Omega-3: what they really do for you and how to choose the right ones

Omega-3s are among the few supplements for which there is a consensus on their benefits. However, it is still important to understand what they actually provide, and at what dose.

EPA and DHA: the two that matter

The term ‘omega-3’ covers several fatty acids. Only three are of practical importance: ALA, which is plant-based (walnuts, rapeseed, flaxseed), and, most importantly, EPA and DHA, found in oily fish. The body is very poor at converting ALA into EPA and DHA — converting only a few per cent — which explains why a diet rich in vegetable oils is not sufficient to meet our needs.

What the data show

European food safety authorities recognise that EPA and DHA contribute to the normal functioning of the heart, at doses of 250 mg per day or more. DHA also helps maintain normal vision and brain function. These are regulated claims, not therapeutic promises: a supplement neither treats nor prevents disease.

What dose, what quality?

• Usual dose: 250 to 1,000 mg of combined EPA + DHA per day.
• Check the actual dosage: a capsule labelled ‘1,000 mg of fish oil’ often contains only 300 mg of EPA + DHA. It is this second figure that matters.
• Freshness: omega-3s oxidise. A distinct rancid smell or taste indicates that the product has gone off.
• Storage: keep away from light and heat; store in the fridge once opened.

If you eat oily fish two to three times a week, your intake is probably sufficient. If not, taking a supplement is one of the most sensible options to consider.

Precautions

At high doses, omega-3s can thin the blood. If you are taking anticoagulant medication or have a planned surgical procedure, medical advice is essential.

This information is provided for guidance only and is not a substitute for the advice of a healthcare professional. If you have a medical condition, are currently undergoing treatment, are pregnant or breastfeeding, consult your doctor before taking any supplements.