Flaxseed Oil and Plant-Based Omega-3 (ALA)
Flaxseed oil and other plant omega-3 sources supply ALA, not EPA or DHA. See what Cochrane and NCCIH say, the conversion debate, an official ALA intake, food options and safety.
Content last updated . This page has not been medically reviewed.
What is Flaxseed oil and plant omega-3 (ALA) good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Plant source of omega-3 (ALA)
Established roleFlaxseed oil is a concentrated plant source of alpha-linolenic acid (ALA), an omega-3 fat. ALA is a different fat from the EPA and DHA found in fish and algae.
Supplements: Being a source of ALA is what the oil is; it does not by itself show a health benefit from taking the supplement.
Heart and blood vessel health
Preliminary or mixedIn a large Cochrane review, eating more ALA may slightly lower heart and blood vessel events, but the certainty was low.
Supplements: Small and uncertain: little or no effect on deaths; possible slight fall in cardiovascular events (low certainty).
Heart rhythm
Preliminary or mixedThe Cochrane review found that more ALA probably slightly lowers the risk of irregular heartbeat, based on two trials.
Supplements: Based on few trials; not a reason to use flaxseed oil to treat a rhythm problem.
Blood sugar measures in gestational diabetes
Preliminary or mixedNCCIH says some research suggests flaxseed oil with ALA might improve fasting measures and insulin resistance in pregnant people with gestational diabetes.
Supplements: Preliminary; unclear for other kinds of diabetes. Only under a clinician's care in pregnancy.
Making EPA and DHA in the body
Preliminary or mixedThe body can turn some ALA into EPA, but very little into DHA. Reviews found supplemental ALA raises blood EPA and DPA but has little effect on DHA.
Supplements: Flaxseed oil should not be treated as a DHA source.
Weight loss
Not enough evidenceNCCIH says flaxseed oil supplements do not seem to help with weight loss.
Supplements: No benefit seen for weight loss.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (1)
- Heart HealthPreliminary or mixed
Eating more ALA may slightly lower heart and blood vessel events, but the Cochrane review rated the certainty as low and found little or no effect on deaths.
Body systems (2)
- Cardiovascular SystemPreliminary or mixed
Eating more ALA may slightly lower heart and blood vessel events, but the Cochrane review rated the certainty as low and found little or no effect on deaths.
- Heart & CirculationPreliminary or mixed
Eating more ALA may slightly lower heart and blood vessel events, but the Cochrane review rated the certainty as low and found little or no effect on deaths.
Body parts (1)
- HeartPreliminary or mixed
Cochrane found ALA probably slightly lowers irregular heartbeat risk (2 trials) and may slightly lower cardiovascular events (low certainty).
Functional actions (1)
- Cardiovascular SupportPreliminary or mixed
Eating more ALA may slightly lower heart and blood vessel events, but the Cochrane review rated the certainty as low and found little or no effect on deaths.
Biomarkers (1)
- Omega-3 IndexPreliminary or mixed
Supplemental ALA raises blood EPA and DPA but has little effect on DHA, so it is a weak way to raise the Omega-3 Index; a blood level is a marker, not a health outcome.
Conditions & symptoms (3)
- Cardiovascular DiseasesPreliminary or mixed
More ALA may slightly lower cardiovascular events (low certainty); it probably makes little or no difference to deaths.
- Cardiac ArrhythmiaPreliminary or mixed
Two trials suggest ALA probably slightly lowers arrhythmia risk (moderate certainty).
- Gestational DiabetesPreliminary or mixed
Some research suggests flaxseed oil may improve fasting measures and insulin resistance; limited and only for blood measures.
Documented risks and interactions (4)
- Possible interaction with blood thinners. NCCIH notes there are theoretical reasons to suspect flaxseed oil could interact with anticoagulant or antiplatelet drugs, so talk to a provider first if you take any medicine.
- Pregnancy and breastfeeding caution. NCCIH says some studies of flaxseed in pregnancy suggest it may be unsafe, though the evidence is not conclusive, and little is known about flaxseed oil in pregnancy or breastfeeding.
- Digestive side effects. NCCIH says limited amounts may be safe for up to 6 months, while higher amounts may cause bloating, fullness and diarrhea.
- Raw or unripe flaxseeds. NCCIH says not to eat raw or unripe flaxseeds because they may contain potentially toxic compounds.
What plant omega-3 is
Flaxseed oil contains ALA (alpha-linolenic acid), a plant omega-3. [3] MedlinePlus lists ground flaxseeds, flaxseed oil, walnuts, chia seeds, canola and soy oil, soybeans and tofu as plant sources, and says ground flaxseeds and flaxseed oil have the highest amount of ALA of all plant foods. [4] ALA is a different fat from the EPA and DHA in fish and algae; see ALA, EPA and DHA. Whole foods are on their own pages: flaxseed, chia seeds and walnuts; other oils are compared in chia, hemp, perilla and walnut oils. The fish-oil comparison is in flaxseed oil vs fish oil.Official ALA intake
| Group | Adequate Intake of ALA | Source and year |
|---|---|---|
| Adult men, 19 years and over | 1.6 g a day | Health Canada, dietary reference intakes table, page modified 2025 [5] |
| Adult women, 19 years and over | 1.1 g a day | Health Canada, 2025 [5] |
| Pregnancy, ages up to 50 | 1.4 g a day | Health Canada, 2025 [5] |
| Lactation, ages up to 50 | 1.3 g a day | Health Canada, 2025 [5] |
These are Canadian reference values for the nutrient ALA from all sources, not a target for flaxseed oil. ALA figures from the NIH Office of Dietary Supplements and EFSA could not be verified, because those sites blocked our download.
