DHA) from ALA	^{18 19 2 3 11 14 16 10 15 4}
Digestive System	Biological association	High certainty	Studied for: Food sources of plant omega-3 (ALA)	^{23 18 19}
Cardiovascular System	Biological association	Moderate certainty	Studied for: Making fish-type omega-3s (EPA and DHA) from ALA Studied for: Heart and blood vessel events	^{2 3 18 1 9 13 19 11 16 10 14 15}
Heart Circulation	Biological association	Low certainty	Studied for: Heart and blood vessel events Studied for: Blood pressure and blood fats	^{1 9 13 19 16 10}
Blood Sugar Support	Biological association	Low certainty	Studied for: Blood sugar in type 2 diabetes Studied for: Blood sugar in gestational diabetes	^{8 20 6 7}
Endocrine System	Biological association	Low certainty	Studied for: Blood sugar in type 2 diabetes	^{8 20}
Reproductive Health	Biological association	Very low certainty	Studied for: Blood sugar in gestational diabetes	^{6 7 20}
Skin	Biological association	Very low certainty	Studied for: Skin sensitivity and dryness	¹²
Brain Focus	Biological association	Very low certainty	Studied for: ADHD symptoms in children Studied for: Thinking and memory	^{5 13 21}
Nervous System	Biological association	Very low certainty	Studied for: ADHD symptoms in children Studied for: Thinking and memory	^{5 13 21}
Reproductive System	Biological association	Very low certainty	Studied for: Prostate cancer and cancer deaths	^{4 11}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Flaxseed allergy	Adverse effect or risk	Reported reactions	Allergic and anaphylactic reactions have been reported. Preparation or compound: Flaxseed oil	¹⁸

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Blood EPA and DHA levels	Biological association	Moderate certainty	Measured in trials: EPA higher, DHA little changed. A lab change is not the same as a health benefit.	^{2 3 18}
Systolic blood pressure	Biological association	Low certainty	Measured in trials: slightly lower in one review; no change in another. A lab change is not the same as a health benefit.	^{16 10}
Triglycerides and LDL cholesterol	Biological association	Low certainty	Measured in trials: triglycerides lower; LDL slightly higher. A lab change is not the same as a health benefit.	^{16 1}
C-reactive protein (CRP)	Biological association	Mixed findings	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{14 16 15}
HbA1c and fasting glucose	Biological association	Low certainty	Measured in trials: no clear change. A lab change is not the same as a health benefit.	⁸
Water loss through the skin (TEWL)	Biological association	Very low certainty	Measured in trials: lower (one small trial). A lab change is not the same as a health benefit.	¹²

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
EPA and DHA	Preliminary mechanism	Human	ALA is a precursor but converts poorly to DHA.	^{2 3}
Linoleic acid (omega-6)	Preliminary mechanism	Human	The other essential fat; flaxseed oil carries about a quarter as much as ALA.	²³

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Alpha-linolenic acid (ALA)	Biological association	Human	Essential fat; starting material for EPA and DPA in the body. Preparation or compound: Seed oil	^{23 2}
Linoleic acid (LA)	Biological association	Human	Essential omega-6 fat that sits alongside ALA in the oil; its role was not examined further in the sources read. Preparation or compound: Seed oil	²³
Eicosapentaenoic acid (EPA)	Biological association	Human	Made in small amounts from ALA. Preparation or compound: Not present in flaxseed oil	^{3 2}
Docosahexaenoic acid (DHA)	Biological association	Human	Made in very small amounts from ALA. Preparation or compound: Not present in flaxseed oil	^{3 2}

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 26, 2026).

Evidence at a glance: what changed in 1 lab markers

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

Inflammatory1

The evidence

The research centre for Flaxseed Oil and Plant Omega-3 (ALA). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Essential omega-3 fat (ALA) and how much is eaten 2 studies High certainty Food sources of plant omega-3 (ALA) 3 studies High certainty Making fish-type omega-3s (EPA and DHA) from ALA 3 studies Moderate certainty Heart and blood vessel events 4 studies Low certainty Deaths in long-term observational studies 1 study Low certainty Blood pressure and blood fats 3 studies Low certainty Inflammation markers (CRP, TNF, IL-6) 3 studies Mixed findings Blood sugar in type 2 diabetes 2 studies Low certainty Blood sugar in gestational diabetes 3 studies Very low certainty Blood fats and CRP in people on dialysis 1 study Very low certainty Skin sensitivity and dryness 1 study Very low certainty ADHD symptoms in children 1 study Very low certainty Thinking and memory 2 studies Not enough evidence Prostate cancer and cancer deaths 2 studies Very low certainty

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 started from our existing ALA summary, read NCCIH, MedlinePlus and Linus Pauling Institute pages, re-checked food values in saved USDA FoodData Central data, and re-read PubMed abstracts for reviews and trials. Only abstracts were read for studies. The NIH Office of Dietary Supplements pages were blocked and are marked unread.

