The Alternative Medical Review, Vol 14, #4, 2009 contains a monogram reveiwing DHA, Docosaexaenoic Acid, an essential omega 3 fatty acid.

DHA is a key nutrient for healthy cell membrane structure that benefits membrane ability to exchange nutrients and waste,  enzyme reactions, and communication between cells  via hormone receptors or synapses.  It is found in breastmilk, sea algae, krill, fish, grass fed livestock, and can be formed from alph-linolenic acid from seeds or nuts (such as flax, pumpkin and hemp)

DHA is critical for nerve cell membrane function and is anti-inflammatory.  It is essential for brain and visual development in fetus, infants and children, and in preserving cognitive function in adults.   Most civilized, refined diets are DHA deficient.

The cited article focuses on DHA in brain development and function.   Deficiency also is associated with autistic spectrum disorders, depression, anxiety, poor memory, maladaption to stress, inflammatory diseases such as rheumatoid and osteoarthritis, cardiovascular disease, diabetes and Alzheimers.  Generally, any disease related to impaired cell membranes will be affected by DHA nutritional status.

DHA is regarded as an essential nutrient, and as well tolerated even by infants up to at least 315 mg daily.   Pregnant or breastfeeding women are recommended to take 100 to 500 mg daily.  The International Society for the Study of Fatty Acids and Lipids recommends 300 mg daily for pregnant or breastfeeding women.  The recommended adult dosage is 0.5 - 7.0 grams daily with most clinical trials using 1-3 grams best taken with meals.