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DHA (docosahexaenoic acid)

Fatty acids are carboxylic acids with long-chain hydrocarbon side groups and play a fundamental role in many biological processes. Fatty acids are rarely free in nature but, rather, occur in esterified form as the major component of lipids. Lipids/fatty acids are sources of energy and are an integral part of cell membranes which are indispensable for processing biological or biochemical information. Polyunsaturated fatty acids (PUFA) are subdivided in classes based on the location of the first double bond counting from the methyl end of the fatty acid molecule: omega-3 fatty acids have their first double bond between the third and fourth carbon atoms, and the omega-6 fatty acids have their first double bond between the sixth and seventh carbon atoms. Particularly important are the omega-3 fatty acids and, specifically, linolenic acid (LNA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The beneficial effects of increased dietary intake of long chain omega-3 fatty acids in humans has been well documented, which includes the reduction of cardiovascular and inflammatory diseases, reduction of depression, increasing length of gestation in the third trimester, and inhibiting tumor growth. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are found naturally in marine oils. Both DHA and EPA have beneficial pharmacological effects on the human cardiovascular system, the auto-immune system and the development and maintenance of the brain and retina functions. DHA is present in large amounts in the outer segments (phospholipids) or photoreceptor cells of the retina. One naturally occurring source of DHA is fish oil. Fatty fish such as salmon, mackerel, sardines, ocean trout and herring contain the highest amounts of DHA (about 600-800 mg/3 oz). Other sources of DHA include fin fish such as whiting and flounder (about 200-400 mg/3 oz), plants such as seaweeds, and many microorganisms. DHA has been found to be required at high levels in the brain and retina for optimal mental functioning (learning ability, etc.) and visual acuity (visual performance), respectively. Therefore, dietary DHA is regarded as an essential dietary nutrient for infants and children on mixed diets. Docosahexaenoic acid (DHA) is essential for normal visual and neurological (nervous system) development in infants, and for normal brain and eye function in adults. DHA, EPA and alpha-linolenic acid lower cholesterol and neutral fat levels in the blood, and suppress aggregation of platelets. Among such PUFA's, DHA, which is present especially in rich amounts in the brain, retinas, testicles and human milk, is believed to be a substance essential for the development of the nervous system. DHA is attached via the acid group to hydrophilic drugs and renders these drugs more hydrophobic (lipophilic). Docosahexaenoic acid plays a major physiological role in those organs, and also has physiological activities such as an anti-inflammatory effect or an effect of lowering blood cholesterol level. Accordingly, docosahexaenoic acid is a useful substance, the use of which has drawn attention in the fields of medicines and food products. Recently, use of docosahexaenoic acid has also been expanded in the field of functional foods such as health foods and formulas.

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