BEIJING, Aug. 14 (Xinhua) -- A recent study led by Chinese researchers has shown that a gluten-free diet may increase the risk of diabetes.

Researchers from the Shanghai Institutes for Biological Sciences found that the participants in the study with lowest intake of gluten, less than four grams per day, were 13 percent more likely to develop type 2 diabetes than those with highest intake, about 12 grams per day.

Gluten is the main storage protein in wheat, barley and rye. It makes bread, pizza and pasta more chewy.

About 1 percent of the world's population are gluten intolerant, having health problems with gluten-related disorders, including coeliac disease. For them, gluten-free food is an effective treatment.

In recent years, gluten-free diets have also become popular and recommended by fitness enthusiasts as they are good for weight control.

However, previous studies have shown that a high gluten intake, about 60 to 100 grams per day, has no side effect in normal people, and a daily intake of 60 to 80 grams of gluten could reduce blood fat and blood pressure.

According to Zong Geng, lead researcher on the study, gluten-free advocates may become ill, and essential nutrients found in cereal fiber and whole grains are beneficial to health.

The research, published in the international journal Diabetologia, was based on data from nearly 200,000 American people after a follow-up of 22 to 28 years, with a validated food frequency questionnaire used to estimate gluten intake every two to four years.