Vegan Omega-3: Flaxseed Oil, ALA and Algae Oil Explained

Medically reviewed by Dr. Reina Punj, MBBS, PG Diploma in Endocrinology (University of South Wales), Lead Physician, Excelgenics Clinical Panel.

Omega-3 fats are essential nutrients, but the best-known sources, oily fish and fish oil, are off the menu for vegetarians and vegans. Plant foods such as flaxseed (alsi), chia and walnuts provide a different omega-3 called ALA. This guide explains the difference between ALA, EPA and DHA, how much ALA you need, what flaxseed oil capsules can and cannot do, and where algae oil fits in.

Shop Omegaco Flaxseed Oil Omega-3 Capsules →

ALA vs EPA and DHA: the key difference

"Omega-3" covers several fatty acids. The three that matter most for nutrition are:

ALA (alpha-linolenic acid) EPA (eicosapentaenoic acid) DHA (docosahexaenoic acid)
Main sources Flaxseed and flaxseed oil, chia seeds, walnuts, canola and soybean oil Oily fish, fish oil, some algae oils Oily fish, fish oil, algae oil
Essential? Yes. The body cannot make it, so it must come from food. The body can make small amounts from ALA The body can make small amounts from ALA
Official intake advice (US) Adequate intake: 1.1 g a day for women, 1.6 g for men No specific intake recommendation has been set
Suitable for vegetarians and vegans? Yes (plant sources) Only from algae oil Only from algae oil

The important point for vegetarians is that ALA is not the same as EPA and DHA. Most clinical trials of omega-3 supplements have used fish oil or other products that provide EPA and DHA directly. Those findings do not automatically apply to ALA.

How much ALA does the body convert?

The body can turn some ALA into EPA and then DHA, but the process is very limited, with reported conversion rates of less than 15%. In small studies of healthy young adults, men converted about 8% of ALA to EPA and 0–4% to DHA, while women converted more (about 21% to EPA and 9% to DHA), possibly because of oestrogen. ALA also competes with the omega-6 fat linoleic acid for the same enzymes. Many common cooking oils, such as sunflower and safflower oil, are rich in linoleic acid and contain little ALA.

So a flaxseed oil capsule is a good way to add ALA to your diet, but it is not a like-for-like replacement for fish oil.

Vegan omega-3 options compared

Option What it provides Things to know
Flaxseed oil capsules ALA Convenient and measured. No EPA or DHA. Flaxseed oil does not contain the lignans or fibre found in whole flaxseed.
Flaxseed oil (bottle) ALA: about 7.3 g per tablespoon The richest common food source of ALA
Ground flaxseed, chia seeds, walnuts ALA, plus fibre and other nutrients Chia: about 5.1 g ALA per 28 g; walnuts: about 2.6 g per 28 g
Algae (algal) oil capsules DHA, and in some products EPA The main vegan source of EPA and DHA. Products usually provide about 100–300 mg DHA. (Excelgenics does not currently sell an algae oil.)
Fish oil EPA and DHA Not suitable for vegetarians or vegans

What to look for in flaxseed oil capsules

What to check Why it matters Omegaco
Oil per capsule Tells you how much flaxseed oil you get. 560 mg cold-pressed flaxseed oil
ALA per capsule ALA is the omega-3 in flaxseed oil. An estimated ~300 mg ALA
EPA and DHA A clear label should not imply that flaxseed oil provides them. None: Omegaco contains ALA only
Capsule type Many omega-3 softgels use gelatin. Plant-based vegetarian capsule
Other ingredients Fewer additives is simpler. No preservatives, no fish derivatives

One capsule of Omegaco provides roughly a fifth to a quarter of the adult adequate intake for ALA. The rest should come from food, such as a spoonful of ground flaxseed or a handful of walnuts.

Flaxseed oil and omega-3: what the research says

ALA is incorporated into cell membranes throughout the body. In Europe, ALA is authorised to be described as contributing to the maintenance of normal blood cholesterol levels, with the beneficial effect obtained from a daily intake of 2 g of ALA. One Omegaco capsule provides an estimated 300 mg, well below that amount, so most ALA would need to come from food.

A 2012 meta-analysis of 27 observational studies (about 251,000 people) found that people with higher dietary ALA intake had a moderately lower risk of cardiovascular disease. This shows an association, not cause and effect, and does not show that an ALA supplement reduces risk.

For other uses, the evidence for flaxseed oil is limited. A 2023 review described possible anti-inflammatory effects, but this rested mainly on proposed mechanisms and experimental work rather than human trials. In a small trial in 22 people with rheumatoid arthritis, three months of ALA from flaxseed raised blood ALA but not EPA or DHA, and did not improve clinical or laboratory measures compared with placebo. If joints are your main interest, see our Joint Supplements Guide.

