Most of the time diabetics hear about the foods they can't eat, but a new study by Center for Human Nutrition researchers is shining a spotlight on foods they should eat. Leading this list of "goods" foods are those with a high fiber content.

A high intake of dietary fiber, mostly from fruits and vegetables, lowers blood glucose levels in diabetics, the UT Southwestern researches reported in the New England Journal of Medicine.

Dr. Abhimanyu Garg, senior investigator in the nutrition center and a professor of internal medicine, and Dr. Manisha Chandalia, assistant professor of internal medicine, said study participants who included 50 grams of fiber in their daily diet--about twice as much as the American Diabetes Association (ADA) recommends--lowered their glucose levels by 10 percent. The average American consumes about 17 grams of fiber per day.

The high-fiber diet also decreased insulin levels in the blood and lowered lipid concentrations in study participants with type II diabetes, or non-insulin dependent diabetes mellitus, the most prevalent type of diabetes.Dr. Garg, principal author of the article, said the results of the study should encourage diabetics to pay more attention to the fiber content of the foods they eat.

"Diet is the mainstay of diabetes treatment but is often neglected," Dr. Garg said. "The study supports the view that diet can improve glucose and lipid levels and thus reduce the risk of long-term diabetic complications."

The diets were specially prepared, and the fiber content of the high-fiber diet was achieved by incorporating foods naturally rich in fiber, particularly water-soluble fiber, the kind found in fruits, oats, barley and legumes. Fiber supplements were not used.

Fiber is classified according to water solubility. Most foods, such as fruits, vegetables and grains, contain both types of fiber.

Foods provided to the patients included cantaloupe, grapefruit, oranges, papayas, raisins, beans, okra, sweet potatoes, winter, and zucchini squash, granola, oat bran and oatmeal.

Thirteen patients, 12 men and one woman, were used in the study that took place at the National Institutes of Health-supported General Clinical Research Center at UT Southwestern.

Each patient ate the high-fiber diet and the moderate-fiber diet recommended by the ADA for six weeks, then switched to the other diet for six weeks. Both diets contained the same number and proportion of calories from carbohydrates, fats and proteins. Blood tests were done during the final week of each diet.

The ADA diet had 24 grams of fiber (8 grams of soluble fiber and 16 grams of insoluble fiber), while the high-fiber diet had 50 grams of fiber (25 grams each of soluble and insoluble fiber).

Three patients were treated with diet alone, and the other 10 were treated daily with 2.5 to 20 milligrams of glyburide--a medication used to treat diabetes--in addition to the diets. The glyburide dose remained constant throughout the study.

On the basis of previous studies conducted by Dr. Garg, the 2000 ADA diet supports diets rich in monounsaturated fats, such as those consumed in Mediterranean countries. The current study supports a less-emphasized aspect of the Mediterranean diet--fruits, vegetables and grains.

The study was funded by grants from the National Institute of Health and the Ministry for Education, Research, Science and Technology in Germany.