WEIL: Omega 3s losing race with omega 6s

By Dr. Weil, Special to the Rocky

Published December 25, 2007 at 12:05 a.m.

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I don't understand the difference between omega 3 and omega 6 fatty acids.

Omega 3 and omega 6 are types of essential fatty acids - meaning we can't make them on our own and have to obtain them from our diet. They're poly- unsaturated fatty acids that differ from each other in their chemical structure.

In modern diets, there are few sources of omega 3 fatty acids, mainly the fat of cold-water fish, such as salmon, sardines, herring, mackerel, black cod and bluefish.

There are two critical omega 3 fatty acids that the body needs, eicosapentaenoic acid (called EPA) and docosahexaenoic acid (or DHA). Vegetarian sources, such as walnuts and flaxseed, contain a precursor omega 3 (alpha-linolenic acid, called ALA) that the body must convert to EPA and DHA. EPA and DHA are the building blocks for hormones that control immune function, blood clotting and cell growth as well as components of cell membranes.

By contrast, sources of omega 6 fatty acids are numerous in modern diets. They're found in seeds and nuts and the oils extracted from them. Refined vegetable oils, such as soy oil, are used in most of the snack foods, cookies, crackers and sweets in the American diet, as well as in fast food. Soybean oil alone is so ubiquitous in fast foods and processed foods that an astounding 20 percent of the calories in the American diet are estimated to come from it.

The body also constructs hormones from omega 6 fatty acids. In general, hormones derived from the two classes of essential fatty acids have opposite effects. Those from omega 6 fatty acids tend to increase inflammation (an important component of the immune response), blood clotting and cell proliferation, while those from omega 3 fatty acids decrease those functions. The two families of hormones must be in balance to maintain optimum health.

Many nutrition experts believe that before we relied so heavily on processed foods, humans consumed omega 3 and omega 6 fatty acids in roughly equal amounts. But to our great detriment, most North Americans and Europeans now get far too much of the omega 6s and not enough of the omega 3s. This dietary imbalance may explain the rise of such diseases as asthma, coronary heart disease, many forms of cancer, autoimmunity and neurodegenerative diseases, all of which are believed to stem from inflammation in the body.

The imbalance between omega 3 and omega 6 fatty acids may also contribute to obesity, depression, dyslexia, hyperactivity and even a tendency toward violence.

Bringing the fats into proper proportion may relieve those conditions, says Joseph Hibbeln, M.D., a psychiatrist at the National Institutes of Health and perhaps the world's leading authority on the relationship between fat consumption and mental health. At the 2006 Nutrition and Health Conference sponsored by the University of Arizona's College of Medicine and Columbia University's College of Physicians and Surgeons, Hibbeln cited a study showing that violence in a British prison dropped by 37 percent after omega 3 oils and vitamins were added to the prisoners' diets.

If you follow my anti-inflammatory diet (available on my Web site), you should get a healthy ratio of these fatty acids. In general, however, you can cut down on omega 6 levels by reducing consumption of processed and fast foods and polyunsaturated vegetable oils (corn, sunflower, safflower and soy, for example). At home, use extra-virgin olive oil for cooking and in salad dressings. Eat more oily fish (or take fish-oil supplements), walnuts, freshly ground flaxseed and omega 3-fortified eggs. Your body and mind will thank you.

To ask Weil a question, visit his Web site, drweil.com, and click "Ask Dr. Weil" and then "Ask Your Question."

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