We are often told that omega-3 fatty acids are good for us and that omega-6 fatty acids are bad. But what is the real difference between omega-3's and omega-6's.
Both omega-3's and omega-6's are essential to human health. Both omega-3 fatty acids and omega-6 fatty acids are essential. This means that our bodies cannot make them on their own and that we have to obtain them from diet. Both kinds of essential fatty acids are polyunsaturated fats, differing by the location of the last double-bonded carbon in the chain of carbon atoms making up the "backbone" of the fat molecule.
The problem is getting the right balance of the two kinds of essential fats. Modern diets provide relatively little omega-3 fat and relatively abundant omega-6 fat. Most of the omega-3 fat we consume is found in fatty, cold water fish, such as sardines, salmon, mackerel, herring, black cod, tuna, hoki, and bluefish. If you don't consume a lot of fish, you don't get a lot of omega-3 fat in your diet.
Omega-6 fats are abundant in plant oils, including flaxseed oil, which is the famous source of the omega-3 fatty acid alpha-linolenic acid (ALA). We get lots of plant oils in fried foods, fast foods, bakery goods, chips, dips, and even in processed meats, fruits, and vegetables. Although it is possible to be deficient in omega-6 fatty acids, this has been rare in the developed world since the end of World War II.
The food Americans don't even know they eat that contributes 20 per cent of the calories in their diet. Most North Americans get about 20 per cent of their total calories from a single high omega-6 food, soybean oil. This abundant, inexpensive oil is used to fry chips, make cookies and cakes, and to add color and flavors even to "diet" foods.
The body uses omega-6 fats to make the hormones that activate the immune system and protect against bleeding. The body uses omega-3 fats to make the hormones that regulate the omega-6 hormones. All of the processes that use these essential fatty acids depend on an enzyme called a delta-6-desaturase. This enzyme works on omega-3 fats first, omega-6 fats second, and then, if there is a deficiency of essential fatty acids, on the omega-9 fatty acids (which are not essential) that are found in most fatty foods.
How fat keeps you from making fat-if you aren't eating too much! The action of the desaturase enzyme explains how taking omega-3 fatty acids helps your body avoid fat storage. Even on a day when you carefully following a low-calorie diet, there will be short times your body is storing fat rather than burning fat. Keeping the desaturase enzyme occupied with the making of hormones from omega-3 fatty acids means it is not available to help store omega-9 fat in your fat cells.
And if you have other problems that keep fatty acids locked in fat cells that store them, such as insulin resistance, your body is more likely to burn these fats rather than store them, giving you just a little boost on your way to weight loss by dieting. You do have to diet for this to work!
Turning back the clock to a time of good nutrition. Before the advent of processed foods, most people got about the right balance of omega-3's and omega-6's from their diets. The body functions well when these are consumed in a ratio of 1 to 1 up to about 1 to 6. The problem is, especially with the addition of soy oil to so many prepared foods, most people get about 20 times as much omega-6 fat as omega-3 fat. This helps the body make lots of pro-inflammatory hormones that cause high blood pressure, hardening of the arteries, joint inflammation, and brain diseases, but not nearly enough of the hormones needed to control them. The result is the rise of asthma, coronary artery disease, arthritis, cancer, depression, dyslexia, and uncontrollable violence, diseases which were once almost unknown.
Getting more omega-3's can benefit health in ways you'd never expect. Restoring the right balance of omega-3 and omega-6 fat in the diet can have profound effects. Dr. Joseph Hibbeln, a psychiatrist at the National Institutes of Health, found that giving prison inmates omega-3's cut rates of violence in the prison by 37 per cent. Studies have found that pregnant women who consume the essential fatty acid that is particularly abundant in fish oil, DHA (decosahexaenoic acid), have babies who grow up to be more athletic and to have greater verbal skills.
If you can't eat fish every day, take fish oil supplements. Reduce your consumption of processed foods, and avoid overeating in general. You'll feel better, and you have a much greater chance of avoiding long-term deterioration of your good health.
- Lane MD, Ntambi JM, Kaestner KH, Kelly Jr TJ (1989). "Differentiation-induced gene expression in 3T3-L1 preadipocytes. A second differentially expressed gene encoding stearoyl-CoA desaturase". J. Biol. Chem. 264 (25): 14755-14761.
- Nakamura MT, Nara TY (2004). "Structure, function and dietary regulation of 6, 5 and 9 desaturases". Annual Review of Nutrition 24 (24): 345-76.