With nearly 70 percent of the U.S. population overweight, there’s little doubt that most Americans could stand to shed a few pounds. In their quest for weight loss, many folks turn to reduced-calorie diets that are low in fat.

According to neurologist David Perlmutter, founder of the Perlmutter Health Center in Naples, Fla., and author of “The Better Brain Book,” “Low-fat or no-fat diets aren’t always a good thing. When it comes to your health, it isn’t the quantity of fat in your diet that’s most important; it’s the type of fat.”

Saturated fats are the dietary bad guys, known to increase blood cholesterol levels and contribute to heart disease. Typically, saturated fats are derived from animal sources, including meat and dairy products.

Even more dangerous are the trans-fatty acids, commonly found in margarine, processed baked goods and fried foods; and in any food that lists “hydrogenated” oil as an ingredient. Diets rich in trans fats have been linked to a greater risk of heart disease, blood clotting disorders, and type 2 diabetes.

While saturated fats and trans-fatty acids can be hazardous to your health, omega-3 fatty acids provide a number of important benefits, especially for the heart and the brain. Of the three major types of omega-3 fatty acids in the human body, the one known as docosahexaenoic acid, or DHA for short, is the type found in the brain and heart, as well as in the eyes.

“DHA makes up 25 percent of the brain’s fat, so it plays an important structural role in the brain,” Perlmutter explained. “It is critical for brain health.”

Recent research demonstrated that low levels of DHA in the diet are associated with a higher risk of Alzheimer’s disease and other types of dementia. High dietary intake of DHA, on the other hand, has been linked to a reduced risk of these conditions.

“DHA lowers the risk of Alzheimer’s disease because it reduces the rate at which amyloid proteins are formed in the brain, and increases the rate at which they are cleared from the brain,” said Perlmutter.

Amyloid proteins are thought to be responsible for causing Alzheimer’s disease. The sticky substances accumulate in the brain, interfering with important functions like learning and memory.

“Alzheimer’s is a preventable disease, but it has no cure,” noted Perlmutter. “Increasing your intake of DHA is something simple you can do to help avoid it.”

DHA is also highly concentrated in the retina and the membranes of the eyes, and is necessary for optimal function of nerve cells involved in vision. Several studies have linked high DHA intake to a reduced risk of developing age-related macular degeneration, a major cause of blindness in elderly Americans.

A diet rich in DHA is also beneficial to cardiovascular health. The nutrient has been shown to lower triglycerides and total cholesterol levels, and increase levels of high-density lipoprotein, or “good” cholesterol.

Despite the importance of DHA, most Americans don’t get enough of this critical nutrient. The U.S. population has one of the lowest levels of DHA consumption in the world.

While the recommended intake is 250 milligrams (mg) per day, the average American consumes only about 100 mg per day. “Even when they have a nutritious diet, it’s still difficult for most Americans to get enough DHA from the foods that they eat,” Perlmutter noted.

In the diet, DHA is found primarily in fatty fish, something that many Americans don’t eat on a regular basis. “Earlier research suggested that we should increase our consumption of fish, but we know that this isn’t the best thing to do, because fish is a source of mercury and other toxins,” said Perlmutter.

Fortunately, there is an all-natural, non-fish alternative. A product called Martek DHA, produced by marine algae in a laboratory environment, is the only vegetarian source of DHA that provides a meaningful amount of the nutrient.

Although walnuts, flax seed, and certain vegetable oils are good vegetarian sources of some omega-three fatty acids, they aren’t a significant source of DHA. Unlike fish and fish oil supplements, Martek DHA is produced in a controlled atmosphere, so there is no risk of oceanic contamination.

Martek DHA is available for individuals of all ages in the form of dietary supplements, including one called Neuromins, which can be found at many health food stores. The nutrient may also be found in a few fortified foods.

“Now that the American diet is so deficient in so many nutrients, everyone should be taking a DHA supplement,” said Perlmutter.

Dr. Rallie McAllister is a family physician in Kingsport, Tenn.

Date: Oct 20, 2005

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