Rice gene holds clue to diabetes risk
[MANILA] Contrary to popular belief, a new study suggests that eating rice does not substantially raise blood sugar levels – thus increasing the risk of type 2 diabetes – although researchers warn that some varieties of rice may need to be avoided.
The study was published this month in the journal Rice by the International Rice Research Institute (IRRI) in the Philippines, and Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO).
It found that as many as three quarters of 235 rice varieties analysed had a low to medium glycaemic index (GI), and were therefore less likely to lead to diabetes.
GI measures the effect of carbohydrates on blood sugar levels. Low GI foods are more slowly absorbed, causing a gradual release of sugar in the body and a lower risk of diabetes. Doctors often advise diabetics to avoid rice, believing it is a high-GI food.
The findings could have important implications for Asia where rice is the staple food for 3.5 billion people, and diabetes is a growing public health concern, said Melissa Fitzgerald, who led the IRRI team.
"With or without diabetes, it will be difficult for them to give up rice," Fitzgerald told SciDev.Net.
The International Diabetes Federation estimates that by 2030, seven of the ten countries with the highest number of diabetics will be in Asia, straining public health budgets.
The researchers found that the so-called "waxy gene", and the related amylose content, are the key determinants of the GI of rice. Rice varieties with high amylose have lower GI.
Amylose is also the chemical component which makes rice either firm or sticky after cooking, influencing consumer preferences. The waxy or sticky rice types have the highest GI, but some sticky rice varieties have little or no amylose.
Rice varieties with a low to medium GI include Basmati, India's widely grown Swarna variety, and Doongara from Australia.
The researchers say that the findings will help rice breeders to develop lower GI rice by identifying varieties with better traits.
Tony Bird, a CSIRO Food Futures Flagship researcher said "this is good news for diabetics and people at risk of diabetes who are trying to control their condition through diet, as it means they can select the right rice to help maintain a healthy, low-GI diet."
But Claire Kerslake, a health counsellor and certified diabetes educator in Australia, warned that although it was true that some varieties of rice are lower in GI, "the GI is only part of the picture. You also need to take into account the total carbohydrate load".
She advised diabetics to limit carbohydrates such as rice “to half a cup per meal."