Docosahexaenoic acid (DHA) is a 22-carbon-chain, omega-3 essential fatty acid with six double bonds. These six double bonds make it a polyunsaturated fatty acid. It is similar to eicosapentaenoic acid (EPA) in its structure and can be converted from EPA in the body. DHA occurs naturally in the human body and is found in rich amounts in brain tissues. However, it is an essential fatty acid because it cannot be synthesized in the body and must come from dietary sources. The richest source of DHA and EPA is fish oil.

EPA and DHA belong to a class of compounds called eicosanoids. Prostaglandins, prostacyclins, thromboxanes and leukotrienes are all eicosanoids and are biologically active compounds. In general, DHA and EPA promote the formation of beneficial eicosanoids. The following research will describe how DHA impacts human health through eicosanoid mediators.

DHA is a fatty compound and is absorbed into the phospholipid bi-layer (fatty perimeter) of cells. It is here that is it thought to exert its biochemical properties. DHA is highly concentrated in the brain (30% of brain gray matter is DHA) and retinal neural membranes and is important in photo transduction (turning light into a chemical message) and neuronal function.

Nervous System Health

DHA protects nervous tissues (brain and eye) and cardiovascular tissues by preventing oxidation and inflammation.

DHA is required for brain development and appears to help young children as they develop mental skills. Children who have adequate levels of DHA in their diets develop ocular and cognitive skills at a rate greater than DHA-deprived children. Infants gather DHA from the placenta while in the womb and from human breast milk when nursing. 

In 2001, the FDA allowed DHA to be added to infant formula. Not only does DHA help infant brain development, it may also prevent post-partum depression in nursing mothers. Daily dietary DHA intake is the lowest among women in the u.s. (40-50 mg/day) compared to European woman (200 mg/ day) and Japanese women (600 mg/ day). While DHA plays an important role in the development of the nervous system, it also protects nervous tissues and may be of benefit in preventing nerve damage. 

DHA is required not only for brain tissue formation and maintenance but also for ocular health. It provides membrane fluidity in the retina and may also prevent oxidative damage to photo receptors in the retina and retinal neuronsy, Research also suggests benefits from the use of DHA in ophthalmic disorders like glaucoma. Human adults maintain a constant level of DHA in brain tissue. Supplementation of DHA may be helpful in the prevention of psychological disorders such as schizophrenia and depression. Diets rich in omega-3 fatty acids, including DHA, may help reduce the risk of developing Alzheimer’s disease. Alzheimer’s patients have lower cellular levels of DHA than control groups. Overall, lower levels of brain DHA is associated with cognitive impairment. 

Cardiovascular Health 

Research indicates that DHA reduces levels of blood triglycerides and decreases the risk of developing coronary heart disease (CHD) DHA also increases the highdensity lipoprotein (HDL) portion of the total cholesterol, which is considered “good cholesterol.” Higher levels of HDL in comparison to LDL indicate a much lower risk of developing CHD. The omega-3 fatty acids DHA and EPA have been shown to help prevent the onset of atherosclerosis possibly due to a reduction in inflammatory response. DHA promotes the formation of Thromboxane A2 (prostaglandin) that has an overall effect of reducing blood clotting and reducing inflammation.

DHA also promotes nitric oxide (NO) formation, which dilates blood vessels and promotes healthy blood flow. DHA promotes the formation of leukotriene B5. Leukotriene B5 suppresses immune cell adhesion (activation), which is part of the inflammatory response. DHA accomplishes this by promoting the formation of beneficial eicosanoids that tend to inhibit inflammation. This immune suppression and anti-inflammatory activity has been shown to be helpful in autoimmune and inflammatory diseases such as: rheumatoid arthritis, Crohn’s disease, ulcerative colitis, psoriasis, lupus erythematosus, multiple sclerosis and migraine headaches. 

In summary, DHA protects nervous tissues (brain and eye) and cardiovascular tissues by preventing oxidation and inflammation. It accomplishes this through mediators involving blood clotting and immune modulation. Many of the benefits of DHA are also claimed for EPA since EPA is converted to DHA in the body. 

Nature’s Sunshine DHA provides 250 mg DHA plus 50 mg EPA per softgel.

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Posted: 02/10/2009 at 01:53 PM
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Posted: 02/10/2009 at 01:53 PM
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