Study library: every study we checked 23

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Abdelhamid 2020 Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev · PMID 32114706 · DOI	Systematic review meta analysis	162796 Adults at varying cardiovascular risk in 86 trials lasting 12 to 88 months; 5 trials tested plant omega-3 (ALA), 19,327 people	Increased ALA (from supplements, enriched foods or advice) or increased fish omega-3 (EPA/DHA) Mixed (ALA trials used enriched foods and supplements) 12 to 88 months · vs Usual or lower intake	For ALA: probably little or no effect on deaths. Cardiovascular events may be slightly lower (low certainty), and irregular heartbeat probably slightly lower (moderate certainty, 2 trials). Stroke effects unclear. ALA, all-cause deaths RR 1.01; heart deaths RR 0.96; coronary heart disease events RR 1.00 (low certainty); cardiovascular events RR 0.95 (RR 0.91 in low-bias trials); arrhythmia RR 0.73 (All-cause deaths 0.84 to 1.20; heart deaths 0.74 to 1.25; CHD events 0.82 to 1.22; cardiovascular events 0.83 to 1.07 (0.79 to 1.04 in low-bias trials); arrhythmia 0.55 to 0.97) Methods, limits and funding Outcomes: All-cause and heart deaths, cardiovascular events, arrhythmia, stroke, lipids, blood pressure Limitations: Only 5 trials tested ALA and they mostly used enriched foods such as margarine, not flaxseed oil alone. The cardiovascular events result includes no effect in its range. Funding and conflicts: Review authors report no conflicts of interest (abstract). Registration: Cochrane review Read: abstract
Brenna 2009 alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids · PMID 19269799 · DOI	Narrative review	Review of human studies in healthy adults and infants	Supplemental ALA Plant oils · vs Preformed DHA or none	ALA raises blood EPA and DPA but has little effect on DHA. Only preformed DHA reliably raises blood DHA. No numbers in the abstract (Not applicable) Methods, limits and funding Outcomes: Blood levels of EPA, DPA and DHA after ALA Limitations: A narrative review by a society working group, read from the abstract only. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Burdge 2005 Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reprod Nutr Dev · PMID 16188209 · DOI	Narrative review	Review of tracer and feeding studies in adults	Dietary ALA Plant oils Weeks to months in the studies reviewed	Conversion to EPA is limited in men and to DHA is very low. Women convert more. No numbers in the abstract (Not applicable) Methods, limits and funding Outcomes: Conversion of ALA to EPA and DHA Limitations: A 2005 narrative review, read from the abstract only. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Carleton 2013 Case-control and prospective studies of dietary alpha-linolenic acid intake and prostate cancer risk: a meta-analysis. BMJ Open · PMID 23674441 · DOI	Systematic review meta analysis observational	5 prospective and 7 case-control studies in men	Higher versus lower dietary ALA intake (observed) Diet · vs Lowest intake group	No clear link overall. Removing one study made the prospective studies show a small protective link. All studies RR 1.08 (P=0.40, I2 85%); prospective studies after removing one study RR 0.91 (All 0.90 to 1.29; prospective 0.83 to 0.99) Methods, limits and funding Outcomes: Prostate cancer risk Limitations: Observational, large differences between studies. The protective result depended on removing a study. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Dubnov-Raz 2014 The effect of alpha-linolenic acid supplementation on ADHD symptoms in children: a randomized controlled double-blind study. Front Hum Neurosci · PMID 25339885 · DOI	Randomised controlled trial	40 40 untreated children aged 6 to 16 with ADHD; only 17 finished	Oil with ALA Plant oil 2 g oil a day containing 1 g ALA 8 weeks · vs Placebo	No significant difference in any measure between ALA and placebo. No between-group difference in the change in any ADHD measure (Not given in the abstract) Methods, limits and funding Outcomes: ADHD symptoms by doctor, tests, parent and teacher questionnaires Limitations: Small trial; 58% dropped out (capsule size, poor compliance, no sense of effect). Too small to rule out a benefit. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Jamilian 2020 The effects of n-3 fatty acids from flaxseed oil on genetic and metabolic profiles in patients with gestational diabetes mellitus: a randomised, double-blind, placebo-controlled trial. Br J Nutr · PMID 31902378 · DOI	Randomised controlled trial	60 60 women with gestational diabetes	Flaxseed-oil capsules (each with 400 mg ALA) Flaxseed oil 2 capsules a day 6 weeks · vs Placebo	The abstract reports lower fasting glucose, insulin and insulin resistance, lower triglycerides and CRP, compared with placebo. The journal later added an expression of concern about this paper. Fasting glucose P=0.001; insulin resistance P<0.001; triglycerides P<0.001; CRP P=0.006 (no effect sizes in the abstract) (Not given in the abstract) Methods, limits and funding Outcomes: Fasting glucose, insulin, insulin resistance, blood fats, inflammation markers, gene activity Limitations: Small trial of 6 weeks. Expression of concern published by the journal in January 2022 (see the separate notice). Effect sizes are not in the abstract. Lab markers only. Funding and conflicts: Funding is not stated in the abstract. A journal expression of concern applies to this paper. Registration: Not stated in the abstract Read: abstract
