•  Diabetes Center

If a poor diet can help usher in Type 2 diabetes, here's some good news: a healthy high-fiber diet can help keep it under control.

In the last few years researchers have gotten a fix on what role specific foods might play in the development of Type 2 diabetes. A six-year study reported in the Journal of the American Medical Association in February 1997 found that women who ate a high-sugar, low-fiber diet -- including soft drinks, white bread, white rice, and mashed potatoes - were two and a half times more likely to get diabetes than women who ate plenty of roughage. Based on data from 65,000 women participating in the long-running Nurses' Health Study at Harvard University, this was the first large-scale study to uncover a dietary link to diabetes.

Roughage lowers the need for insulin by slowing the absorption of carbohydrates, and preventing surges in blood sugar, scientists explain, while a sugary low-fiber diet is likely to induce a chronic demand for insulin. Over time, the pancreas can't make as much insulin as people with this poor diet require. The resulting condition, known as insulin resistance, is the most common cause of Type 2 diabetes. "It appears that adult-onset diabetes is largely preventable," says JoAnn Manson, M.D., an endocrinologist at Brigham and Women's Hospital in Boston. "In our studies we've found that 80 percent of adult-onset diabetes is linked to excess body weight. This is one case where heredity is not destiny."

Another study unveiled at one of the American Diabetes Association's annual conferences supports Manson's statement. An active lifestyle and healthy meals can greatly lower genetic susceptibility to diabetes, according to researchers at the National Institute of Diabetes and Digestive and Kidney Diseases. They discovered that the prevalence of diabetes among Mexican Pima Indians, who do heavy labor and eat a traditional diet of low-fat unprocessed foods like beans and handmade corn tortillas, was almost one-sixth of the rate of Arizona Pima Indians, who tend to be sedentary and favor high-calorie high-fat Western convenience foods such as hot dogs. The Arizona Pimas have the highest rate of diabetes in the world. Fifty percent of tribe members between the ages of 30 and 64 have Type 2 diabetes.

"Our results show that having a genetic predisposition to the disease doesn't mean that you'll develop Type 2 diabetes," says Leslie Schultz, a nutritional biochemist with the University of Wisconsin in Milwaukee who worked on the study. "If you can control your lifestyle, you can control, to a large extent, whether or not you develop the disease."

Since Manson's study, other scientists have done further research on the theory that fiber-rich foods may help prevent Type 2 diabetes. A study published in the May 10, 2000 issue of the New England Journal of Medicine reported that people with diabetes who eat more high-fiber grains, vegetables, and fruit can better their blood sugar and possibly avoid the need for additional diabetes medicine.

During the study, 13 patients with Type 2 diabetes spent six weeks eating the amount of fiber recommended by the American Diabetes Association - 24 grams a day. They then upped their intake of fiber to 50 grams for the next six weeks. (Among the foods added to their diets were papaya, oranges, grapefruit, sweet potatoes, raisins, granola, oat bran, and oatmeal; unlike subjects in similar studies, they didn't take any fiber supplements.) Not only did the patients see striking improvement in their blood sugar levels, they found their cholesterol levels improved as well.

Endorsing the study's findings was the Joslin Diabetes Center, a leading diabetes research institution. Joslin officials cautioned, however, that diabetics should add fiber to their diets gradually (about 3-5 grams a day) to prevent bloating. They also advised drinking at least 8 cups of liquid (besides those containing caffeine or alcohol) to ward off constipation.

And several studies have bolstered the theory that getting exercise may fend off diabetes in those at risk. The New England Journal of Medicine, for example, published a study by researchers at Yale University School of Medicine showing that after six weeks of moderate exercise, ten adult children of diabetics -- all sedentary but not overweight and all suffering from insulin resistance -- significantly improved their sensitivity to insulin.

Letitia Thomas knows well the value of regular workouts and smart food choices in high-risk people like herself. Thomas, a study coordinator at Johns Hopkins University in Baltimore, is an African American and mother of two boys; her brother, mother, and maternal grandmother all have diabetes. Thomas herself had gestational diabetes during her two pregnancies, and most of her life she has struggled in vain to lose weight. "I [thought] I couldn't escape the disease," she says. "And I was afraid."

But rather than resigning herself to failing health, Thomas decided two years ago to do something about the risk factors she could control. At that time she hit the scales at 234 pounds. she sized up her diet - heavy on fatty foods such as fried chicken and hamburgers - and her exercise routine - nonexistent - and set about changing her ways. Walking, aerobics, and working out on a treadmill are now part of her daily schedule. And she prepares low-fat meals, mostly salads, what her husband used to teasingly call "rabbit food." To date she dropped 47 pounds; she aims to shed another 30.

Thomas's husband recently learned he has diabetes, strengthening his wife's resolve to stop the disheartening cycle. She knows that to stand a decent chance of averting the disease, she'll need to stick with her new habits for a lifetime. But she's willing to try - and not just for her own sake. "I don't want to push this on my kids," she says. "Three generations is enough."

-- Sarah Henry is an award-winning health writer specializing in parenting and social issues. She was a staff writer for the Center for Investigative Reporting for more than a decade, and has also reported on health issues for Hippocrates, Time Inc. Health, the Washington Post, the Los Angeles Times Magazine, and for television programs such as "60 Minutes" and PBS's "Health Quarterly."

Further Resources

American Diabetes Association

800/342-2382

http://www.diabetes.org Joslin Diabetes Center

617/732-2400

http://www.joslin.org The Unofficial Guide to Living with Diabetes, Maria Thomas, Loren Green, M.D. Macmillan Publishers

References

First published January 22, 2001
Last updated May 10, 2004
Copyright © 2001 Consumer Health Interactive

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