Omega & fatty acids

Omega-3 is not a single substance but a family. ALA is the plant-based form and is found in linseed and walnuts, among other sources. EPA and DHA come from oily fish and other marine sources. The body can partly convert ALA into EPA and DHA, but this conversion is not efficient.

That is why the label of an omega-3 supplement should ideally state how much EPA and DHA it contains, not just how much fish oil. A 1000 mg fish oil capsule often contains 300 mg of EPA and DHA combined. That distinction is the first thing to look at.

For EPA and DHA there are health claims authorised by EFSA, and these are linked to a minimum daily amount. For the contribution to the normal function of the heart, this is 250 mg of EPA and DHA combined per day. For the contribution to the maintenance of normal brain function and normal vision, it is 250 mg of DHA on its own.

That gives you a practical rule of thumb: compare products on the amount of EPA and DHA per daily dose and set it against that 250 mg. The Health Council of the Netherlands recommends at least 450 mg of omega-3 per day, which equates to eating oily fish such as salmon or herring twice a week.

Cod liver oil comes from the liver of cod and, in addition to omega-3, also contains vitamins A and D. Krill oil comes from small crustaceans and provides the fatty acids in phospholipid form. Calanus oil, obtained from zooplankton, also contains astaxanthin.

Regular fish oil comes from the muscle tissue of fish rather than the liver. And then there are the animal fats that are not sources of omega-3 but do belong in this collection: beef tallow and emu oil, rich in fat-soluble nutrients.

In a supplement, the fatty acids are bound to a carrier. In fish they occur naturally as triglycerides. When fish oil is concentrated, the ethyl ester form is sometimes formed, which can then be converted back into triglyceride. In krill, the fatty acids are bound to phospholipids, the same building blocks as those of cell membranes.

Omega-3 is sensitive to oxygen, light and heat. Store liquid oil in the dark and refrigerated after opening, and observe the shelf life after opening. A fish oil that smells or tastes strong is usually oxidised.