Plants give you one omega-3, alpha-linolenic acid (ALA), in flax, chia, hemp, walnuts and rapeseed oil. The body is supposed to convert it into the two long-chain forms that the brain, the eyes and every cell membrane actually use, EPA and DHA. It does convert, a little: roughly 5 to 10 percent of ALA becomes EPA, and under 1 percent, sometimes up to 4 percent in women, becomes DHA. On a plate heavy in sunflower and corn oil, which compete for the same enzymes, the conversion falls further. The result is that vegans typically carry about half the DHA of fish eaters, and it shows in the dry, flat, low-light way the winter feels.
The signs omega-3 is low
- Dry, gritty eyes by evening; dry skin on the shins and the backs of the hands; small rough bumps on the upper arms.
- Dandruff and a dull coat, as a vet would say about a dog; brittle hair.
- Stiff, achy joints in the morning that loosen with movement.
- A low, flat mood in the dark months, poor concentration, poor sleep.
- Slow recovery after training and soreness that lingers.
None of these are specific, which is why the test below is worth doing once.
The test
The omega-3 index measures EPA plus DHA as a percentage of fatty acids in red cell membranes, from a finger-prick dried blood spot. Below 4 percent is low; 8 percent or more is the level associated with the best outcomes in the cardiovascular literature. Vegans who do not supplement commonly sit between 3 and 4 percent. Test, supplement for four months, test again; red cells turn over in about 120 days, so the second number is the honest one.
How much you need
| Reference | Amount |
|---|---|
| EPA plus DHA, EFSA adequate intake, adults | 250 mg a day |
| ALA, EFSA adequate intake | 0.5 percent of energy, about 1.1 g a day at 2,000 kcal |
| DHA in pregnancy and breastfeeding | an extra 100 to 200 mg a day |
| ALA, US adequate intake, women | 1.1 g a day |
The ALA figures are easy to reach from food. The EPA and DHA figure, in practice, is reached only with algae oil.
Vegan omega-3 foods, per serving
| Food | Serving | ALA |
|---|---|---|
| Chia seeds | 15 g (1 tablespoon) | 2.7 g |
| Ground flaxseed | 15 g (1 tablespoon) | 2.0 g |
| Walnuts | 30 g (a small handful) | 2.6 g |
| Hemp seeds, hulled | 30 g | 2.6 g |
| Rapeseed (canola) oil | 1 tablespoon | 1.3 g |
| Flaxseed oil | 1 teaspoon | 2.4 g |
| Edamame, shelled | 150 g | 0.5 g |
| Tofu, firm | 150 g | 0.4 g |
Two rules make the ALA count. Grind flax, or buy it ground and keep it in the fridge; whole seeds pass through intact. And move the kitchen oil from sunflower to rapeseed or olive, so the omega-6 competition drops and more ALA converts.
The supplement: algae oil, the direct source
Algae oil is where fish get their DHA in the first place. It raises blood DHA as well as fish oil does, in head-to-head comparisons, and carries no fish, no mercury and no bycatch.
- Dose: 250 to 500 mg of EPA plus DHA a day, combined, taken with a meal that contains some fat so it absorbs. Look for a product that states the EPA and DHA content per capsule, not just “omega-3”.
- Pregnancy and breastfeeding: at least 200 mg DHA a day on top of the above; start before conception if possible.
- If your omega-3 index tested below 4 percent: 1,000 mg EPA plus DHA a day for four months, then back to 500 mg, and retest.
- Keep the bottle in the fridge once opened; oxidised oil tastes of paint and does nothing good.
Algae oil is the one supplement on this site that costs real money. It is also the one with the clearest before-and-after on a blood test.
The one-week fix
- Buy ground flax or chia and put a tablespoon in the morning bowl every day; keep it in the fridge.
- Swap the sunflower oil for rapeseed in cooking and olive oil on the table.
- Buy an algae oil that lists at least 250 mg EPA plus DHA per capsule and take it with dinner.
- Order an omega-3 index test kit; do it now for a baseline, and again in four months.
What the research says
- Lane and colleagues, Critical Reviews in Food Science and Nutrition, 2014, narrative review of vegetarian omega-3 sources: conversion of ALA to EPA is limited and to DHA is very low, so vegans have lower DHA status; algal oil raised DHA in blood comparably to fish oil in the trials reviewed. The contrary finding: some cohorts of long-term vegans show partial upregulation of conversion, and ALA itself carries benefits of its own, so a seed-rich diet is not without value. doi.org/10.1080/10408398.2011.596292
Questions women ask
Is flaxseed enough? For ALA, yes. For DHA, no; the conversion is too low for most women to reach a comfortable blood level from seeds alone.
Algae oil or fish oil? For a vegan, algae oil, and the blood results are equivalent. Choose by the EPA and DHA milligrams on the label, not the total oil.
How long until I notice? Dry eyes and skin often improve within six to eight weeks; the index takes four months to reflect the change.