Docosahexaenoic Acid (DHA) is a polyunsaturated fatty acid (C22H32O2) with six double bonds and is an omega-3 essential fatty acid. Fish oil is rich in DHA.
Most DHA in fish and other organisms originate from photosynthetic and heterotrophic microalgae. DHA is also commercially extractable from the microalgae Crypthecodinium chonii and Schizochytrium.
DHA produced using microalgae is vegetarian. Most animals rarely produce DHA by metabolism. Although α-linolenic acid (ALA) is also an omega-3 fatty acid, the efficiency of ALA conversion to DHA is extremely poor, and ALA cannot be used by humans, so DHA Additional supplements are required.