More than 30 years ago, news about omega-3 fatty acids and their potential positive impacts on the health of Eskimos were met with numerous research studies to investigate claims further. Not all hopes for the positive effects of fish oil were confirmed by science, but researchers did make many very important, solid connections between omega-3 and healthy bodies.
History
Low cardiovascular death rates in Eskimos raised interest in exploring their mainly fish-based diets. Similar effects were seen in other Asian populations. The National Institutes of Health's Office of Dietary Supplements funded eight evidence-based reviews of studies on omega-3 for the prevention and treatment of several diseases. The reviews were published in 2004 and 2005. Their final conclusion -- that further investigation is warranted on omega-3's health effects -- did not deter nutrition organizations and the media from trumpeting the good news about omega-3 and health. By 2007, the National Center for Health Statistics and the National Center for Complementary and Alternative Medicine found in a survey that omega-3 supplements were extraordinarily well-received supplements in American households, becoming the most common nonvitamin/nonmineral natural product taken by adults.
Omega-3: What It Is and How It Works
Omega-3 is a polyunsaturated fatty acid that is essential and only derived from food or supplements; the body does not make its own omega-3. There are three types: alpha-linolenic acid, or ALA; eicosapentaenoic acide, or EPA; and docosahexaenoic acid, or DHA. Primary sources of EPA and DHA are fatty fish such as salmon, mackerel, herring, and tuna, and their oils, as well as algae oil. ALA is found in vegetable sources and converts to EPA and DHA after being eaten. The National Institutes of Health Office of Dietary Supplements explains the biochemical details of how omega-3 acids are used by the body. ALA is converted into EPA and DHA. Metabolized EPA becomes an eicosanoid, similar to prostaglandins and leukotrienes, that regulates cell and muscular function, blood clotting, hormone and digestive secretions, and the use of other nutrients by cells. DHA bathes the brain and is involved in both neuron signal transmission and in protecting the brain against inflammation.
Conditions That Are Improved by Omega-3
The University of Maryland Medical Center lists numerous conditions thought to be positively affected by omega-3 fatty acids. Claims have only been substantiated, however, for cardiovascular disease and rheumatoid arthritis. According to the NIH Office of Dietary Supplements, omega-3 decreases triglycerides, offering a small benefit to blood pressure and possibly helping patients with atherosclerosis. Omega-3 appears to help normalize heart rate and coronary blood flow. Including omega-3 in the diet was found to reduce mortality overall and specifically in cases of cardiac related death. Patients with rheumatoid arthritis who used omega-3 experienced reduced joint pain and less need for corticosteroids.
Health Conditions That Need More Research
Studies were conducted to explore the effects of omega-3 on several health conditions and for some, the evidence was inconclusive and more research is needed. These conditions include asthma, dementia, diabetes, inflammatory bowel disease, lupus, osteoporosis, and renal disease. Other uses of omega-3 that have yet to be conclusively proven effective include for the treatment of depression, bipolar disorder, schizophrenia, attention deficit/hyperactivity disorder, menstrual pain, macular degenerative eye disease and various cancers.
Sources of Omega-3
The best and most well-known food sources for omega-3 are fatty fish such as salmon, tuna, and halibut. For people who don't like fish but who want an omega-3 boost, capsule supplements using fish oil have become popular. Flaxseed, which is found in both oil and ground meal, is an excellent vegetarian source. Other seed sources are hemp seeds, chia seeds, pumpkin seeds, and rapeseed oil. Soybeans and soybean oil provide omega-3. Vegetables, too, can provide omega-3. The Vegetarian Society says walnuts, cabbage, Brussels sprouts, broccoli, spinach, and kale have omega-3, although in much smaller quantities than meats.
How Much Omega-3 to Take
Unless a health care provider has prescribed otherwise, adults should not take more than 3 g daily of omega-3 in capsule form. To derive most of your omega-3 from food sources, recommendations are for heart-healthy adults to eat fish at least twice weekly. Adults with coronary heart disease and/or high cholesterol are advised to use supplements under the supervision of their physician. Children are not advised to take omega-3 supplements unless specifically directed by a health care provider. Vegetarians should consult a nutritionist or physician to determine if their daily dietary intake is adequate or if supplementation is necessary.
Precautions
High doses of omega-3 fatty acids can promote bleeding and so must be used with caution in some instances, for example, if a bleeding disorder exists. The possibility of negative interactions with other drugs exists for those taking diabetes medications or blood-thinners. Because fish often contain contaminants from the water, such as mercury, dioxins, and PCBs, fish and fish products such as supplements should be purchased only from reputable sources that test for toxic residues.
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