It's not just how much you eat that counts. Consuming fewer carbs and more "healthy" fats may help stave off chronic disease.
By John Casey
WebMD Weight Loss Clinic - Feature
Reviewed By Kathleen Zelman, MPH, RD, LD
The Food Guide Pyramid, the U.S. Department of Agriculture's map of what's supposed to make up a healthy diet, is familiar to everyone from schoolchildren to health-conscious senior citizens.
But recent research involving more than 100,000 people could turn the pyramid on its side.
The study found that people whose diets contained fewer carbohydrates--foods like bread and cereals--and a bigger proportion of "healthy" fats, such as olive oil, than recommended by the pyramid were 20% to 40% less likely to develop chronic disease than those whose diets more closely matched the USDA guidelines.
"The Food Pyramid is flawed," says study author Walter Willet, MD, a professor of nutrition at the Harvard University School of Public Health. "It says all fats are bad, all complex carbohydrates are good, all protein sources offer the same nutrition, and dairy should be eaten in high amounts."
More specifically, the Pyramid recommends eating the following every day:
- 6 to 11 servings of carbohydrates such as bread, cereal, rice, and pasta.
- 3 to 5 servings of vegetables.
- 2 to 4 servings of fruit.
- 2 to 3 servings of dairy (milk, yogurt, cheese).
- 2 to 3 servings of protein (meat, fish, eggs, poultry, dry beans, nuts).
- As few fats, oils, and sweets as possible.
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:
- Four times as much fish and poultry as red meat.
- Five servings of vegetables daily.
- Four servings of fruit daily.
- One daily serving of nuts, or vegetable protein like soy.
- More polyunsaturated fats (mostly found in vegetable sources) than saturated fats.(mostly found in animal sources)
- 15 grams of fiber from grain sources, like cereal or whole-wheat bread, each day.
- For women: ½ to 1½ alcoholic drinks a day.
- For men: 1½ to 2 ½ alcoholic drinks a day.
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%.
The USDA last changed the guidelines behind its food pyramid in 2000, and plans to do so again in 2005, says USDA spokesman John Webster.
Webster tells WebMD that the Harvard study's findings are interesting, but he adds that the recommendations in the Alternative Healthy Eating Index may be too stringent for most people to actually follow.
"In my opinion, it would be great if more of us could just take a step in the right direction for eating, rather than hope we can make the kinds of giant steps the AHEI is after."
Kitty Quinn, RD, LD, a dietitian at the Barnes-Jewish Hospital in St. Louis, Mo., agrees.
The researchers came up with "important findings and great guidelines," Quinn says. "But as a country, we aren't even following the Food Guide Pyramid as it is. We still eat too much meat, dairy products and sugar."
Quinn says that if the Food Pyramid were seen as Step 1 of a better nutrition program for the country, then the AHEI recommendations would be closer to a Step 10.
"I don't think the population is anywhere close to even eating at a Step 1 level, let alone 10," she says. "In my opinion, it would be great if more of us could just take a step in the right direction for eating, rather than hope we can make the kinds of giant steps the AHEI is after."
Where To Start?
Maybe so, but if you want to take a step in the right direction ? be it big or small ? what should you do first?
According to Willet, simply avoiding excess calories - no matter what foods they come from ? and getting at least a moderate amount of exercise should be your first goal.
Second on Willet's list comes avoiding trans fatty acids, which he says are worse for your arteries than lard.
"Trans fat not only increases levels of 'bad' cholesterol in the bloodstream, but it also decreases levels of 'good' cholesterol," he tells WebMD.
And third on his priority list? Well, let's say that sometimes there is a comfortingly old-fashioned feel to Willet's advice. He says we should enjoy healthy fats, like the liquid oils found in most plants, as well as the fats in nuts, seeds and some fish - all in moderation, of course.
"People also tend to replace fat in their diets with foods high in sugar or refined carbohydrates," he says. "A lot of people think that a plain bagel with jam can be a healthy thing to eat in the morning, but actually that is one of the unhealthiest duos you can eat because it has a high [blood sugar] load. You'd be better off with scrambled eggs cooked in corn oil or a whole-grain cereal."
Originally published Jan. 2, 2003.
SOURCES: American Journal of Clinical Nutrition, December 2002 * Walter Willet, MD; professor of nutrition, Harvard University School of Public Health, Boston * John Webster, spokesman, USDA * Kitty Quinn, RD, LD; dietitian, Barnes-Jewish Hospital. St. Louis, Mo.
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