Redefining a Healthy Diet
Harvard researchers offer revisions to U.S. dietary guidelines
THURSDAY, Nov. 21, 2002 (HealthDayNews) -- A few simple changes to the federal government's "Dietary Guidelines for Americans" could further reduce the risk of major chronic diseases, Harvard University researchers say.
The trouble with the guidelines is that they don't make a distinction between different types of fat or protein; they lump red meat, chicken and nuts together as sources of protein; and they place too much emphasis on carbohydrates, the researchers say.
A 15-year study showed that men who ate white meat instead of red, unsaturated rather than saturated fat, and whole grains rather than refined grains lowered their risk of major chronic diseases by 20 percent. The reduction for women was 11 percent, says a report by the researchers in the new issue of the American Journal of Clinical Nutrition.
Marjorie McCullough, a nutritional epidemiologist who was part of the Harvard University School of Public Health team that looked at the U.S. Department of Agriculture dietary guidelines with a critical eye, says the recommended changes were prompted by a closer look at specific parts of the guidelines.
For example, the USDA guidelines emphasize lowering intake of all sorts of fats.
"We agree with that in general, but we look at a higher ratio of polyunsaturated fat to saturated fat," says McCullough, who now is a nutritional epidemiologist with the American Cancer Society. That means consuming more liquid vegetable oil and fish oil, she says. The Harvard guidelines -- dubbed the Alternative Healthy Eating Index -- also recommend lower intake of total trans fats, which come from margarine and vegetable shortening.
Potatoes are out because people generally consume them in the form of French fries. Baked potatoes are OK, McCullough says, but "they don't have the same benefit of risk reduction as other vegetables do, such as broccoli."
Four servings of fruit daily, 15 grams a day of cereal fiber, one serving a day of nuts and soy protein, moderate alcohol consumption -- one or two drinks a day -- and multivitamin supplements are also recommended.
These recommendations are not based on any abstract laboratory study. Instead, the Harvard team had more than 150,000 men and women enrolled in the "Health Professionals Follow-Up Study" and the "Nurses Health Study" give detailed lists of what they were eating, and then looked at the diseases they got over a 15-year period.
The men whose diet most closely followed the Harvard recommendations cut their risk of cardiovascular disease by 39 percent, compared to those whose diets strayed farthest from the guidelines. For women, the reduction was 28 percent. By comparison, the reduction for those who followed the federal dietary guidelines was 11 percent for men and 3 percent for women. No reduction of cancer risk was found for either set of guidelines.
A U.S. Department of Agriculture spokesperson says the federal dietary guidelines are coming up for review and possible revision. The review will be done in collaboration with the U.S. Department of Health and Human Services. A notice requesting nominations for a committee to do the review will be placed in the Federal Register, possibly as early as next month, according to the spokesperson.
What To Do
The current federal dietary guidelines are available from the U.S. Department of Agriculture. The National Cancer Institute offers a program to help you eat five servings of fruits and vegetables a day.