Omega-3 fatty acids are called essential fatty acids because they are needed for normal growth and development, but can only be supplied by diet. Omega-3 fatty acids can be found in mackerel, salmon, sardines, anchovies, and tuna or as extracted oils from flaxseed, canola, or soybeans.
Scientists studying the Eskimo people of Greenland in the 1970s noted that while their diet was very high in fat from eating whale, seal, and salmon, the Inuit suffered far less coronary heart disease than their European counterparts. The reason for this seems to .be that omega-3 fatty acids increase the concentrations of HDL ("good") cholesterol and may also produce a moderate decrease in total cholesterol level. Clinical studies have shown that people who consume fish and omega-3 fatty acids have a lower risk of heart attack and cardiac death (JAMA 2001; 285:304; JAMA 2002; 287:1815).
A good way to achieve this dietary requirement is by eating fatty fish two or three times a week and/or eating vegetables and oils containing omega-3 fatty acids. Women who are pregnant or breastfeeding should talk to their doctor before taking fish-oil supplements. People who take nonsteroidal anti-inflammatory drugs, warfarin, or other anti-clotting medications should also consult a physician before using these supplements.