White rice linked to higher risk of type 2 diabetes

White rice, a staple in the Asian diet, has been blamed for raising the risk of type 2 diabetes because it elevates blood sugar levels right after meals. But the picture has not been as clear in other populations where rice isn't consumed nearly as often.

New research from Harvard pooling three large, long-running national studies shows that Americans who ate more white rice also had a moderately increased risk of diabetes, but Americans who ate brown rice had a slightly lower risk. Substituting brown rice or other whole grains for white rice could cut that risk by as much as 36 percent, the researchers conclude in an article published in today's Archives of Internal Medicine.

Dr. Qi Sun, who is now at Brigham and Women's Hospital but did the research with colleagues at the Harvard School of Public Health, analyzed records from the Health Professionals Follow-up Study and the Nurses' Health Study I and II. The data they reviewed included diet, lifestyle, and disease information dating to 1984 for more than 39,000 men and 157,000 women.

People who ate white rice five or more days a week had a 17 percent higher risk of type 2 diabetes than people who ate white rice less than once a month. Eating brown rice twice a week or more was associated with an 11 percent lower risk of diabetes compared to eating less than one serving a month.

The observational study can't show cause and effect for the relatively low risk of developing type 2 diabetes, but the researchers estimate that replacing one-third of a white rice serving per day with brown rice could lower that risk by 16 percent. Substituting other whole grains would be even more beneficial, reducing diabetes risk by 36 percent. The benefit stems from the higher nutrient content in complex-carbohydrate whole grains compared to refined grains.

Brown-rice eaters tended to have healthier habits than others in the study, weighing less and exercising more. But when those lifestyle factor were the same, brown rice still accounted for the difference in developing type 2 diabetes.

"If a person truly loves to eat rice, we recommend substituting brown rice for white rice. For other people, we recommend substituting whole grains for other refined carbohydrates, such as bread or rice," Sun said in an interview.