The omega-3s DHA and EPA are long-chain, polyunsaturated fatty acids essential to human health and development. They are found primarily in seafood, and omega-3 supplements are usually produced from fish oil. While some types of ocean fish contain dangerous levels of mercury, the oil in many supplements has been purified to ensure its safety.
Omega-3 Importance
A diet high in omega-3 fatty acids reduces the risk of heart disease and atherosclerosis, improves cholesterol levels, decreases the risk of arrhythmias and lowers blood pressure. Boosting omega-3 consumption has been shown to dramatically reduce mortality in survivors of a heart attack. Omega-3 fatty acids also support growth and development of the brain, eyes and central nervous system.
Mercury
Mercury is a heavy metal toxin that occurs naturally in the environment Healthy people have low concentrations of mercury in their blood, approximately 3 to 6 micrograms per liter. However, in large, long-lived predatory fish and marine animals, mercury accumulates and reaches potentially dangerous levels. Other hazardous toxins in seafood include polychlorinated biphenyls, or PCBs, and dioxins.
Supplements
Some fish oil supplements are derived from a specific species of fish, usually small, low-mercury fish such as anchovies and sardines. You can find this information on the packaging. All omega-3 supplements in the United States are subject to strict manufacturing and purification practices. The label should include the manufacturer's location and the results of third-party laboratory testing for environmental toxins. Stick with well-known brands that list this information right on the package.
Other Sources
You can also obtain omega-3 fatty acids directly from food sources. Cold water, fatty fish are the richest source of the omega-3 fatty acids EPA and DHA. To keep your mercury exposure low, avoid large predatory fish such as shark, swordfish, king mackerel or tilefish. You may safely consume two servings per week of low-mercury fish such as canned light tuna, salmon, pollock and catfish. Another type of omega-3, alpha-linolenic acid, is found in plant sources such as leafy green vegetables, walnuts, soy and flaxseed. Your body converts this short-chain ALA into the long-chain fatty acids EPA and DHA very inefficiently.
References
- American Heart Association: Fish and Omega-3 Fatty Acids
- MayoClinic.com: Omega-3 Fatty Acids, Fish Oil, Alpha-Linolenic Acid
- "Archives of Pathology & Laboratory Medicine"; "Measurement of Mercury Levels in Concentrated Over-the-Counter Fish Oil Preparations: Is Fish Oil Healthier than Fish?; S.E. Foran et al.; December 2003
- American Pregnancy Association: Omega-3 Fish Oil and Pregnancy
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