It is found in high concentrations in the species Ulkenia, Pavlova and in the heterotrophic species Schizochytrium. They form the basis for the supply of docosahexaenoic acid in the marine food chain. Via fish and, above all, fish meal, fish oil and oil, it finally reaches the human diet. Man synthesizes DHA from α-linolenic acid, which is therefore classified as essential.
Studies show that about 5-10% of the absorbed –-linolenic acid is converted to EPA and 2-5 % to DHA. Other studies speak of conversion rates to EPA and DHA below 5%. According to the International Society for the Study of Fatty Acids and Lipids, it is not possible to increase the level of DHA in the blood by supplementing additional ALA, EPA or other precursors.
Since the intake of omega-3 fatty acids and especially docosahexaenoic acid in Europe is significantly below the recommendations, DHA has been offered in the form of capsules and foods enriched with docosahexaenoic acid for several years. Fish can produce this fatty acid themselves. The absorbed short-chain omega-3 fatty acids are metabolized by desaturases and elongases to docosahexaenoic acid. In addition to the fish cells’ own capacity to synthesize the fatty acids themselves, they also accumulate docosahexaenoic acid by absorbing docosahexaenoic acid-containing microalgae and plankton.
A commission of experts appointed by the EU advises pregnant women to take at least 200 mg docosahexaenoic acid per day, which should have a positive effect on the development of the eye and brain functions of the unborn child.