Febrary 21, 2005

Hello!

You may have heard about the health benefits of omega-3 fatty acids.

"Omega-3 fatty acids benefit the heart of healthy people, and those at high risk of -- or who have -- cardiovascular disease. We [the American Heart Association] recommend eating fish (particularly fatty fish) at least two times a week. Fish is a good source of protein and doesn't have the high saturated fat that fatty meat products do. Fatty fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are high in two kinds of omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ... We also recommend eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils. These contain alpha-linolenic acid (LNA), which can become omega-3 fatty acid in the body. The extent of this modification is modest and controversial, however."
http://www.americanheart.org/presenter.jhtml?identifier=4632

While omega-3 fatty acids come from many sources, fish seem to get the most attention -- and the most press.

"Press Release Date: April 22, 2004
Fish oil can help reduce deaths from heart disease, according to new evidence reports announced today by the Agency for Healthcare Research and Quality [AHRQ]. The
systematic reviews of the available literature found evidence that long chain omega-3 fatty acids, the beneficial component ingested by eating fish or taking a fish oil supplement, reduce heart attack and other problems related to heart and blood vessel disease in persons who already have these conditions, as well as their overall
risk of death. ... The review also found other evidence indicating that fish oil can help lower high blood pressure slightly, may reduce risk of coronary artery re-blockage
after angioplasty, may increase exercise capability among patients with clogged arteries, and may possibly reduce the risk of irregular heart beats -- particularly in
individuals with a recent heart attack. 'These findings will help health care professionals and the public understand which benefits of omega-3 fatty acids have been scientifically proven and pinpoint areas where additional evidence is needed,' said Carolyn M. Clancy, M.D., AHRQ's Director."
http://www.ahrq.gov/news/press/pr2004/omega3pr.htm

With all of the recommendations and positive attention that fish and omega-3 fatty acids have been receiving, one might get the impression that adding some omega-3s will cure all ailments.

"The quantity and strength of evidence for effects of omega-3 fatty acids on outcomes in the conditions assessed varies greatly. The findings of many studies among type II diabetics provide strong evidence that omega-3 fatty acids reduce serum triglycerides but have no effect on total cholesterol, HDL cholesterol, and LDL cholesterol. For rheumatoid arthritis, the available evidence suggests that omega-3 fatty acids reduce tender joint counts and may reduce requirements for corticosteroids, but does not support an effect of omega-3 fatty acids on other clinical outcomes. There are insufficient data available to draw conclusions about the effects of omega-3 fatty acids on inflammatory bowel disease, renal disease, SLE, bone density, or fractures or the effects of omega-3 fatty acids on insulin resistance among type II diabetics."
http://www.ahrq.gov/clinic/epcsums/o3lipidsum.htm

While omega-3 fatty acids do have important health benefits, getting them all from fish may have some risks.

"Last year the Food and Drug Administration determined there is so much mercury in the sea that women of childbearing age should severely limit their consumption of larger ocean fish. ... In adults, mercury poisoning can cause numbness, stumbling, dementia, and death. 'It's no secret that mercury exposure is highly toxic,' says toxicologist Alan Stern, a contributor to a 2000 National Research Council report on mercury toxicity. ... Data now suggest effects might occur at levels lower than anyone suspected. Some studies show that children who were exposed to tiny amounts of mercury in utero have slower reflexes, language deficits, and shortened attention spans. In adults, recent studies show a possible link between heart disease and mercury ingested from eating fish."
http://www.discover.com/issues/mar-05/features/our-preferred-poison/

Mercury is bad, but this does not mean that fish should be removed from everyone's diet.

"There are plenty of good reasons to eat fish: It's high in protein, low in unhealthy fat, and rich in healthful omega-3s. But recent reports have questioned the safety of eating fish, due to potentially unacceptable levels of PCBs and mercury. PCBs (polychlorinated biphenyls) and mercury are industrial pollutants that find their way into fresh waters and oceans where they are absorbed by fish. ... PCBs have been linked to a variety of health problems, but there is no official agreement that the amount of PCBs in farmed fish poses a health hazard. ... As for mercury, high levels may damage the developing nervous system. ... Adding plant foods that contain omega-3s to a diet that only has limited amounts of fatty fish is advantageous. Plant sources contain a shorter-chain fatty acid, called ALA (alpha-linolenic acid), that humans can convert to the type of omega-3s fish has, but it is not as effective as obtaining omega-3s from fish."
http://www.aicr.org/publications/newsletter.lasso?index=1769

With all that said, how can you know what is right for you.The recommendations are different for different groups. In general, guidelines suggest:
"* Continue eating a variety of fish, but limit your consumption of farmed salmon to two 3 oz. servings per week. Wild salmon is usually available frozen or canned.
* To reduce PCBs, remove skin and visible fat from fish. Bake, broil or grill fish instead of frying.
* Add plant foods that contain omega-3s."
http://www.aicr.org/publications/newsletter.lasso?index=1769

If you are concerned about eating too much fish, you can always,

"Add plant foods that contain omega-3s," but what if you are a vegetarian, and you don't eat fish at all? What sources of omega-3s are available to you?
"Plant Foods
* Flaxseed and flaxseed oil
* Canola oil
* Walnuts
* Soybeans
* Wheat germ
* Green leafy vegetables (including spinach, kale, leeks and broccoli)
* Dried beans (such as kidney, garbanzo and pinto)"
http://www.aicr.org/publications/newsletter.lasso?index=1769

Questions of the Week:
Why are omega-3 fatty acids an important part of a healthy diet? How are different sources better (or worse) for different people? How can you know what sources (and what quantities of those sources) are right for you? If you do eat fish, how can you balance the possible health benefits and the possible health risks? Which types of fish should you choose over others? Which should you avoid entirely? If you do not eat fish, what can you do to get the right amount of omega-3s for your body? Whether or not you eat fish, how can you balance a variety of sources in order to maximize the health benefits of the omega-3s your body is getting -- while, at the same time, minimize the risks and health hazards associated with some sources?