What You Need To Know About Fish Oil

　　Americans spend billions on foods and supplements containing omega-3 fatty acids. Not all of it is money well spent.
　　Fifty years ago, two Danish epidemiologists pondered why Greenland's native Inuit could have a very low rate of heart attacks despite eating a high-fat diet full of whale and seal meat. They cobbled together $6,000, flew to Greenland and collected blood samples from 130 Inuit.
　　The Greenlanders' cholesterol numbers were good but not enough to explain the healthy hearts. Back in the lab the Danish researchers used an old gas chromatograph to study the samples, and found chemicals that they had never heard of before called omega-3 fatty acids. The chemicals, they argued, might explain the heart protective effect of the fish oil.
　　Today, omega-3 fatty acids have become a multibillion-dollar business. Americans spend $2.6 billion on nutritional supplements and foods fortified with omega-3 fatty acids. There's even an expensive prescription version of fish oil.
　　But not all of this is money well spent.
　　Decades of research back up the claim that the types of omega-3s found in fish oil, called EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), protect the hearts of people who already have cardiovascular disease. Fish oil may also have benefits in healthier people at high risk of developing heart disease.
　　But many of the foods you find at the supermarket are supplemented instead with alpha-linoleic acid (ALA), the type of omega-3 found in nuts and flax seeds. Cardiologists believe it does not have the same benefits, because the body does a poor job at converting ALA to EPA. “There may be differences in effectiveness,” says James Stein, head of preventive cardiology at the University of Wisconsin Medical School. So if you are buying a supplement for the heart benefits, make sure it contains EPA or DHA and not ALA.
　　Omega-3 fatty acids, found in oily fish such as salmon, herring, sardines and trout now get plenty of press for all sorts of benefits beyond protecting against heart disease, including fostering brain and eye development in kids and helping ease depression. One study indicated they may spare young people with signs of mental illness from developing full-blown schizophrenia.
　　"We in the West are just not eating enough omega-3s," says William Harris, a University of South Dakota nutritionist who is one of the leading experts on these fats. He notes two of three big clinical trials of fish oil show a reduction in deaths. "That's what sets omega-3s apart" from numerous other hyped vitamin supplements.
　　Omega-3s' benefits are mainly proven in heart disease, where big clinical trials have shown that lots of fish or doses of fish oil supplements can help people who already have heart disease. In patients with heart disease, trials have found that fish oil pills can modestly decrease a person's chances of dying. The fats may act as a mild blood thinner, and may even reduce the risk of sudden cardiac arrest by improving the electrical conductivity of heart cells.
　　A 1989 study of 2,000 men who had just had heart attacks found that those assigned to eat a lot of fish or take fish oil pills were 30% less likely to die during two years of treatment. A 19,000-patient study in Japan found that purified EPA fish oil pills reduced major heart problems by 19% in heart patients already taking cholesterol-lowering statins like Lipitor and Zocor.
　　The benefits in healthy people are murkier. But epidemiology studies indicate that fish oil may protect the hearts of healthy people as well. The American Heart Association recommends that healthy people eat oily, omega-3 containing fish twice a week. It recommends that patients with heart disease get a gram of the oil from fish or supplements each day.