Journal Name:
Exp. Biol. Med.
Article Title:
The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases
Date Written:
2008
Volume:
233
Number:
6
Page:
674
Author(s):
Simopoulos, A.P.
Article:
In this review article, the author makes a strong argument that humans today live in a nutritional environment that differs from that programmed in our genes. Studies on the evolutionary aspects of diet indicate that major changes have taken place in the diet, particularly in the type and amount of essential fatty acids and in the antioxidant content of foods. Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in many Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established.
Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today's Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a lower omega-6/omega-3 ratio), exert suppressive effects. Increased dietary intake of the omega 6 fatty acid – linoleic (LA) leads to oxidation of LDL, platelet aggregation, and interferes with the incorporation of the omega 3 long chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in cell membrane phospholipids.
Both omega-6 and omega-3 fatty acids influence gene expression. Linolenic acid, EPA and DHA have the most potent anti-inflammatory effects. Inflammation is at the base of many chronic diseases, including coronary heart disease, diabetes, arthritis, cancer, osteoporosis, mental health, dry eye disease and age-related macular degeneration.
In the secondary prevention of cardiovascular disease, a ratio of 4/1 was associated with a 70% decrease in total mortality. A ratio of 2.5/1 reduced rectal cell proliferation in patients with colorectal cancer, whereas a ratio of 4/1 with the same amount of omega-3 PUFA had no effect. The lower omega-6/omega-3 ratio in women with breast cancer was associated with decreased risk. A ratio of 2-3/1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5/1 had a beneficial effect on patients with asthma, whereas a ratio of 10/1 had adverse consequences. The optimal EFA ratio appears to differ with the disease under consideration. This is consistent with the fact that chronic diseases are multigenic and multifactorial.
The author surmises that the therapeutic dose of omega-3 fatty acids will depend on the degree of severity of disease resulting from the genetic predisposition. Numerous data indicate that a lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies, as well as in the developing countries.
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