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When fats are out of whack, our health can suffer

January 08, 2007|Susan Bowerman | Special to The Times

With each year, the nutritional story of fat seems to become more complicated.

It used to be fairly simple: Saturated fats were the bad guys, polyunsaturated fats were the good guys. Then came the trans fat revelation.

Here's another head-scratching twist: an ideal ratio of fats. Many nutritionists are concerned that our consumption of two kinds of polyunsaturated fatty acids -- the omega-3 and omega-6 fats -- is way out of balance these days and that our health may be paying the price.

Neither one is "bad" -- in fact, both linoleic acid (an omega-6 fat) and alpha-linolenic acid (an omega-3 fat) are termed essential -- you need to eat them because your body can't manufacture them. Though needed only in small amounts, they serve important functions as components of cell membranes, and they support healthful brain function, vision and growth.

But balance is important. When omega-6 fatty acids are metabolized, substances called eicosanoids are produced -- chemical messengers that promote inflammation and can affect virtually every system in the body. In acute injury or illness, pro-inflammatory eicosanoids are a necessary signal to the body to start the healing process.

Omega-3 fats result in the production of eicosanoids too, but these tend to have opposing, anti-inflammatory effects.

Trouble comes when an abundance of omega-6 compared with omega-3 is available from the diet, leading to the production of too many pro-inflammatory eicosanoids -- and a state of chronic, low-grade inflammation. Left unchecked, damage can occur to DNA, organs and tissues, contributing to common ailments such as heart disease and cancer.

And that is exactly what has been happening with our modern-day diet. It has been estimated that during our long evolutionary history, the plant-rich diet of ancient humans provided a healthful 1 to 1 ratio of these two fatty acids. But our food supply has changed so much in the last 150 years or so that it's estimated we now eat 14 to 16 times as many omega-6 as omega-3 fats, throwing the ideal balance of 1 to 1 well out of whack.

Nowadays, our main food sources of omega-3 fats are fish, with smaller amounts coming from walnuts, fruits, vegetables and flaxseed. We eat too few of these and too many fried foods, chips, dressings, spreads and sweets made primarily with omega-6-rich corn oil.

Humans are not the only ones consuming too many of these pro-inflammatory fatty acids. Cattle are natural herbivores that prefer grazing on omega-3 rich grasses. But they are fattened for the table on corn -- a food they wouldn't normally eat -- which ups the omega-6 fatty acids in the steak on your plate. (Grass-fed beef has an omega-6-omega-3 ratio of about 2 to 1 versus at least 4 to 1 for corn-fed beef.)

Although wild fish eat algae and other fish -- both excellent sources of omega-3 fatty acids -- most farmed salmon are fed salmon-chow rich in omega-6. So although farmed salmon is fattier than its ocean-caught counterpart, it carries a lot more omega-6 in its spare tire.

Chickens eating a natural diet of greens and insects produce eggs with more omega-3 fats than commercially raised birds fed corn and soy.

In spite of these modern-day challenges, you can adjust your omega-6-omega-3 ratio. To up your intake of omega-3 fats, try to eat at least three fish meals a week. Canned salmon, for example, is ocean-caught and is an inexpensive and convenient way to eat healthful omega-3 fats. If you don't like fish or can't eat it often enough, ask your healthcare provider if you should consider a fish oil supplement. If you eat red meat, try lean cuts of grass-fed beef.

Fill your plate with fresh fruits and vegetables, which provide a naturally healthful balance of fatty acids. Toss nuts into a salad for flavor, or dress it lightly with lemon and walnut oil. Eat berries, kiwi and pomegranate to get the beneficial balance of fats in their edible seeds.

The food industry has jumped on the omega-3 bandwagon, pumping a host of omega-3-fortified food products into the marketplace. Though this could, theoretically, help tip the balance of fats a bit more favorably, consider what else you are consuming along with the healthful fat. That omega-3-laced ice cream or margarine still has calories and lacks a host of nutrients that are contained in foods naturally rich in omega-3.

Most importantly, aim to reduce your overall fat intake from fried foods, sauces, dressings and baked goods which are usually rich in omega-6 fats. In doing so, you'll save calories -- which you can spend more wisely on more healthful fare and improve the overall quality of your diet.

Susan Bowerman is a registered dietitian and assistant director of the UCLA Center for Human Nutrition.

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