Jamilian 2022 The effects of omega-3 fatty acids from flaxseed oil on genetic and metabolic profiles in patients with gestational diabetes mellitus: a randomized, double-blind, placebo-controlled trial - Expression of concern. Br J Nutr · PMID 34689847 · DOI	Journal notice n/a	Notice about the 2020 gestational diabetes trial (PMID 31902378)	Not applicable	The journal published an expression of concern about the 2020 trial. The notice text in PubMed does not give the reason. Not applicable (Not applicable) Methods, limits and funding Outcomes: Not applicable Limitations: Only the notice record was read, not the reason for the concern. Not a retraction. Funding and conflicts: Not applicable Read: abstract
Jovanovski 2017 The effect of alpha-linolenic acid on glycemic control in individuals with type 2 diabetes: A systematic review and meta-analysis of randomized controlled clinical trials. Medicine (Baltimore) · PMID 28538363 · DOI	Systematic review meta analysis	212 People with type 2 diabetes; 8 trials of one month or longer	ALA-enriched diets Plant ALA sources Median 4.4 g a day ALA (HbA1c trials), 5.4 g a day (glucose trials) Median 3 months · vs Usual diet	No effect on HbA1c, fasting glucose or fasting insulin. After a statistical adjustment for missing small studies, a small HbA1c fall appeared. The authors say firm conclusions are not possible. HbA1c MD -0.01% (P=0.96); fasting glucose MD 0.07; fasting insulin MD 7.03 (all not significant) (HbA1c -0.32 to 0.31; glucose -0.61 to 0.76; insulin -5.84 to 19.89) Methods, limits and funding Outcomes: HbA1c, fasting glucose, fasting insulin Limitations: Only 8 small trials, large unexplained differences between them (I2 75% or more). Funding and conflicts: Several authors disclose past research funding from food-industry groups and public bodies; none is tied to this review in the abstract. Read: abstract
Kromhout 2010 n-3 fatty acids and cardiovascular events after myocardial infarction. N Engl J Med · PMID 20929341 · DOI	Randomised controlled trial	4837 Patients aged 60 to 80 (78% men) who had had a heart attack and were on modern heart medicines	Margarine with ALA added (targeted extra 2 g ALA a day; actual about 1.9 g), or with EPA+DHA, or both, or placebo margarine Plant-oil margarine About 1.9 g ALA a day achieved 40 months · vs Placebo margarine	ALA did not significantly cut major cardiovascular events. In the pre-planned subgroup of women the result approached significance but did not reach it. ALA versus placebo: hazard ratio 0.91 (P=0.20). Women: hazard ratio 0.73 (P=0.07). Adverse events did not differ between groups. (ALA 0.78 to 1.05; women 0.51 to 1.03) Methods, limits and funding Outcomes: Major cardiovascular events (fatal and non-fatal events and cardiac procedures) Limitations: A margarine, not flaxseed oil. Low extra ALA intake. People already on strong heart treatment. The women result was a subgroup and not significant. Funding and conflicts: Funded by the Netherlands Heart Foundation and others (per abstract). Registration: ClinicalTrials.gov NCT00127452 Read: abstract
McNabb 2024 Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults: A Systematic Literature Review and Meta-Analysis. Curr Hypertens Rev · PMID 39558500 · DOI	Systematic review meta analysis	Healthy adults and adults at risk of high blood pressure; 17 trials, of which only 3 tested flaxseed oil (14 tested olive oil)	Olive oil or flaxseed oil supplementation Flaxseed oil (3 trials) and olive oil (14 trials) · vs Control	No significant effect on blood pressure or on CRP or IL-6. Only 3 of 17 trials used flaxseed oil. Systolic BP mean difference -0.48 mmHg; diastolic -0.47 mmHg; CRP 0.11; IL-6 -0.15 (all not significant) (Systolic -1.76 to 0.80; diastolic -1.33 to 0.39; CRP -1.18 to 0.40; IL-6 -0.57 to 0.27) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure; CRP, IL-6, TNF-alpha Limitations: The result is mostly about olive oil; flaxseed oil was a small part. The abstract reports a TNF-alpha interval below zero next to a P value that is not significant, so that line is unclear. Funding and conflicts: Authors declare no conflict of interest. Read: abstract
Naghshi 2021 Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of cohort studies. BMJ · PMID 34645650 · DOI	Systematic review meta analysis cohorts	1197564 41 prospective cohort studies in adults, followed 2 to 32 years; 198,113 deaths	Higher versus lower dietary ALA intake or blood ALA (observed, not assigned) Diet (mostly walnuts, canola and other plant oils) 2 to 32 years follow-up · vs Lowest versus highest intake group	Higher ALA intake went with fewer deaths from any cause, cardiovascular disease and coronary heart disease, but slightly more cancer deaths. All-cause RR 0.90; cardiovascular RR 0.92; coronary heart disease RR 0.89; cancer deaths RR 1.06. Each extra 1 g a day of ALA: all-cause RR 0.95 (All-cause 0.83 to 0.97 (I2 78%); cardiovascular 0.86 to 0.99; CHD 0.81 to 0.97; cancer 1.02 to 1.11; per 1 g/day 0.91 to 0.99) Methods, limits and funding Outcomes: Deaths from any cause, cardiovascular disease, coronary heart disease and cancer Limitations: Observational: cannot show cause. People who eat more ALA may differ in other habits. Large differences between studies (I2 78% for all-cause deaths). Funding and conflicts: Authors report no relevant financial relationships (abstract). Registration: PROSPERO CRD42021229487 Read: abstract
