DOCOSAHEXAENOIC ACID (DHA) AND CHRONIC DISEASES

DHA :

Linoleic acid (LA) is an omega – 6 fatty acid and alpha-linolenic acid (ALA) is an omega-3 fatty acid are essential fatty acids for normal growth and development These fatty acids cannot be synthesized in the human body and must be obtained from the diet. These fatty acids are converted into very long chain polyunsaturated fatty acids (LC-PUFAs) through a series of desaturases and elongases.(1) LA is converted to docosahexaenoic acid (DHA) in the body, however rate of conversion varies from 0.2% and 21%.(2) The PUFA are important constituents of phospholipids. Phospholipids has been shown to be associated with normal growth and development, as well as in the outcome of chronic diseases such as coronary heart disease (CHD), hypertension, cancer, arthritis, allergies and other autoimmune diseases, since both omega-6 and omega-3 PUFAs are processed to powerful promoters of eicosanoids such as prostaglandins and leukotrienes. (3)

There is mounting literature to indicate that DHA may be of considerable benefit in the development of, retarding the progress of, or helping manage a number of chronic disorders especially cardiovascular disease/outcomes and associated risk factors. (4)

Action of DHA(5) :

(1)		Decreased production of prostaglandin E2 (PGE2) metabolites
(2)		Decrease in thromboxane A2, a potent platelet aggregator and vasoconstrictor
(3)		Decrease in leukotriene B4 formation, an inducer of inflammation and a powerful inducer of leukocyte chemotaxis and adherence
(4)		Increase in thromboxane A3, a weak platelet aggregator and a weak vasoconstrictor
(5)		Increase in prostacyclin PGI3, leading to an overall increase in total prostacyclin by increasing PGI3 without a decrease in PGI2. Both PGI2 and PGI3 are active vasodilators and inhibitors of platelet aggregation; and
(6)		Increase in leukotriene B5, a weak inducer of inflammation and a weak chemotactic agent

Thus, DHA in high doses lowers cholesterol and has antithrombotic and anti-inflammatory properties. (1)