July 25, 2002 -- Looking to lower your chances of developing diabetes? Switch from white bread to whole wheat, and don't pass up the popcorn. New research finds that whole grain foods may protect against the disease by improving a person's sensitivity to the hormone insulin.
"Whole grains appear to be beneficial with respect to insulin levels and potentially with respect to diabetes risk," says Tufts researcher Paul F. Jacques, whose study appears in the latest issue of the American Journal of Clinical Nutrition.
"We aren't really certain why whole grains affect insulin levels, but we suspect that there may be more than one reason," Jacques tells WebMD. "Whole grain foods are high in fiber and magnesium, and people who eat these foods may have generally healthier lifestyles."
Type 2 diabetes is usually caused by the body's failure to efficiently use the insulin it produces to break down sugar in our diet. This sugar, glucose, can build up in the blood, and the pancreas -- the gland that produces insulin -- may go into overdrive trying to produce enough. Thus, high blood insulin levels is indicative of diabetes and is one of several risk factors for diabetes. Others include obesity and high cholesterol levels.
Tufts University researchers evaluated whole grain food consumption and blood insulin levels in just under 3,000 people taking part in a large, ongoing study of disease risk factors. They found that those who reported eating the most servings of whole grain foods tended to have lower insulin levels, lower body weights, and lower cholesterol levels.
The study is just the latest to find that foods such as slow-cooking oatmeal, popcorn, brown rice, and certain processed whole grain breads and cereals are protective against type 2 diabetes. Eating whole grain foods has also been shown to lower the risk of cardiovascular disease.
The 2,941 study subjects provided blood samples and detailed information about their diets between the years 1991 and 1995. The average consumption of whole grains was eight servings per week, compared with 20 servings of foods made from white flour and other refined grains.
Nutrition researcher Frank Hu, of the Harvard School of Public Health, tells WebMD that the key to lowering type 2 diabetes risk is maintaining a healthy weight and eating a balanced diet that includes the right kinds of carbohydrates and fats.
Though consumption of refined grains was not found to be associated with an increase in insulin in this study, Hu said Americans still get far too many calories from processed products made from white flour and other refined grains.
"Most of the carbohydrates in our diets come from refined grains, and that is a problem," Hu tells WebMD. "Not all carbohydrates are the same, just like not all fats are the same. Whole grain foods are good carbohydrates, and most people don't eat enough of them."
Eleftheria Maratos-Flier, of Harvard's Joslin Diabetes Center, agrees. She says the wildly popular weight-loss programs that restrict or eliminate carbohydrates from the diet are delivering the false message that all carbohydrates are bad. Maratos-Flier is director of obesity research at Joslin.
"We are going from one simplistic message to another one," she says. "We were told that all fats are bad, and we now know that is not the case. And now we are hearing that carbohydrates are bad for you, without distinguishing between the carbohydrates in an ear of corn and those in white bread or white rice. That is way too simplistic."