Neukam 2011 Supplementation of flaxseed oil diminishes skin sensitivity and improves skin barrier function and condition. Skin Pharmacol Physiol · PMID 21088453 · DOI	Randomised controlled trial	26 26 women with sensitive skin (13 per group)	Flaxseed oil taken by mouth Flaxseed oil 12 weeks · vs Safflower seed oil	With flaxseed oil, skin sensitivity, water loss, roughness and scaling fell and hydration rose. Safflower oil gave a smaller change. Effect sizes not in the abstract (Not given in the abstract) Methods, limits and funding Outcomes: Skin sensitivity, water loss through skin, roughness, scaling, hydration Limitations: Very small trial of 13 women per group, compared with another oil rather than placebo, and the abstract does not show numbers. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Sala-Vila 2022 Impact of alpha-Linolenic Acid, the Vegetable omega-3 Fatty Acid, on Cardiovascular Disease and Cognition. Adv Nutr · PMID 35170723 · DOI	Narrative review with meta analysis summary	Review of observational studies and trials on ALA, heart disease, diabetes and thinking	Dietary ALA (mainly walnuts and flaxseed) Walnuts, flaxseed	Observational studies link more ALA to less heart disease. Three trials of ALA-rich diets showed benefit but the one designed for ALA alone only showed a trend. For metabolic syndrome and obesity the evidence is inconclusive. Cognition research is at an early stage. Observational meta-analyses: about 10% lower total cardiovascular disease and 20% lower fatal coronary heart disease (Not given in the abstract) Methods, limits and funding Outcomes: Cardiovascular disease, blood fats, blood pressure, inflammation, diabetes risk, cognition Limitations: A review by researchers who study nuts and plant fats, read from the abstract only. It mixes observational and trial evidence. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Su 2018 Effect of dietary alpha-linolenic acid on blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Eur J Nutr · PMID 28275869 · DOI	Systematic review meta analysis	Adults; 25 randomised trials	Increased dietary ALA (foods and supplements) Plant sources · vs Control diet	No benefit on any inflammatory marker. In healthy people ALA might raise CRP. TNF SMD -0.03; IL-6 -0.17; CRP -0.06; sICAM-1 -0.06; sVCAM-1 -0.24 (all not significant) (TNF -0.36 to 0.29; IL-6 -0.46 to 0.12; CRP -0.24 to 0.12; sICAM-1 -0.26 to 0.13; sVCAM-1 -0.56 to 0.09) Methods, limits and funding Outcomes: TNF, IL-6, CRP, sICAM-1, sVCAM-1 Limitations: Mixed foods and supplements, not flaxseed oil alone. Marker levels are not the same as illness. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Tabrizi 2024 The impact of flaxseed oil on lipid profiles, weight loss, and inflammatory markers in hemodialysis patients: A systematic review and meta-analysis of randomized controlled trials. Ther Apher Dial · PMID 38726572 · DOI	Systematic review meta analysis	People having haemodialysis (kidney failure); number of trials not given in the abstract	Flaxseed oil Flaxseed oil Subgroup effects were seen above 10 g a day · vs Control	Lower triglycerides and CRP with flaxseed oil, but results differed hugely between trials. No effect on body measures. Triglycerides WMD -85.78 mg/dL (I2 98%); CRP WMD -2.66 mg/L (I2 92%) (Triglycerides -155.24 to -16.32; CRP -4.07 to -1.24) Methods, limits and funding Outcomes: Triglycerides, CRP, other blood fats, body measures Limitations: Very high heterogeneity (I2 above 90%). Only people on dialysis. Small trials are likely. Number of trials and people not in the abstract. Funding and conflicts: Funding is not stated in the abstract. Registration: PROSPERO CRD42023484076 Read: abstract
Yin 2023 Effect of Alpha-Linolenic Acid Supplementation on Cardiovascular Disease Risk Profile in Individuals with Obesity or Overweight: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Adv Nutr · PMID 37778442 · DOI	Systematic review meta analysis	1183 Adults with overweight or obesity; 19 randomised trials	Plant ALA by oral supplement, food or both (flaxseed and flaxseed oil in the subgroup that did best) Flaxseed, flaxseed oil and other plant sources Subgroup that did best: 3 g ALA a day or more Subgroup that did best: 12 weeks or longer · vs Placebo	Lower CRP, TNF-alpha, triglycerides and systolic blood pressure, but slightly higher LDL cholesterol. No clear effect on IL-6, diastolic pressure, total or HDL cholesterol. CRP SMD -0.38; TNF-alpha SMD -0.45; triglycerides SMD -4.41; systolic BP SMD -0.37; LDL SMD +1.32 (units as printed in the abstract) (CRP -0.72 to -0.04; TNF-alpha -0.73 to -0.17; triglycerides -5.99 to -2.82; systolic BP -0.66 to -0.08; LDL 0.05 to 2.59) Methods, limits and funding Outcomes: C-reactive protein, TNF-alpha, triglycerides, blood pressure, LDL and other cholesterol Limitations: Only people with overweight or obesity. Mixed sources, not flaxseed oil alone. The units printed for the pooled effects are unusual, so the size of each effect is hard to judge from the abstract. Funding and conflicts: Funding is not stated in the abstract. Registration: PROSPERO CRD42023429563 Read: abstract
s-gbif-linum GBIF Backbone Taxonomy: Linum usitatissimum L. (usageKey 2873861, status ACCEPTED, family Linaceae) · Source	Database record n/a			Methods, limits and funding Read: full-text
s-lpi-efa Linus Pauling Institute, Oregon State University: Essential Fatty Acids (page updated May 2019, reviewed June 2019) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-medlineplus-omega3 MedlinePlus: Omega-3 fats - Good for your heart (review date 2026-04-30) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-nccih-flaxseed NCCIH (US National Institutes of Health): Flaxseed and Flaxseed Oil (page shows last updated February 2025) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-nccih-omega3 NCCIH (US National Institutes of Health): Omega-3 Supplements: What You Need To Know (page shows last updated November 2024) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-ods-omega3 NIH Office of Dietary Supplements: Omega-3 Fatty Acids fact sheets · Source	Reference database n/a			Methods, limits and funding Read: not-read
s-usda-sr-legacy-ala USDA FoodData Central, SR Legacy (April 2018 release): fatty acids in flaxseed oil, flaxseed, chia seeds, walnuts, canola, soybean and walnut oil · Source	Nutrient database n/a			Methods, limits and funding Read: full-text

