Omega 3’s are a group of unsaturated fatty acids, and include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

Omega 3’s are a group of unsaturated fatty acids, and include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). 

DHA fatty acid is the primary oil in fish, which has been shown to have some health benefits, including the reducing of heart disease by lowering blood triglyceride levels.

DHA is also the primary fatty acid in the human brain, and the deficiency has been linked to cognitive decline and possibly Alzheimer’s disease.

ALA is the shortest chain fatty acid, and predominant in plant-based sources of omega-3’s.  

EPA and DHA have the most research for health benefits, and are mostly available in seafood.  The body can convert some of the ALA consumed from foods into EPA and DHA in the body, but in a much smaller amount than eating foods rich in DHA.

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http://m.lifesdha.com/health-benefits-of-dha.aspx

Docosahexaenoic acid,

(DHA) is a polyunsaturated omega-3 fatty acid found throughout the body. It is a major structural fat in the brain and retina accounting for up to 97% of the omega-3 fats in the brain and up to 93% of the omega-3 fats in the retina. It is also a key component of the heart. Numerous studies confirm that everyone, from infants to adults, benefits from an adequate supply of DHA.