Food Pyramid Reshaping: New Dietary Guidelines (cont.)
The USDA is responsible not only for the Food Pyramid, but for the guidelines behind it. The agency uses a tool called the Healthy Eating Index or HEI, to measure how closely people's diets follow its dietary guidelines.
"The pyramid guidelines are changed by the USDA every five years," Willet tells WebMD. "But the pyramid has never been revised. Can the USDA actually do a meaningful revision of it without being influenced by meat and dairy lobbying groups? That's the big question."
So the Harvard researchers set out to develop an Alternative Healthy Eating Index (AHEI) based ion scientific evidence. They looked at the diets of more than 100,000 men and women enrolled in two other major studies, the Health Professionals Follow-up Study, and the Nurses' Health study. The subjects chosen for the Harvard study filled out questionnaires that allowed the researchers to plot what kinds of foods they were eating.
The researchers came up with their AHEI by looking at dietary patterns and eating behaviors that, according to the findings of earlier studies, were associated with lower rates of chronic disease, Willet says. Unlike the UDSA index, the AHEI emphasizes the quality of food choices ? such as white meat over red meat; whole grains over refined grains; oils high in unsaturated fat, such as many vegetable oils, over ones with saturated fat; and multivitamin use.
In the Harvard study, men whose diets most closely matched the AHEI were found to have lowered their overall risk of major chronic disease by 20%, and women by 11%, compared with those whose diets least closely followed these guidelines. In fact, the researchers found that men and women who followed the AHEI lowered their risk of cardiovascular disease by 39% and 28%, respectively.
Here are some of the high points of the diet that the researchers found to be associated with low rates of disease. The AHEI suggests eating:
The study did not establish daily amounts for all food groups, and it did not look at exercise.
But Can We Really Eat This Way?
The USDA is now reassessing its dietary guidelines to try to bring them in line with current nutrition recommendations, including the Dietary Reference Intakes issued last fall by another prestigious group of experts at the National Institute of Medicine. Those recommendations call for adults to get an hour of physical activity daily and eat fewer trans fatty acids (found in margarine, fast food, and commercially prepared baked goods). They also set a new upper limit for fat consumption: 35% percent of daily calories, up from 30%.