What we do not know yet

No large trial of flaxseed oil alone was read for heart attacks, strokes or blood pressure.
The NIH Office of Dietary Supplements fact sheets could not be read (blocked), so any official upper limit is not stated.
Food ALA and flaxseed oil pills were not compared in trials.
No source was read on contaminants or label accuracy of flaxseed oil supplements.
Pregnancy, breastfeeding and children safety is described only in general terms.
The reason for the journal's concern about the gestational diabetes trial was not found.

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".

Inflammatory 1

↕

C-reactive protein (CRP)

Mixed results in trials

A blood marker that rises with inflammation.

Mixed findings

Results and what it means

Why it was measured

To see whether plant ALA lowers general inflammation.

Statistical vs. clinical meaning

Reviews disagree; a marker change is not a health outcome.

Safety implication

None specific.

Study	Result	People	Product
¹⁴	No significant change (SMD -0.06, -0.24 to 0.12); healthy subjects might see a rise	25 trials in adults	Dietary ALA
¹⁶	Lower CRP (SMD -0.38, -0.72 to -0.04)	19 trials in adults with overweight or obesity	Plant ALA, flaxseed and flaxseed oil included
¹⁵	Lower CRP (WMD -2.66 mg/L, -4.07 to -1.24; I2 92%)	Haemodialysis patients	Flaxseed oil

^{14 16 15}

Other 5

●

Blood EPA and DHA levels

EPA higher, DHA little changed in trials

The amounts of the omega-3 fats EPA and DHA found in blood or blood cells. They show recent intake.

Moderate certainty

Results and what it means

Why it was measured

To see whether plant ALA raises the fish-type omega-3s the body uses.

Statistical vs. clinical meaning

A blood-marker change; it does not show a health benefit.

Safety implication

None specific.

Study	Result	People	Product
²	ALA supplements raise blood EPA and DPA but have little effect on DHA; preformed DHA is needed to raise DHA	Healthy adults and infants (review)	Supplemental ALA from plant oils

^{2 3 18}

●

Systolic blood pressure

Slightly lower in one review; no change in another in trials

The top blood pressure number, measured when the heart beats.

Low certainty

Results and what it means

Why it was measured

To see whether plant omega-3 changes blood pressure.

Statistical vs. clinical meaning

Small and inconsistent between reviews.

Safety implication

People on blood pressure medicine should not change treatment because of an oil.

Study	Result	People	Product
¹⁶	Lower systolic pressure (SMD -0.37, 95% CI -0.66 to -0.08)	19 trials in adults with overweight or obesity	Plant ALA from flaxseed, flaxseed oil and other sources
¹⁰	No significant change (-0.48 mmHg, -1.76 to 0.80)	17 trials (3 with flaxseed oil), healthy and at-risk adults	Olive oil or flaxseed oil

^{16 10}

●

Triglycerides and LDL cholesterol

Triglycerides lower; LDL slightly higher in trials

Blood fats. High triglycerides and high LDL cholesterol are linked to heart disease.

Low certainty

Results and what it means

Why it was measured

To see whether plant ALA improves blood fats.

Statistical vs. clinical meaning

A mixed lab-marker picture: one fat improved, another got slightly worse.

Safety implication

A slight LDL rise is possible; people with high cholesterol should ask a doctor.

Study	Result	People	Product
¹⁶	Triglycerides lower (SMD -4.41, -5.99 to -2.82); LDL higher (SMD +1.32, 0.05 to 2.59); total and HDL cholesterol unchanged	19 trials in adults with overweight or obesity	Plant ALA from flaxseed, flaxseed oil and other sources
¹	Little or no effect of ALA on lipids	Trials in adults at varying heart risk	Increased ALA

^{16 1}

●

HbA1c and fasting glucose

No clear change in trials

HbA1c shows average blood sugar over about 3 months. Fasting glucose is blood sugar after not eating.

Low certainty

Results and what it means

Why it was measured

To see whether plant ALA changes blood sugar control.

Statistical vs. clinical meaning

No clear change; too few trials to be sure.

Safety implication

People on diabetes medicines should ask their doctor before adding supplements.

Study	Result	People	Product
⁸	HbA1c MD -0.01% (-0.32 to 0.31); fasting glucose MD 0.07 (-0.61 to 0.76)	8 trials, 212 people with type 2 diabetes	ALA-enriched diets, median 4.4 to 5.4 g ALA a day

⁸

●

Water loss through the skin (TEWL)

Lower (one small trial) in trials

How much water escapes through the skin surface. Higher values mean a weaker skin barrier.

Very low certainty

Results and what it means

Why it was measured

To see whether oral flaxseed oil improves the skin barrier.

Statistical vs. clinical meaning

From one very small trial with no numbers in the abstract.

Safety implication

None specific.

Study	Result	People	Product
¹²	Significant fall in water loss, roughness and scaling with flaxseed oil (numbers not in the abstract)	26 women with sensitive skin	Flaxseed oil by mouth for 12 weeks versus safflower oil

¹²

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

Blood thinners: ask a pharmacist or doctor first. NCCIH says flaxseed or flaxseed oil might interact with anticoagulant or antiplatelet drugs, and calls these concerns theoretical. The Linus Pauling Institute says high intakes may reduce platelet clumping, so caution is advised with anticoagulant medicines. No case report or trial of a bleeding problem from flaxseed oil was read. Authoritative guidance (theoretical) ^{20 18}
Allergy is possible. The Linus Pauling Institute says allergic and anaphylactic reactions have been reported with flaxseed and flaxseed oil. Stop and get urgent help for swelling of the face or throat, trouble breathing, or a spreading rash. Authoritative guidance ¹⁸
Pregnancy and breastfeeding: not enough is known. NCCIH says some studies suggest flaxseed may be possibly unsafe in pregnancy but the evidence is not conclusive, that little is known about flaxseed oil in pregnancy, and that little is known about breastfeeding. Ask a doctor or midwife before using it. Authoritative guidance ²⁰
The oil spoils easily. The Linus Pauling Institute says polyunsaturated fats go rancid (oxidise) more easily than saturated fats, and that antioxidants such as vitamin E slow this. Flaxseed oil is very high in the polyunsaturated fat ALA. Follow the storage line on the label and do not use oil that smells sharp, bitter or like paint. Authoritative guidance ¹⁸
It is not a replacement for fish or algae omega-3. Reviews say the body turns only a small share of ALA into EPA and very little into DHA. If someone uses flaxseed oil thinking it gives the same thing as fish oil, it does not. Narrative reviews ^{2 3}

