What foods are good sources of essential fatty acids?
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Good sources of linoleic acid are safflower oil, sunflower seeds (oil roasted), pine nuts, sunflower oil, corn oil, soybean oil, pecans (oil roasted), Brazil nuts, cottonseed oil and sesame seed oil. Dietary surveys in the United States suggest that the intake of linoleic acid is about 12-17 grams for men and 9 to 11 grams for women. Good plant sources of alpha-linolenic acid are flaxseed, walnuts their oils are among the best sources of α-linolenic acid as are soybean, canola and linseed oil as well as some leafy vegetables. Diet surveys in the United States suggest that typical intakes of α-linolenic acid are about 1.2 to 1.6 grams daily for men and 0.9 to 1.1 grams daily for women. Therefore the ratio of linoleic acid to alpha-linolenic acid is about 10 to 1, which many nutritionists believe to be too high. |
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Marine mammals (e.g., whale, seal, and walrus) and the oil derived from cold-water fish (cod-liver, herring, menhaden, and salmon oils) provide eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are fatty acids that are made from linolenic acid in marine animals. A lot of interest in the omega-3 fatty acids was created when researchers reported that there is a lower incidence of heart disease in some populations (e.g. Greenland). Diet patterns showed high fish consumption in these people, which leads to greater omega-3 fatty acid intake and a reduced incidence of heart disease. In addition, there are links between the consumption of fish and cognitive development as well as reducing age related losses in memory and cognition. |
What foods contain trans fatty acids?
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Trans fatty acids can be found in many fat sources although its prevalence is very low. Bovine (cows, steer, oxen, etc) food sources are probably the greatest natural contributors of trans fatty acids to the human diet. For instance, beef, butter, and milk triglycerides may contain 2 to 8 percent of their fatty acids as trans fatty acids. Interestingly, cattle are not solely responsible for generating this trans fatty acid content. It is actually the bacteria in their unique stomachs that produce the trans fatty acid. These fatty acids are then absorbed by the cow and make their way into the tissues and milk of these animals. |
In addition, trans fatty acids can be created during the processing of oils (i.e., margarine and other hydrogenated oils) which will be described soon and as cooking oils are used over long periods for cooking, such as in restaurants like fast food restaurants and diners. In more recent decades, more than half of the trans fatty acids in the human diet were derived from processed oils either consumed plain or used in recipes (e.g. fried foods, baked snack foods). Cookies, crackers, and other snack foods that utilize hydrogenated vegetable oil may contain up to 9-10 percent of their fatty acids as trans fatty acids.
Because the consumption of higher amounts of trans fatty acids is linked to increased risk of heart disease and stroke the American Heart Association as part of the more recent Dietary Reference Intakes (DRIs) in the United States and Canada recommend limiting the trans fat level of the diet. In addition, food manufacturers in many countries including the United States and Canada are required to list the trans fat levels on the Nutrition Facts on food labels. Because of this snack food manufacturers are choosing hydrogenated oils with lower trans fat content to produce snack foods. Furthermore, in 2006 New York City placed a ban on trans fat in restaurants, a public health initiative that is being followed by other cities.
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