About two years ago a Harvard University study that found that people who ate five servings of white rice per week had a 20 percent increased risk of diabetes compared to those who ate less than one serving per month. Eating two or more servings of brown rice per week decreased the risk of diabetes by 11 percent (Arch Int Medicine, 170: 961, 2010). Brown rice contains the outer bran and germ portions of the rice grain, which slows its digestion in the gut. Manufacturing white rice removes these portions, leaving only the starchy interior.
A 16-week study from the Chinese Academy of Sciences found opposite results. Researchers compared the effects of consuming white rice or brown rice (ad libitum; they could eat as much as they wanted) on diabetes risk factors in people with type 2 diabetes. They found no differences between groups in body mass index, waist circumference, blood pressure or measures of blood sugar metabolism. They concluded that consuming brown rice had no effect on metabolic risk factors of diabetes.
Differences between the Harvard and Chinese studies could be due to genetic variations in the metabolic response to diet, cultural differences between test subjects or differences in research design. (Journal of Nutrition, 141: 1686-1690)