Meta-analysis was done on 3,52,384 people

Each serving of polished rice a day increases the risk of Type II diabetes by 11 per cent, according to a study being published today (Friday) in the British Medical Journal.

Polished rice is commonly called white rice, and one serving refers to nearly 160 grams. "Higher consumption of white rice is associated with a significantly increased risk of Type 2 diabetes, especially in Asian (China and Japan) populations," wrote the authors from the Harvard School of Public Health, Boston.

The conclusion was based on a meta-analysis of 3,52,384 people who were followed up for four to 22 years. The participants were from China, Japan, the United States and Australia.

A "positive association" between white rice intake and increased risk of diabetes was found only in the case of the two Asian countries, where rice is a staple food. "This association seems to be stronger for Asians than for Western populations," the authors said. Despite the not-so-strong association in Western countries, the researchers estimated that about 167 new cases of diabetes per 1,00,000 people would occur every year for "every additional serving of white rice a day."

White rice primarily contains starch, as the polishing removes most of the nutrients found in the bran such as insoluble fibre, magnesium, vitamins, and lignans (a group of chemical compounds acting as antioxidants). Insoluble fibre and magnesium, for instance, have been found to lower the risk of Type II diabetes.

Double harm

Unlike brown rice, polished rice has a high glycaemic index (an indicator of glucose-raising effect of a food) and is a major contributor of dietary glycaemic load. Higher dietary glycaemic load is generally associated with the increased risk of diabetes. Hence, the harmful effects of polishing are two-pronged — it removes the nutrients that would cut the risk of diabetes and at the same time pushes up the glycaemic index, thus increasing the risk of the disease.