What is EPA and DHA?

Eicosapentaenoic acid (EPA)

EPA or also know as icosapentaenoic acid is an omega-3 fatty acid. EPA is a polyunsaturated fatty acid that acts as a precursor for prostaglandin-3 (which inhibits platelet aggregation), thromboxane-3 and leukotriene-5 groups (all eicosanoids). It is obtained in the human diet by eating oily fish or fish oil—cod liver, herring, mackerel, salmon, menhaden and sardine. It is also found in human breast milk.

It is available from some non-animal sources—spirulina and microalgae. Microalgae are being deveolped as a commercial source. EPA is not usually found in higher plants, but it has been reported in trace amounts in purslane.

The US National Institute of Health's MedlinePlus lists a large number of conditions in which EPA (alone or in concert with other ω-3 sources) is known or thought to be effective. Most of these involve its ability to lower inflammation.

Docosahexaenoic acid (DHA)

DHA is most often found in fish oil. Most of the DHA in fish and other more complex organisms originates in microalgae of the genus Schizochytrium, and concentrates in organisms as it moves up the food chain. Most animals make very little DHA metabolically, however small amounts are manufactured internally through the consumption of α-linolenic acid, an omega-3 fatty acid found in chia, flax, and many other seeds and nuts.

DHA is a major fatty acid in sperm and brain phospholipids, and especially in the retina. Dietary DHA can reduce the level of blood triglycerides in humans, which may reduce the risk of heart disease. Low levels of DHA cause reduction of brain serotonin levels and have been associated with ADHD, Alzheimer's disease, and depression, among other diseases, and there is mounting evidence that DHA supplementation may be effective in combating such diseases.

DHA and EPA are Essential fatty acids, or EFAs

EFA's are fatty acids that are required in the human diet; they must be obtained from food as human cells have no biochemical pathways capable of producing them internally. There are two families of EFAs: ω-3 (or omega-3 or n-3) and ω-6 (omega-6, n-6.) Fats from each of these families are essential, as the body can convert one omega-3 to another omega-3, for example, the body cannot create an omega-3 from scratch. They were originally designated as Vitamin F when they were discovered as essential nutrients in 1923. In 1930, work by Burr, Burr and Miller showed that they are better classified with the fats than with the vitamins.