Why Do We Need Essential Fatty Acids?
There are two major categories of fatty acids, primarily the omega-6 and the omega 3 fats. Most fatty acids can be made in the body except for two essential ones (has to come from the diet): Omega 6 linoleic acid (18 carbons) and omega-3 alpha-linolenic acid (18 carbons).
If adequate amounts of linoleic acid and alpha linolenic acid are not present in the diet, an essential fatty acids deficit can cause symptoms such as dry skin, liver abnormalities, poor healing of wounds, growth failure in infants, impaired vision and hearing.
The ratio of the omega-6 and 3 fatty acids is also important for health. This is because they are made into hormone-like molecules called eicosanoids. From omega-6 linoleic acid we make arachidonic acid. (AA). From omega-3 alpha linolenic acid we make eicosapentenoic acid (EPA) and docosahexaenoic acid (DHA). AA and EPA compete for the enzymes needed for eicosanoid synthesis, so the ratio becomes very important.
Food sources for AA are meat and eggs; we get EPA and DHA from fish oils.
What do the Eicosanoids Do for Health?
Eicosanoids help regulate blood clotting, blood pressure, immune function, and other body processes and can have opposite effects on health. For example, the eicosanoids derived from the omega-6 fatty acid, linoleic acid increases blood clotting whereas those derived from the omega-3 alpha linolenic acid decreases blood clotting. Omega-3 EPA and DHA have anti-inflammatory properties suggesting they are protective against heart disease while the omega-6 fatty acids tend to be more inflammatory that may increase the risks of rheumatoid arthritis, inflammatory bowel disease or cancer.
It is recommended that we have a balance of omega-6 to omeg 3- fatty acids in the diet. A healthy balance is a dietary ratio of linoleic acid to alpha-linolenic acid of 5:1 to 10:1. To provide this ratio, a diet that contains 20 grams of linoleic acid should also include 2-4 grams of alpha-linolenic acid.
The American diet contains plenty of linoleic acid, so to get a healthier mix of both, the diet should also contain an adequate intake from omega-3 foods such as fish, walnuts, flaxseed, and leafy green vegetables.