The process of refining brown rice into white rice strips away healthy nutrients and fiber, while raising the grains glycemic index. According to a new study, refining rice may also make it a contributor to diabetes risk.After adjusting for age and other lifestyle and dietary risk factors, Qi Sun, MD, ScD, of Harvard School of Public Health, and colleagues found that those who consumed five or more servings of white rice per week had a 17% increased risk of diabetes compared with those eating less than one serving per month. But eating two or more servings of brown rice per week was associated with an 11% reduced risk of developing type 2 diabetes compared to eating less than one serving per month.The researchers assessed rice consumption and diabetes risk among 39,765 men and 157,463 women in three large studies: the Health Professionals Follow- Up Study and the Nurses Health Study I and II. They published their findings in the Archives of Internal Medicine.Rice has been a staple food in Asian countries for centuries, Dr. Sun and colleagues noted. By the 20th century, the advance of grain-processing technology made large-scale production of refined grains possible. Through refining processes, the outer bran and germ portions of intact rice grains (i.e., brown rice) are removed to produce white rice that primarily consists of starchy endosperm. US rice consumption is lower than in Asian countries but is increasing rapidly, and more than 70% of the rice that Americans eat is white.In general, white rice has a higher glycemic index-a measure of how much a food raises blood glucose levels compared with the same amount of glucose or white bread-than brown rice. The high glycemic index of white rice consumption is likely the consequence of disrupting the physical and botanical structure of rice grains during the refining process, in which almost all the bran and some of the germ are removed, the researchers explained. The other consequence of the refining process includes loss of fiber, vitamins, magnesium and other minerals, lignans, phytoestrogens and phytic acid, many of which may be protective factors for diabetes risk.Based on the results, Dr. Sun and colleagues estimated that replacing 50 grams (1.76 ounces, equivalent to one-third of a serving) of white rice per day with the same amount of brown rice would be associated with a 16% lower risk of type 2 diabetes. Replacing white rice with whole grains as a group could be associated with a risk reduction as great as 36%.In fact, since the participants overall consumption of brown rice was relatively low, replacing white rice with whole grains of all kinds is probably the best strategy; the evidence for a benefit specific to brown rice is weaker. Consider other rice-like substitutes such as quinoa (see the June 2010 Healthletter), bulgur, wild rice (not technically rice at all, but the seed of an aquatic grass) and barley, as well as brown rice.The current Dietary Guidelines for Americans, now being updated, recommend that at least half of your carbohydrate intake come from whole grains. Dr. Sun and colleagues concluded, From a public health point of view, replacing refined grains such as white rice by whole grains, including brown rice, should be recommended to facilitate the prevention of type 2 diabetes.TO LEARN MORE: Archives of Internal Medicine, June 14, 2010; abstract at archinte.ama-assn.org/cgi/ content/short/170/11/961
