June 14, 2010 -- Replacing white rice in your diet with brown rice may reduce the risk of developing type 2 diabetes, according to a new study.
The finding is important because the consumption of white rice in the United States has increased dramatically in the past few decades, and about 18 million Americans have type 2 diabetes.
Researchers at the Harvard School of Public Health say eating two or more servings of brown rice weekly seems to be associated with a lower risk of developing type 2 diabetes. On the other hand, they report, eating five or more servings of white rice per week is associated with an increased risk.
Qi Sun, MD, now an instructor of medicine at Brigham and Women’s Hospital in Boston, and colleagues at Harvard estimate that replacing 50 grams daily of white rice (uncooked, equivalent to a one-third serving) with the same amount of brown rice would lower the risk of type 2 diabetes by 16%.
Replacing the same amount of white rice with other whole grains, such as barley and wheat, is associated with a 36% reduced risk.
The study is published in the online journal Archives of Internal Medicine.
The researchers say the study is the first to specifically examine white rice vs. brown rice in relation to development of type2 diabetes among Americans.
“Rice consumption in the U.S. has dramatically increased in recent decades,” Sun says in a news release. “We believe replacing white rice and other refined grains with whole grains, including brown rice, would lower the risk of type 2 diabetes.”
White rice is created by removing the bran and germ portions of brown rice. The authors say that more than 70% of rice eaten in the U.S. is white.
Brown Rice Reduces Diabetes Risk
The scientists examined rice consumption and diabetes risk in 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 analyzed responses to questionnaires completed every four years about diet, lifestyle, and health conditions.
After adjusting for age and other lifestyle and dietary risk factors, people who consumed five or more servings of white rice per week had a 17% increased risk of diabetes, compared to people who ate 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 of brown rice per month.
White rice has a higher glycemic index than brown rice, the researchers say. That index is a measure of how fast a particular food raises blood glucose levels, compared with the same amount of glucose.
“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,” the authors write. “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.”
They recommend replacing white rice and other refined grains with brown rice to try to prevent type 2 diabetes.
Brown rice, the researchers say, often does not generate as fast an increase in blood sugar levels after a meal.
Whole Grains Recommended
The study also reports that:
- The biggest eaters of white rice were less likely to have European ancestry or to smoke, and more likely to have a family history of diabetes.
- Eating brown rice was not associated with ethnicity, but with a more health-conscious diet and lifestyle.
- Brown rice consumption was low in the study population.
The U.S. government’s release of the current Dietary Guidelines for Americans identifies grains, including rice, as one of the primary sources of carbohydrates and recommends that at least half of grain servings come from whole grains.
“From a public health point of view, whole grains, rather than refined carbohydrates such as white rice, should be recommended as the primary source of carbohydrates” for people in the United States, Frank Hu, MD, PhD, of Harvard, says in a news release.
Samantha Heller, MS, RD, former head of the New York University Langone Medical Center’s Outpatient Cardiac Rehabilitation and Prevention Program and a spokeswoman for Diabetes Restaurant Month, an educational program sponsored by Merck, says in a news release that refined grains “can wreak havoc with blood sugar levels and energy” and increase the risk not only for type 2 diabetes but for obesity, cardiovascular diseases, and other health problems.