By Katherine Tallmadge
Wednesday, March 24, 2004; Page F01
I first became interested in the power of omega-3 fatty acids when psychiatrists I work with began prescribing them for their depressed patients. Then I started hearing about their benefits for arthritis and a host of other diseases. And I couldn't help but wonder, could it be possible that one simple change in the diet could provide so many benefits?
The connection between omega-3 fatty acids and health was first observed in the 1970s. Scientists noted that compared with their counterparts in Scandinavia, Greenland Eskimos had a reduced rate of heart disease, rheumatoid arthritis and other conditions even though they were eating a high-fat diet. The scientists hypothesized that the type of fat -- marine derived -- might play a role.
Since then, study after study has confirmed that omega-3 fatty acids, a type of polyunsaturated fat found primarily in fish, have a potent and positive effect on heart disease patients. Omega-3s prevent irregular heart beat, reduce plaque inside artery walls and decrease blood clotting, triglycerides (blood fat), blood pressure and inflammation.
"Omega-3s favorably affect a number of risk factors for cardiovascular disease and at the top of the list is reducing the risk of sudden death from heart attack," says Penny Kris-Etherton, a nutrition professor at Pennsylvania State University.
But the healing powers of omega-3s don't stop there. Research suggests they may reduce the risk of diabetes, reduce insulin resistance in people with diabetes, enhance bone density and inhibit proliferation of cancer cells in the breast, prostate and colon and improve skin condition by curbing psoriasis. Inflammatory diseases such as rheumatoid arthritis, ulcerative colitis and Crohn's disease seem to improve with more omega-3s. In infants, it improves cognition and visual acuity. And emerging research indicates omega-3s may boost levels of the brain chemicals serotonin and dopamine, decreasing depression and violent behavior.
While not an answer to every ailment, omega-3 fatty acids possess considerable healing powers. As an indication of their importance, the Food and Nutrition Board of the National Academy of Sciences recently established a minimum daily requirement: 1.1 grams for adult women, 1.6 grams for adult men.
But in nutrition, balance is everything. There is another essential fatty acid, omega-6. Each type of fatty acid has its important functions. But if the level of one of the fatty acids is too high, it competes with and interferes with the functioning of the other.
"If you eat too much omega-6, as is the case with today's American diet, this interferes with omega-3 action, promotes inflammation, blood clotting and constricts blood vessels, and causes a huge array of diseases," says Joseph Hibbeln, a psychiatrist at the National Institutes for Alcohol Abuse and Alcoholism.
However, the ideal ratio of omega-6 to omega-3 is a source of heated debate among researchers. If you followed the fatty acid recommendations of the National Academy of Sciences, your ratio would be 11 to 1. But many omega-3 researchers say a far lower ratio is ideal for optimal health. Still other researchers believe a specific ratio doesn't matter but the amount of omega-6 and omega-3 you're eating is important.
What all the scientists do agree on is the need to consume more omega-3s. Americans don't come close to getting their omega-3 requirement. But we used to.
"Early humans ate plenty of high-omega-3 foods, wild greens, seafood, lean animals that grazed on high-omega-3 grasses, such as purslane, and our bodies evolved a need for it," says Artemis Simopoulos, president of the Center for Genetics, Nutrition and Health and author of "The Omega Diet" (Harper Collins, 1999).
Today, the highest concentration of omega-3s is found in fish. The two most potent omega-3 fatty acids are known as DHA and EPA and are usually found in oily fishes, such as mackerel, salmon and tuna. These fatty acids end up in every single cell membrane in the human body. They act as a cell lubricant, improve flexibility and communication among cells.
Omega-3s are also found in plant sources, especially flaxseed oil, canola oil, walnuts and some vegetables. These fatty acids, while valuable, are not as beneficial as the more potent omega-3s found in fish.
But for those who are concerned about the discovery of mercury and other contaminants in seafood, plant sources are important to consider. These omega-3s occur as ALA, a type of fatty acid that must be converted in the body to the more usable forms of DHA and EPA.
Omega-6s are found in safflower, soybean and corn oil, which are in many processed foods. Because of Americans' increased intake of processed and fast foods over the past 50 years, omega-6s have largely replaced omega-3s in the modern diet.
Though grass-fed animal meat, available in some stores and farmers markets, contains at least two times more omega-3s than grain-fed animal meat, it doesn't come close to the levels you can find in fish. Animal scientists are working on improving the omega-3 fatty acid content of beef, chicken and other meats by feeding the animals flax and other high-omega-3 foods, but these products are a long way from being sold in your grocery store.
You can now buy omega-3-enhanced eggs from chickens that are fed algae, flax and/or fish. The reported amount of omega-3s contained in each egg, however, varies according to brand. These amounts of omega-3s are still considerably lower than levels found in fish.
Omega-3 supplements can be effective, though it is possible to take too much. For example, by reducing inflammation, omega-3s also may reduce the immune response. There is also a slight increased risk for hemorrhagic stroke or excessive bleeding. Large doses should be taken only under a doctor's supervision.
How much fish do you need to consume? Most of the studies on omega-3s found a positive benefit with 500 to 1,000 milligrams per day. In response, the American Heart Association now recommends all adults eat a variety of fish, particularly oily fish, at least twice weekly (three-ounce portions), which would provide an average of 500 milligrams per day. For patients with coronary artery disease, the AHA recommends 1,000 milligrams daily -- but never above 3,000 milligrams.
As usual, balance is paramount.
Katherine Tallmadge is a washington nutritionist and author of "Diet Simple" (Lifeline Press, 2002). Send e-mails to her at email@example.com.
© 2004 The Washington Post Company