How to take flaxseed oil capsules

  • Dose: follow the label. For Omegaco, that is 1 capsule a day.
  • With a meal: take it with a meal that contains some healthy fat.
  • Make food do most of the work: add ALA-rich foods such as ground flaxseed, chia or walnuts to reach the adequate intake.
  • Balance your oils: using a variety of cooking oils, rather than relying only on sunflower or safflower oil, helps balance omega-6 and omega-3 intake.
  • Thinking about EPA and DHA? If you want these specifically, for example during pregnancy, an algae oil may be more relevant than flaxseed oil. Discuss it with your doctor.

Flaxseed oil side effects and safety

Flaxseed oil is generally well tolerated. Higher doses can cause digestive symptoms such as bloating, a feeling of fullness or diarrhoea. Points to keep in mind:

  • Blood thinners: flaxseed oil might add to the effect of anticoagulant or antiplatelet medicines, such as warfarin or aspirin. Speak to your doctor before use if you take them.
  • Pregnancy and breastfeeding: little is known about the safety of flaxseed oil supplements during pregnancy or breastfeeding, so avoid use unless your doctor advises it.
  • Medicines and health conditions: if you take any regular medicine, or have a diagnosed condition, check with your doctor or pharmacist first.
  • Do not exceed the recommended daily dose.

Who might consider a vegan omega-3 supplement?

  • Vegetarians and vegans, who get no omega-3 from fish
  • People who rarely eat flaxseed, chia or walnuts
  • Anyone who prefers to avoid fish-derived products, or dislikes the aftertaste of fish oil

Plant-based eaters may also want to read our guides to CoQ10 supplements, since food sources of CoQ10 are mainly meat and fish, and magnesium supplements.

Frequently asked questions

What is the best vegan omega-3 supplement?

It depends on what you want. For ALA, flaxseed oil capsules are a simple, measured option. For EPA and DHA without fish, algae oil is the main vegan source. Whichever you choose, check that the label states the amount of each omega-3 and does not imply that flaxseed oil contains EPA or DHA.

Is flaxseed oil as good as fish oil?

They are not interchangeable. Flaxseed oil provides ALA; fish oil provides EPA and DHA. The body converts only a small proportion of ALA into EPA and DHA, so research on fish oil should not be applied to flaxseed oil.

Do vegetarians need omega-3 supplements?

Not necessarily. ALA is the only omega-3 that is strictly essential, and a diet that regularly includes flaxseed, chia or walnuts can provide enough. A supplement can help if these foods are rarely eaten. Pregnant vegetarians and vegans should ask their doctor whether they need EPA and DHA.

Is ground flaxseed or flaxseed oil better?

Ground flaxseed provides ALA plus fibre and lignans. Flaxseed oil provides more concentrated ALA but no fibre, and lignans are not found in the oil.

Can I take flaxseed oil every day?

Flaxseed oil capsules are intended for daily use at the dose on the label. The NCCIH notes that flaxseed oil in limited amounts may be safe for short-term use (up to 6 months), so review longer-term use with your doctor. Speak to your doctor first if you take blood-thinning medicines, or are pregnant or breastfeeding.

Further reading

See Omegaco Flaxseed Oil Omega-3 Capsules →

References

  • National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. ods.od.nih.gov
  • Linus Pauling Institute, Oregon State University. Essential Fatty Acids. lpi.oregonstate.edu
  • Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reproduction Nutrition Development. 2005;45(5):581–597. doi:10.1051/rnd:2005047
  • Commission Regulation (EU) No 432/2012, list of permitted health claims (alpha-linolenic acid). eur-lex.europa.eu
  • Pan A, Chen M, Chowdhury R, et al. α-Linolenic acid and risk of cardiovascular disease: a systematic review and meta-analysis. American Journal of Clinical Nutrition. 2012;96(6):1262–1273. doi:10.3945/ajcn.112.044040
  • Al-Madhagy S, Ashmawy NS, Mamdouh A, Eldahshan OA, Farag MA. A comprehensive review of the health benefits of flaxseed oil in relation to its chemical composition and comparison with other omega-3-rich oils. European Journal of Medical Research. 2023;28:240. doi:10.1186/s40001-023-01203-6
  • Nordström DC, Honkanen VE, Nasu Y, et al. Alpha-linolenic acid in the treatment of rheumatoid arthritis. A double-blind, placebo-controlled and randomized study: flaxseed vs. safflower seed. Rheumatology International. 1995;14:231–234. doi:10.1007/BF00262088
  • Linus Pauling Institute, Oregon State University. Lignans. lpi.oregonstate.edu
  • National Center for Complementary and Integrative Health (NIH). Flaxseed and Flaxseed Oil. nccih.nih.gov

This information is for general education and is not medical advice. Food supplements are not intended to diagnose, treat, cure or prevent any disease. Consult a qualified healthcare professional before starting any supplement, particularly if you are pregnant, breastfeeding, have a medical condition or take medication.