Omega-3 Supplements: EPA, DHA, Choice and Precautions

ALA is the precursor of the family: it's essential and must come from the diet. The body converts some of it into EPA and then DHA, but, as Anses points out, this conversion rate is too low to cover DHA needs. DHA is therefore also considered essential.

Flaxseed oil or walnuts mainly provide ALA: they don't replace a direct intake of EPA and DHA. For a comparison of foods, see the article omega-3: fish, nuts, or seeds.

A product labeled "1,000 mg of fish oil" doesn't provide 1,000 mg of EPA and DHA: content varies widely between formulations. Only the line detailing both fatty acids allows a useful comparison.

Oxidation depends on light, heat, air, and time. Follow the storage instructions; a distinctly rancid smell or taste is a reason to stop using the product.

The 2020 Cochrane review pooled 86 randomized trials and 162,796 participants. It concludes, with a high level of certainty, that increasing long-chain omega-3 intake has little or no effect on overall mortality and on cardiovascular events as a whole. It suggests a possible small reduction in mortality and coronary events, with low certainty. It does confirm a roughly 15% drop in triglycerides, proportional to the dose.

Anses points out that cardiovascular prevention mainly rests on a varied diet and physical activity. For very high triglycerides or heart disease, choosing a treatment and its dose is a doctor's decision: a supplement bought online is not the equivalent of a prescribed medication.

A 2021 meta-analysis, covering 7 large trials and 81,210 participants, linked marine omega-3 supplements to a 25% increase in the risk of atrial fibrillation, a heart rhythm disorder. The risk increased by 12% at doses of 1 g per day or less and by 49% above that.

Someone with palpitations, known atrial fibrillation, or a high cardiovascular risk shouldn't start or increase a supplement without medical advice. New palpitations, feeling unwell, or chest pain warrant a prompt consultation, whether or not omega-3 is involved.

High doses can increase bleeding risk with an anticoagulant or antiplatelet medication. Mention the supplement before surgery, and seek advice in the case of chronic illness, pregnancy, breastfeeding, or an allergy to fish and seafood.

EFSA hasn't set an upper limit, but concluded in 2012 that additional intakes of up to 5 g per day of EPA and DHA pose no identified safety concern in adults. This benchmark is not a target dose.

1. 01Ask yourself whether it's your diet that needs improving, or whether there's a medical indication.
2. 02Read the EPA and DHA amounts separately, to get the actual daily dose.
3. 03Check whether the product also contains fish liver oil or vitamins A and D.
4. 04Add up the intake from all your supplements.
5. 05Seek advice if you take an anticoagulant, an antiplatelet medication, or a heart rhythm treatment.