Eating more brown rice and other whole grains instead of white rice may help reduce the risk of Type 2 diabetes, a U.S. study suggests.

White rice is produced by removing the outer layers of brown rice grains that contain insoluble fibre, vitamins and minerals.

It's thought that white rice may add to diabetes risk, because it has a higher glycemic index, meaning it causes blood-sugar levels to rise faster than brown rice does, researchers say. In Type 2 diabetes, the body does not make enough insulin or does not use the insulin properly. As a result, sugar builds up in the blood instead of being used for energy.

Dr. Qi Sun, a nutrition researcher at the Harvard School of Public Health in Boston, and his colleagues analyzed rice intake and diabetes risk in nearly 40,000 men and more than 157,000 women in three long-term studies of doctors and nurses.

Eating five servings or more of white rice per week was associated with 1.17 times higher risk of Type 2 diabetes when compared with eating the grain less than once per month, the researchers said in Tuesday's online issue of the Archives of Internal Medicine.

During the studies that lasted from 14 to 22 years, 10,507 participants, about five per cent, developed Type 2 diabetes.

Protective effect?

"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," Sun and colleagues concluded.

"These findings could have even greater implications for Asian and other populations in which rice is a staple food."

Replacing one-third of a serving of white rice daily, about 50 grams, with the same amount of brown rice was linked with a 16 per cent lower risk of getting Type 2 diabetes, the study's authors estimated.

Eating at least two servings of brown rice was associated with an 11 per cent lower risk of developing Type 2 diabetes.

But brown rice intake was also associated with "a more health-conscience lifestyle" and diet, such as being more physically active, slimmer, and less likely to smoke or having a family history of diabetes.

The study does not show that white rice contributes to diabetes, though the consistency of the protective brown rice findings in the three studies suggest it is unlikely due to chance, the study's authors said.

High-fibre foods, such as whole grain breads, some cereals, legumes and many fruits and vegetables, help to slow the rise in blood sugar after a meal, which can help with blood sugar control.

The number of people diagnosed with diabetes in Canada is also expected to nearly double between 2000 and 2010, from 1.3 million to 2.5 million, according to the Canadian Diabetes Association.

The study was funded by the U.S. National Institutes of Health. Sun is supported by a postdoctoral fellowship from Unilever Corporate Research, which owns several food brands.