Substituting brown rice or another whole grain for white rice can help reduce the risk of type 2 diabetes, new research suggests.
Five or more servings of white rice a week increased the risk of type 2 diabetes by 17%, according to the study, which is published in the Archives of Internal Medicine. But replacing white rice with brown rice could reduce the risk of developing type 2 diabetes by 16%, the study found.
"This is an important message for public health. White rice is potentially harmful for the risk of type 2 diabetes," said the study's lead author, Dr Qi Sun, an instructor of medicine at Harvard Medical School and a researcher at Brigham and Women's Hospital in Boston.
"Over the last decade, rice consumption in the US has really increased a lot, but more than 70% of the rice consumed is white rice," said Sun, who added, "People should replace white rice with brown rice or whole grains."
The reason that brown rice may offer some protection, according to Sun, is that it still contains many of the nutrients and fiber that are stripped away in the production of white rice. During the refining and milling process necessary to make white rice, the rice loses a significant amount of its fiber and most of the vitamins and minerals, according to the study.
"When you have just the white rice, it's mostly protein and starch, and you're making freer carbohydrates that are easy to digest," said Dr Jacob Warman, chief of endocrinology at the Brooklyn Hospital Centre in New York City.
"With white rice, the digestive enzymes can more easily penetrate the rice grains and release the starch for digestion. After ingesting white rice, blood sugar increases more rapidly," Sun said.
How the study was done
To analyse how those differences affect the body over the long term, Sun and his colleagues culled data from three different studies involving nearly 200 000 participants. The studies (Health Professionals Follow-up Study and the Nurses' Health Study I and II) included 39 765 men and 157 463 women, and contained detailed data on dietary intake that was updated every four years over a 14- to 22-year follow-up.
After adjusting the data to control for many other factors that could contribute to type 2 diabetes - such as body mass index, family history, age and other dietary habits - the researchers found that the consumption of white rice was associated with an increased risk of developing type 2 diabetes, while regular consumption of brown rice was linked to a reduced risk.
People who ate at least five servings of white rice a week had a 17% increased risk of type 2 diabetes, while those who ate at least two servings of brown rice a week reduced their risk of type 2 diabetes by 11%.
The researchers estimate that if people replaced white rice with brown rice, the risk of type 2 diabetes would go down by 16%.
One problem Sun and his colleagues discovered while doing the study was that brown rice consumption was relatively low during the study period. It's only in recent years that brown rice is becoming more popular. So, the researchers also evaluated the effect that replacing white rice with whole grains would have and found that the risk of diabetes would be 36% lower.
"There was a very strong association between whole grains and a decreased risk of type 2 diabetes. We recommend replacing white rice with brown rice or other whole grains," said Sun.
"In general, bulking up on grains is a good idea, and this - switching to brown rice from white - is such an easy substitution to make," said Warman. - (HealthDay News, June 2010)