Side effects 5

Effect	How often	Severity and recovery	Evidence
Bloating, fullness, loose stools or diarrhoea NCCIH says limited amounts may be safe in the short term (up to 6 months).	No frequency found. NCCIH says higher amounts may cause uncomfortable digestive symptoms; the Linus Pauling Institute says high amounts may cause loose stools or diarrhoea.	Usually mild Not stated in the sources read.	Authoritative guidance ^{20 18}
Slightly higher LDL cholesterol Other markers (triglycerides, blood pressure) moved the other way in the same review; the Cochrane review found little or no effect on lipids.	A 2023 review of 19 trials in people with overweight or obesity found LDL higher (SMD 1.32, 0.05 to 2.59).	Small average change in a lab marker Not studied.	Meta-analysis ¹⁶
Possible rise in CRP in healthy people A subgroup result, not a main finding.	A 2018 review of 25 trials found ALA might raise CRP in healthy subjects (subgroup finding; overall CRP SMD -0.06, -0.24 to 0.12).	Small lab-marker change of unclear meaning Not studied.	Meta analysis subgroup ¹⁴
Taste, bad breath, heartburn, nausea (omega-3 supplements in general) This NCCIH list is for omega-3 supplements as a group, mostly fish-type products; it was not specific to flaxseed oil.	NCCIH says side effects of omega-3 supplements are usually mild and can include unpleasant taste, bad breath, bad-smelling sweat, headache, heartburn, nausea or diarrhoea.	Usually mild Not stated.	Authoritative guidance ²¹
Serious adverse events in large trials These trials mostly used ALA-enriched foods and low amounts.	The Cochrane review found increasing ALA had little or no effect on serious adverse events. In the Alpha Omega trial, adverse event rates did not differ significantly between the ALA margarine group and placebo.	Not applicable Not applicable	Meta analysis and randomised trial ^{1 9}

Liver

No liver injury from flaxseed oil or ALA was found in the sources read.

How often. No frequency was found.

Monitoring. No agency monitoring advice was found.

This is a safety connection. It is not evidence that Flaxseed Oil and Plant Omega-3 (ALA) supports liver health.

Medicines and supplements 3

With	Why it matters	Importance	Evidence	What to do
Blood thinners (warfarin, other anticoagulants) and antiplatelet drugs (such as aspirin or clopidogrel) prescription	Possible reduction in platelet clumping at high intakes (Linus Pauling Institute). Theoretical.	NCCIH says flaxseed or flaxseed oil might interact with these drugs; the concern is theoretical. No bleeding case report was found in the sources read.	Authoritative guidance (theoretical) Very low certainty ^{20 18}	Tell your doctor or pharmacist before use, especially before surgery or if you bruise or bleed easily.
Medicines for blood pressure, cholesterol or blood sugar prescription	Trials found small possible effects of ALA on blood pressure, triglycerides and, in some, blood sugar markers.	No source read describes a drug interaction. Effects found in reviews were small and inconsistent.	None found Not enough evidence ^{16 8}	Do not change any medicine because of an oil. Ask a doctor or pharmacist.
Other omega-3 products (fish, krill, cod liver or algae oil) supplement	Same family of fats; NCCIH's omega-3 page does not discuss combining products.	No interaction or harm from combining was found in the sources read.	None found Not enough evidence ²¹	Ask a pharmacist if you use more than one omega-3 product.

Who should check first 7

Situation	Advice	Evidence
Pregnancy	NCCIH says some studies suggest flaxseed is possibly unsafe in pregnancy but the evidence is not conclusive, and little is known about flaxseed oil. The official adequate intake of ALA in pregnancy is 1.4 g a day (National Academy of Medicine, 2002, via the Linus Pauling Institute); this is a food intake target, not advice to take pills. Ask a doctor or midwife before any supplement.	Authoritative guidance ^{20 18}
Breastfeeding	NCCIH says little is known about whether flaxseed is safe while breastfeeding. The adequate intake of ALA is 1.3 g a day. Ask a doctor or midwife.	Authoritative guidance ^{20 18}
Children	NCCIH does not address children. One small trial gave children with ADHD oil with ALA for 8 weeks without a reported harm in the abstract, but most children dropped out. Do not give supplements to children without asking a doctor.	Single small trial ^{5 20}
Bleeding disorders, planned surgery or blood thinners	The interaction concern is theoretical but the effect of a bleed would be serious. Ask the doctor or pharmacist managing your medicines.	Authoritative guidance (theoretical) ^{20 18}
Prostate cancer or a strong family history	Observational studies on ALA and prostate cancer are mixed and inconclusive (RR 1.08, 0.90 to 1.29). Ask a doctor before supplements.	Observational ⁴
Kidney disease	The only flaxseed oil trials read in kidney disease were in people on dialysis; safety was not the focus. Ask your kidney team before any supplement.	Gap ¹⁵
Allergy to flaxseed	Avoid flaxseed oil if you have had a reaction to flaxseed (Linus Pauling Institute reports allergic and anaphylactic reactions).	Authoritative guidance ¹⁸

Overdose, product quality and regulators

Summary. Flaxseed oil is a food-type oil and no serious poisoning from the oil was found in the sources read. The sources point to digestive upset at higher intakes, allergy, and a theoretical effect on blood thinning. No official tolerable upper intake level for ALA was found in the sources read, and the NIH Office of Dietary Supplements page that might state one could not be read.

