For most people around the world, it’s a staple food. In the U.S., rice is becoming increasingly popular as well — since the 1930s, Americans’ rice consumption has grown threefold to about 21 lbs. per person a year. So it bears asking whether rice is a healthy dietary choice.
A new study led by researchers at the Harvard School of Public Health sought to determine whether eating rice, how much and what kind — brown versus white — had any impact on people’s risk of diabetes over the long term. The study found a consistent effect: the more white rice people ate, the higher their risk of developing type 2 diabetes; the more brown rice they ate, the lower their risk.
People who ate five or more servings of white rice per week had a 17% higher risk of developing diabetes than people who ate white rice less than once a month. In contrast, people who ate brown rice two or more times a week were 11% less likely to develop diabetes than people who ate brown rice less than once a month.
The paper, published Monday in the Archives of Internal Medicine, mined data from three large, long-term trials — the Health Professionals Follow-up Study and the Nurses’ Health Study I and II — for a combined study population of 157,463 women and 39,765 men, ranging in age from 26 to 87. The participants were followed for 14 to 22 years, and asked periodically to fill out comprehensive questionnaires about their eating habits.
Perhaps not surprisingly, people who were in the highest brown-rice consumption group (twice a week or more) were also more likely to exhibit other health-conscious behaviors: they were more physically active, leaner and less likely to smoke or have a family history of diabetes; they also ate more fruits, vegetables and whole grains overall and less red meat and trans fats than people in the lowest brown-rice consumption group.
But even after controlling for these lifestyle factors — which are also known to reduce the risk of developing type 2 diabetes and other chronic diseases — the association between brown-rice consumption and low diabetes risk remained, the study found.
Brown rice has long been considered more a healthful option because the grain is left whole. During the refining process, white rice loses its bran and germ, which is where most of the fiber and nutrients in rice are contained. Brown rice, in contrast, retains its fiber, vitamins and minerals such as magnesium. In past studies, insoluble fiber intake has been associated with improved insulin sensitivity and decreased risk of diabetes, while higher magnesium intake has also been associated with a lower risk of diabetes and better blood-sugar metabolism.
Here’s a quick mealtime calculation from the study: replacing 50 grams (about 1.8 ounces, or a third of a serving) of white rice per day with an equal amount of brown rice would be associated with a 16% lower risk of developing type 2 diabetes. Even better, replacing white rice with whole grains (such as whole wheat or barley) would be associated with a 36% reduction in diabetes risk.