Omega-3 is an essential fatty acid that is deficient in the diets of many Americans. In the late 1970s, scientists learned that the native Inuits in Greenland, who consumed a diet very high in omega-3 fatty acids, had surprisingly low rates of heart attacks. Since that time, more than 4,500 studies have been conducted in an attempt to understand the beneficial roles that the omega-3 fatty acids play in human metabolism and health.
Docosahexaenoic acid (DHA) is the longest and most unsaturated of the omega-3 fatty acids. DHA is one of the most abundant fatty acids in the brain. In the fetus and young infant, DHA is essential for proper growth and development of the brain, nervous system, and for the retina of the eyes. Breast-feeding is extremely important because an infant receives DHA from its mother’s milk. Cow’s milk and infant formulas do not contain DHA. In Europe, law mandates that infant formulas must contain DHA.
Eicosapentaenoic acid (EPA) is a member of the omega-3 family of fatty acids. Although EPA can be consumed directly by eating certain kinds of fish, it is also produced in the body from the conversion of alpha linolenic acid (ALA). EPA is a precursor for agents in the body that provide anti-inflammatory activity, enhance the immune system, thin the blood, and lower blood pressure.
Oxidative stress is caused when there is increased oxidant production in animal cells characterized by the release of free radicals resulting in cellular damage. In humans, oxidative stress is involved in many diseases, such as cancer, Parkinson’s disease, heart failure, Alzheimer’s disease, and chronic fatigue syndrome, but short-term oxidative stress may also be important in the prevention of aging.
Previous research has shown that EPA and DHA may protect against cardiovascular disease, but some concern remained that omega-3 fatty acids may actually increase levels of oxidative stress due to their susceptibility to oxidation. Two current studies appear to have determined that omega-3 fatty acids are actually able to reduce oxidative stress by reducing levels of a compound called F2-isoprostanes. One trial included 59 overweight men with high cholesterol levels. The other trial was conducted on people with type 2 diabetes who were being treated for high blood pressure. The study participants were randomly assigned to receive either daily doses of 4 grams of EPA, DHA or olive oil (placebo) for six weeks. Researchers found that by the end of the trial, EPA reduced urine levels of F2-isoprostanes by 24 percent in the overweight men and by 19 percent in the people with type 2 diabetes, while DHA was associated with a 14 and 23 percent reduction in these groups, respectively, as compared with the olive oil group. It was also discovered that plasma levels of arachidonic acid (AA) were reduced following EPA and DHA supplementation. The researchers concluded that the changes in F2-isoprostanes most likely reflect a true reduction in oxidative stress, which supports previous research that shows EPA and DHA protects against cardiovascular disease.1
1 Mas E, Woodman RJ, Burke V, et al. The omega-3 fatty acids EPA and DHA decrease plasma F(2)-isoprostanes: Results from two placebo-controlled interventions. Free Radic Res. Jun2010.