Flaxseed oil compared with fish oil
Evidence labels: mixed, promising but limited, insufficient evidence, no benefit shown. Cochrane tested ALA and long-chain omega-3 (EPA and DHA) separately, so fish-oil findings do not apply to flaxseed oil.| Question | What the sources found | Label |
|---|---|---|
| Heart events | Cochrane (2020): more ALA probably makes little or no difference to all-cause death (RR 1.01) or cardiovascular death (0.96); it may slightly reduce cardiovascular events (RR 0.95, 95% CI 0.83 to 1.07, low certainty) and probably slightly reduces arrhythmia (0.73, 2 trials, moderate certainty). [6] | Limited, low to moderate certainty |
| Weight loss | NCCIH: flaxseed oil supplements don't seem to help with weight loss. [1] | No benefit shown |
| Gestational diabetes | NCCIH: some research suggests ALA-containing flaxseed oil supplements might improve fasting measures and insulin resistance in pregnant people with gestational diabetes. [1] | Promising but limited; blood measures |
| Other diabetes uses | NCCIH: unclear whether flaxseed oil helps other people with diabetes, such as those with diabetic foot ulcers. [1] | Insufficient evidence |
| Making EPA and DHA | A 2009 review found supplemental ALA raises EPA and DPA in blood but has little effect on DHA, which preformed DHA does raise. [7] A 2022 opinion argued conversion is nutritionally adequate. [8] A 2026 review found vegan diets linked to lower EPA and DHA status. [9] | Mixed: conversion is limited and debated |
ALA, EPA and DHA are not interchangeable, and conversion varies between people. A blood level is a biomarker, not a clinical outcome.
Plant-based eating
The NHS lists flaxseed (linseed) oil, rapeseed oil, walnuts and omega-3-enriched eggs as vegetarian omega-3 sources. [10] For vegans it lists ground linseed (flaxseed) oil, rapeseed oil, chia seeds, shelled hemp seeds and walnuts. [11] If a direct DHA source is wanted, see algal oil and omega-3 for vegetarians and vegans.Frequently asked questions
Is flaxseed oil as good as fish oil?
Not shown. Cochrane tested ALA and long-chain omega-3 separately, and ALA's effects were small or uncertain. [6]
Does flaxseed oil provide EPA and DHA?
It provides ALA. [3] Supplemental ALA raised EPA but had little effect on DHA in one review; how much converts is debated. [7][8]
How much ALA do adults need?
Health Canada lists an Adequate Intake of 1.6 g a day for adult men and 1.1 g a day for adult women (all sources of ALA). [5]
Is flaxseed oil safe for everyone?
NCCIH advises caution with anticoagulants and in pregnancy, and says not to eat raw or unripe seeds. [1]
Is flaxseed oil vegan?
It is a plant oil, and the NHS lists it among omega-3 sources suitable for vegetarians. [10] Check the capsule shell if buying capsules.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Quick safety points first
- Raw seeds. NCCIH says not to eat raw or unripe flaxseeds because they may contain potentially toxic compounds. [1]
- Blood thinners. NCCIH says there are theoretical reasons to suspect flaxseed or flaxseed oil might interact with anticoagulant or antiplatelet drugs, and to talk with your provider before using it if you take any medicine. [1] Tell your surgical team about supplements before an operation. [2] Never stop a prescribed medicine yourself; ask the prescriber or a pharmacist.
- Pregnancy and breastfeeding. NCCIH says some studies of flaxseed in pregnancy suggest it is possibly unsafe, though the evidence is not conclusive, and little is known about flaxseed oil in pregnancy or while breastfeeding. [1] Ask your clinician; see pregnancy and breastfeeding safety.
Other safety points
- Duration and digestion. NCCIH says limited amounts of oral flaxseed oil may be safe in the short term (up to 6 months); higher amounts may cause bloating, fullness and diarrhea. [1]
- Children, older adults, kidney or liver conditions. We found no flaxseed-oil-specific advice for these groups (Proper evidence not found). Ask a clinician.
- Quality. The oxidation and label studies we read tested fish oils, not flaxseed oil, so for flaxseed oil: Proper evidence not found. Follow the label's storage directions and see quality testing and certifications.
- Medicines. See medication interactions.
References
- NCCIH, Flaxseed and Flaxseed Oil. Read 2026-10-22.
- NCCIH, Using Dietary Supplements Wisely. Read 2026-10-22.
- NCCIH, Omega-3 Supplements: What You Need To Know. Read 2026-10-22.
- MedlinePlus, Omega-3 fats - Good for your heart. Read 2026-10-22.
- Health Canada, Dietary reference intakes tables: Reference values for macronutrients. Read 2026-10-22.
- Abdelhamid AS et al., Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease, Cochrane Database Syst Rev 2020. Read 2026-10-22.
- Anderson BM, Ma DW, alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans, 2009. Read 2026-10-22.
- α-linolenic acid interconversion is sufficient as a source of longer chain ω-3 polyunsaturated fatty acids in humans: An opinion, 2022. Read 2026-10-22.
- Vegetarian Diets and Their Effect on n-3 Polyunsaturated Fatty Acids Status in Humans: Systematic Review, 2026. Read 2026-10-22.
- NHS, Fat: the facts. Read 2026-10-22.
- NHS, The vegan diet. Read 2026-10-22.