The body needs omega-3’s but can’t produce them on its own. Omega-3 fatty acids, a type of polyunsaturated fatty acids, must come from the diet. The best known sources are fish, shellfish, fish oils and organ meats (mmm … organ meats). The nutrients naturally occurring in leafy greens, nuts and flaxseed also provide the fatty acids we need. The body converts these foods into hormone-like biochemicals it uses for crucial functions including cell growth, brain development, muscle activity, blood clotting, fighting infection and even managing stress. Fish oils help fight heart disease, America’s No. 1 killer. Though further research is needed to confirm the positive effects of omega-3’s on many conditions (including asthma, arthritis, multiple sclerosis and diabetes), we have substantial evidence that they help fight cardiovascular disease. Fatty acids can reduce levels of triglycerides, which is a fat in the blood believed to contribute to heart disease. Fish oil in particular also helps lower high-blood pressure, improve coronary blood flow and reduce irregular heartbeats (especially in people who have already suffered a heart attack). Pregnant women face conflicting advice about fish. A recent study at the National Institutes of Health (NIH) drew dramatic conclusions regarding pregnant women and omega-3’s. Using data spanning 15 years, it suggested that increased intake led to higher IQ scores, better hand-eye coordination and more positive social interaction in their children. But the NIH has also warned pregnant and nursing women against consuming too much fish, since elevated mercury levels in the mother have been associated with reduced cognitive development in their children. So what’s a mother to do? Eat fish known to have lower mercury contamination or use fish oil supplements.(Sample mercury levels in various types of fish can be reviewed here.) Omega-3’s may play a role in mental health. According to studies by Dr. Joseph Hibbeln of the NIH, instances of depression in the U.S. have increased over the last century as our consumption of omega-3’s has declined. By contrast, countries with greater seafood consumption have lower rates of depression, suicide and homicide. Other research by Hibbeln has indicated that increasing omega-3 intake reduced anger levels in violent alcoholics and helped control mood swings in people with bipolar disorder. Different types of fatty acids compete for your health. Beyond consuming too few omega-3’s, Americans eat copious amounts of foods that actually interfere with the benefits of omega-3’s. Vegetable oils and meat are sources of omega-6 fatty acids, which compete with the functioning of omega-3 fatty acids. Due in large part to our love affair with processed food, which is made with vegetable oils, the typical American diet contains 10 times more omega-6 than omega-3. We’re taking a lesson on diet from the Eskimos. The interest in omega-3’s is based on studies from the 1970s, when it was discovered that Eskimos—whose diets include a lot of fish—had low mortality rates from cardiovascular disease. Researchers continue to learn by comparing the diets and relative health of various cultures.