Animal. Not reviewed.

High dose or long term signals. NCCIH says limited amounts may be safe in the short term (up to 6 months); long-term safety was not described. Higher intakes may cause bloating, fullness or diarrhoea.

Overdose response. Not described in the sources read.

Genotoxicity. Not researched.

No source read tested flaxseed oil supplements for label accuracy, pesticides or heavy metals. Oxidation (rancidity) is the main quality issue named in the sources.

Rancidity. Polyunsaturated fats oxidise more easily than saturated fats (Linus Pauling Institute). Flaxseed oil is mostly the polyunsaturated fat ALA (about 53 g per 100 g by USDA), so it is more prone to spoil than many oils. ^{18 23}

Regulation of supplements. NCCIH says the US FDA does not approve dietary supplements before they are sold; manufacturers are responsible for safety and labelling. ²⁰

Body	Action	Date
NCCIH, US National Institutes of Health (United States)	Flaxseed and Flaxseed Oil page: limited amounts may be safe short term (up to 6 months); higher amounts may cause digestive symptoms; might interact with anticoagulant or antiplatelet drugs (theoretical); pregnancy possibly unsafe but evidence not conclusive; little is known about breastfeeding; do not eat raw or unripe flaxseeds; dietary supplements are not approved by the FDA before sale. source	2025-02
NCCIH, US National Institutes of Health (omega-3 supplements) (United States)	Names flaxseed oil as an ALA supplement. Says omega-3 supplement side effects are usually mild (taste, bad breath, headache, heartburn, nausea, diarrhoea). Does not discuss blood thinner interactions. source	2024-11
US National Academy of Medicine (Food and Nutrition Board), as tabulated by the Linus Pauling Institute (United States)	Adequate intakes for ALA: babies 0.5 g a day; 1 to 3 years 0.7 g; 4 to 8 years 0.9 g; boys 9 to 13 1.2 g and girls 1.0 g; males 14 and over 1.6 g; females 14 and over 1.1 g; pregnancy 1.4 g; breastfeeding 1.3 g. These are intake targets for the general population, not advice to take supplements. source	2002 (figures); page updated 2019-05
MedlinePlus (US National Library of Medicine) (United States)	Says ground flaxseeds and flaxseed oil have the most ALA of all plant foods, and that ALA benefits the heart but not as directly as EPA and DHA. Does not discuss ALA side effects. source	2026-04-30

When to get medical help

Swelling of the face, lips or throat, trouble breathing, wheeze or a spreading rash after taking flaxseed oil: call emergency services.
Unusual bleeding, large bruises, black or bloody stools or vomit if you take blood thinners: get medical help the same day.
Severe or lasting stomach pain, or diarrhoea that does not settle: stop the oil and see a doctor.
Chest pain, sudden weakness on one side, or sudden trouble speaking: call emergency services. An oil is not a treatment for these.

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 flaxseed oil?

It is the oil pressed from flax seeds. It is the richest plant source of ALA, an essential omega-3 fat, according to MedlinePlus.

^{19 20}

What is ALA?

Alpha-linolenic acid is an omega-3 fat the body cannot make. It is different from EPA and DHA, which are found in fish and algae.

^{18 19}

Is flaxseed oil as good as fish oil?

No, they are different. The body turns only a small share of ALA into EPA and very little into DHA. Only ready-made DHA reliably raises blood DHA.

^{2 3}

What foods have plant omega-3?

By USDA data, flaxseed oil has the most (about 7.3 g ALA per tablespoon), then chia seeds (5.1 g per ounce), walnuts (2.6 g per ounce), ground flaxseed, walnut oil and canola oil.

^{23 18}

Does flaxseed oil help the heart?

A Cochrane review found that more ALA probably makes little or no difference to deaths and may slightly lower cardiovascular events, with low certainty. Trials did not test flaxseed oil alone.

^{1 9}

Does it lower blood pressure or cholesterol?

Results are mixed. One review found slightly lower blood pressure and triglycerides but slightly higher LDL cholesterol; another found no blood pressure change.

^{16 10}

Does it help with diabetes?

A review of 8 small trials in type 2 diabetes found no change in HbA1c or fasting glucose. One small gestational diabetes trial reported benefits but carries a journal expression of concern.

^{8 6 7}

Does it help skin or ADHD?

One very small trial reported better skin sensitivity and dryness. A small trial in children with ADHD found no difference from placebo, and most children dropped out.

^{12 5}

Does flaxseed oil raise cancer risk?

No clear link to prostate cancer was found in a 2013 review. A large 2021 review of cohort studies found slightly more cancer deaths with high ALA intake (RR 1.06). Both are observational.

^{4 11}

Is it safe with blood thinners?

NCCIH says flaxseed oil might interact with anticoagulant or antiplatelet drugs, and calls this theoretical. Ask a pharmacist or doctor first.

^{20 18}

Is it safe in pregnancy or for children?

NCCIH says pregnancy safety is not conclusive and little is known about breastfeeding. It does not address children. Ask a doctor or midwife before use.

²⁰

How should it be stored?

It spoils easily because it is mostly polyunsaturated fat (Linus Pauling Institute). Follow the label and do not use oil that smells sharp or bitter.

¹⁸

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We started from our existing ALA summary, read NCCIH, MedlinePlus and Linus Pauling Institute pages, re-checked food values in saved USDA FoodData Central data, and re-read PubMed abstracts for reviews and trials. Only abstracts were read for studies. The NIH Office of Dietary Supplements pages were blocked and are marked unread.
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. Trials of supplements may have industry links not stated in abstracts.

