March 18, 2012
Switching From White Rice To Brown Rice Dramatically Improves Blood Sugar
Fitness and nutrition experts have been touting it for years. There is a distinct advantage of eating brown rice over white. White rice is also joining the growing list of refined carbohydrates with links to a significantly increased risk of type 2 diabetes if eaten regularly.
Researchers from the Harvard School of Public Health (HSPH) have found that eating five or more servings of white rice per week was associated with an increased risk of type 2 diabetes. In contrast, eating two or more servings of brown rice per week was associated with a lower risk of the disease.
The researchers estimated that replacing 50 grams of white rice (just one third of a typical daily serving) with the same amount of brown rice would lower risk of type 2 diabetes by 16%. The same replacement with other whole grains, such as whole wheat and barley, was associated with a 36% reduced risk.
Their study seeks to determine whether this risk is dependent on the amount of rice consumed and if the association is stronger for the Asian population, who tend to eat more white rice than the Western world.
The authors analysed the results of four studies: two in Asian countries (China and Japan) and two in Western countries (USA and Australia). All participants were diabetes free at study baseline.
White rice is the predominant type of rice eaten worldwide and has high GI values. High GI diets are associated with an increased risk of developing type 2 diabetes. The average amount of rice eaten varies widely between Western and Asian countries, with the Chinese population eating an average of four portions a day while those in the Western world eat less than five portions a week.
The researchers, led by Sun, and senior author Frank Hu, professor of nutrition and epidemiology at HSPH, examined white and brown rice consumption in relation to type 2 diabetes risk in 157,463 women and 39,765 men participating in the Brigham and Women's Hospital-based Nurses' Health Study I and II and the Health Professionals Follow-up Study. The researchers analyzed responses to questionnaires about diet, lifestyle, and health conditions which participants completed every four years. They documented 5,500 cases of type 2 diabetes during 22 years of follow-up in NHS 1 participants, 2,359 cases over 14 years in NHS II participants, and 2,648 cases over 20 years in HPFS participants.
Sun and his colleagues found that the biggest consumers 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. In the analysis, researchers adjusted for a variety of factors that could influence the results, including age, body mass index, smoking status, alcohol intake, family history of diabetes, and other dietary habits, and found that the trend of increased risk associated with high white rice consumption remained. Because ethnicity was associated with both white rice consumption and diabetes risk, the researchers conducted a secondary analysis of white participants only and found similar results.
White rice has a lower content of nutrients than brown rice including fibre, magnesium and vitamins, some of which are associated with a lower risk of type 2 diabetes. The authors report, therefore, that a high consumption of white rice may lead to increased risk because of the low intake of these nutrients.
Nutritional Comparison of Brown Rice vs. White Rice
Source: USDA Nutrient Data Laboratory
Although rice currently makes up a small portion of most U.S. diets (generally less than two percent of total daily energy intake), in other parts of the world, such as Japan, rice can be responsible for nearly 30 percent of daily average energy intake, Sun and his colleagues noted. Nevertheless, the researchers concluded in their paper, "From a public health point of view, replacing refined grains such as white rice by whole grains, including brown rice, should be recommended" to help prevent type 2 diabetes.
Natasha Longo has a master's degree in nutrition and is a certified fitness and nutritional counselor. She has consulted on public health policy and procurement in Canada, Australia, Spain, Ireland, England and Germany.