ACSM'S Health & Fitness Journal:
Departments: Fitness Focus Copy-and-Share
Thompson, Dixie L. Ph.D., FACSM
Dixie L. Thompson, Ph.D., FACSM, is the director of the Center for Physical Activity and Health and professor in the Department of Exercise, Sport, and Leisure Studies at the University of Tennessee, Knoxville.
A great deal of the media attention about dietary fats focuses on the avoidance of unhealthy saturated and trans fats. Although minimizing the intake of these fats is certainly important for good health, the Dietary Guidelines for Americans recommend that 20% to 35% of an adult's diet be composed of fats. That may leave people with the question-what are the good sources of dietary fats? Researchers are continuing to gather evidence about the impact of various types of fats on health, but it is clear that consumption of omega-3 fatty acids are linked with positive health outcomes.
Symbol What Are Omega-3 Fatty Acids?
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All fats are composed of hydrogen, carbon, and oxygen atoms. The arrangement of these atoms determines the type of fat. For example, in saturated fatty acids, carbon atoms are joined by bonds that allow the maximum number of hydrogen atoms to be attached; however, in unsaturated fatty acids, at least two of the carbon atoms are joined together in a way (i.e., double bonds) that limits the presence of hydrogen. Polyunsaturated fatty acids have multiple double bonds limiting the presence of hydrogen. Omega-3 fatty acids are polyunsaturated fatty acids. Omega-3 fatty acids can come from either animal (e.g., fish, shellfish, and organ meats) or plant (e.g., green leafy vegetables, nuts, canola oil, and flaxseed) sources. Omega-3 fatty acid supplements also can be purchased over the counter.
Symbol Omega-3 Fatty Acids and Heart Disease
Early evidence that omega-3 fatty acids might be important for heart health came from the observation that people who routinely consumed a lot of fish (e.g., Eskimos) were less likely to die early from cardiovascular disease. Subsequent studies that focused on consumption of fish, fish oils, and omega-3 fatty acids have reported less cardiovascular disease among those with the highest intake. Studies on animals suggest that omega-3 fatty acids are important for maintaining normal rhythmic function of the heart. In addition, when people consume increased amounts of omega-3 fatty acids, their blood levels of triglycerides go down, thereby reducing cardiovascular risk. There is even some evidence that omega-3 fatty acid consumption can help control blood pressure.
Symbol Omega-3 Fatty Acids and Other Diseases
Some have speculated that because omega-3 fatty acids serve as a source of substances needed for the body's inflammation processes, these fatty acids may be important in treating or preventing diseases linked with inflammation (e.g., asthma and arthritis). Research suggests that increased omega-3 fatty acid consumption reduces joint pain for people with rheumatoid arthritis. However, there is no substantial evidence that consumption of omega-3 fatty acids is beneficial for treating or preventing asthma, inflammatory bowel disease, or lupus. Recognizing the fact that omega-3 fatty acids are found in the brain and nerves, researchers also have searched for a link between these substances and neurological function. To this point, there is no conclusive evidence that consumption of omega-3 fatty acids is linked with cognitive function in aging, Alzheimer disease, or Parkinson disease.
Fats are an important part of a person's daily food intake. Fats serve as an important source of energy and provide the precursors for the formation of cell membranes and steroid hormones. However, to promote optimal health, one should choose healthy dietary fats. Evidence suggests that choosing omega-3 fatty acids as a part of one's diet will promote good health.