Sources 23

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

Abdelhamid AS, Brown TJ, Brainard JS et al.. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.. Cochrane Database Syst Rev. 2020. PMID 32114706. DOI 10.1002/14651858.CD003177.pub5. (abstract)
Brenna JT, Salem N Jr, Sinclair AJ, Cunnane SC; ISSFAL. alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans.. Prostaglandins Leukot Essent Fatty Acids. 2009. PMID 19269799. DOI 10.1016/j.plefa.2009.01.004. (abstract)
Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults.. Reprod Nutr Dev. 2005. PMID 16188209. DOI 10.1051/rnd:2005047. (abstract)
Carleton AJ, Sievenpiper JL, de Souza R et al.. Case-control and prospective studies of dietary alpha-linolenic acid intake and prostate cancer risk: a meta-analysis.. BMJ Open. 2013. PMID 23674441. DOI 10.1136/bmjopen-2012-002280. (abstract)
Dubnov-Raz G, Khoury Z, Wright I et al.. The effect of alpha-linolenic acid supplementation on ADHD symptoms in children: a randomized controlled double-blind study.. Front Hum Neurosci. 2014. PMID 25339885. DOI 10.3389/fnhum.2014.00780. (abstract)
Jamilian M, Tabassi Z, Reiner Z et al.. The effects of n-3 fatty acids from flaxseed oil on genetic and metabolic profiles in patients with gestational diabetes mellitus: a randomised, double-blind, placebo-controlled trial.. Br J Nutr. 2020. PMID 31902378. DOI 10.1017/S0007114519003416. (abstract)
Jamilian M, Tabassi Z, Reiner Z et al.. The effects of omega-3 fatty acids from flaxseed oil on genetic and metabolic profiles in patients with gestational diabetes mellitus: a randomized, double-blind, placebo-controlled trial - Expression of concern.. Br J Nutr. 2022. PMID 34689847. DOI 10.1017/S0007114521004037. (abstract)
Jovanovski E, Li D, Thanh Ho HV et al.. The effect of alpha-linolenic acid on glycemic control in individuals with type 2 diabetes: A systematic review and meta-analysis of randomized controlled clinical trials.. Medicine (Baltimore). 2017. PMID 28538363. DOI 10.1097/MD.0000000000006531. (abstract)
Kromhout D, Giltay EJ, Geleijnse JM; Alpha Omega Trial Group. n-3 fatty acids and cardiovascular events after myocardial infarction.. N Engl J Med. 2010. PMID 20929341. DOI 10.1056/NEJMoa1003603. (abstract)
McNabb TB, Young I, Newman RG et al.. Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults: A Systematic Literature Review and Meta-Analysis.. Curr Hypertens Rev. 2024. PMID 39558500. DOI 10.2174/0115734021337760241104063418. (abstract)
Naghshi S, Aune D, Beyene J et al.. Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of cohort studies.. BMJ. 2021. PMID 34645650. DOI 10.1136/bmj.n2213. (abstract)
Neukam K, De Spirt S, Stahl W et al.. Supplementation of flaxseed oil diminishes skin sensitivity and improves skin barrier function and condition.. Skin Pharmacol Physiol. 2011. PMID 21088453. DOI 10.1159/000321442. (abstract)
Sala-Vila A, Fleming J, Kris-Etherton P, Ros E. Impact of alpha-Linolenic Acid, the Vegetable omega-3 Fatty Acid, on Cardiovascular Disease and Cognition.. Adv Nutr. 2022. PMID 35170723. DOI 10.1093/advances/nmac016. (abstract)
Su H, Liu R, Chang M et al.. Effect of dietary alpha-linolenic acid on blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials.. Eur J Nutr. 2018. PMID 28275869. DOI 10.1007/s00394-017-1386-2. (abstract)
Tabrizi R, Azizi Z, Bazmi S et al.. The impact of flaxseed oil on lipid profiles, weight loss, and inflammatory markers in hemodialysis patients: A systematic review and meta-analysis of randomized controlled trials.. Ther Apher Dial. 2024. PMID 38726572. DOI 10.1111/1744-9987.14140. (abstract)
Yin S, Xu H, Xia J et al.. Effect of Alpha-Linolenic Acid Supplementation on Cardiovascular Disease Risk Profile in Individuals with Obesity or Overweight: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Adv Nutr. 2023. PMID 37778442. DOI 10.1016/j.advnut.2023.09.010. (abstract)
. GBIF Backbone Taxonomy: Linum usitatissimum L. (usageKey 2873861, status ACCEPTED, family Linaceae). . . (full-text)
. Linus Pauling Institute, Oregon State University: Essential Fatty Acids (page updated May 2019, reviewed June 2019). . . (full-text)
. MedlinePlus: Omega-3 fats - Good for your heart (review date 2026-04-30). . . (full-text)
. NCCIH (US National Institutes of Health): Flaxseed and Flaxseed Oil (page shows last updated February 2025). . . (full-text)
. NCCIH (US National Institutes of Health): Omega-3 Supplements: What You Need To Know (page shows last updated November 2024). . . (full-text)
. NIH Office of Dietary Supplements: Omega-3 Fatty Acids fact sheets. . . (not-read)
. USDA FoodData Central, SR Legacy (April 2018 release): fatty acids in flaxseed oil, flaxseed, chia seeds, walnuts, canola, soybean and walnut oil. . . (full-text)

Where to buy

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

The amount of the active ingredient per serving, not just the front-label claim
A third-party testing mark (USP, NSF or ConsumerLab)
Other ingredients and allergens
Ask a pharmacist about interactions with your medicines

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.