Consumption of white rice appears to increase the risk of developing type 2 diabetes, whereas consumption of brown rice appears to decrease that risk.
“Replacing refined grains such as white rice by whole grains, including brown rice, should be recommended to facilitate the prevention of type 2 diabetes,” said Dr. Qi Sun of the Harvard School of Public Health, Boston, and associates.
White rice has a higher glycemic index than does brown rice, and its relationship to type 2 diabetes has been studied in several Asian countries, where it accounts for as much as 75% of the diet. This is the first prospective study to specifically assess the relationship between the disease and the intake of both white and brown rice in a Western population, where white rice accounts for 2% of the diet, Dr. Sun and his colleagues noted.
The researchers used data from three large cohort studies that documented food intake to examine this association, assessing diet and diabetes status in 39,765 men in the HPFS (Health Professionals Follow-Up Study), 69,120 women in the NHS I (Nurses' Health Study I), and 88,343 women in the NHS II.
There were 2,648 incident cases of diabetes during 20 years of follow-up in the HPFS, 5,500 cases during 22 years of follow-up in the NHS I, and 2,359 cases during 14 years of follow-up in the NHS II.
Greater consumption of white rice was linked to a higher risk of diabetes across all three studies. This link was attenuated after the data were adjusted to account for lifestyle and dietary risk factors, “but a trend of increased risk associated with high white rice intake remained,” the researchers said.
Compared with those in the lowest category of white rice intake, “participants who had at least 5 servings of white rice per week had a 17% higher risk of developing type 2 diabetes” (Arch. Intern. Med. 2010;170:961-9).
Greater consumption of brown rice was linked to a lower risk of diabetes. This link was attenuated but remained significant after the data were adjusted to account for risk factors.
“When compared with the participants who ate less than 1 serving of brown rice per month, the pooled risk reduction of type 2 diabetes was 0.89 for intake of 2 or more servings per week,” Dr. Sun and colleagues said.
The study involved working, highly educated health professionals of predominantly European ancestry. The findings may not be generalizable to other populations, they said.
Disclosures: The study was funded by the National Institutes of Health. Dr. Sun, supported by Unilever Corporate Research, reported no financial conflicts.