Consumption of resistant starch increases insulin sensitivity in overweight, obese men

Consumption of 15 to 30 grams per day of resistant starch improves insulin sensitivity in obese and overweight men, according to a study published in The Journal of Nutrition.

Resistant starch is a type of starch that is not digested but fermented in the large intestine.

Researchers from Provident Clinical Research and Consulting, Inc. and National Starch studied 11 men and 22 women. The participants had an average body mass index (BMI) of 30.6 and an average waist circumference of 105.3 centimeters. Their average age was 49.5 years.

In random order, all participants received 0, 15 and 30 grams per day of high-amylose maize type 2 resistant starch (HAM-RS2) for four-week periods each, with three-week intervals in between.

Researchers measured insulin sensitivity at the end of each four-week period using the insulin-modified I.V. glucose tolerance test.

In men, insulin sensitivity was higher after intake of 15 and 30 grams per day of HAM-RS2 than after the control treatment. In women, there was no difference among the treatments.

Nutraingredients.com reports that the study found that 30 grams a day of resistant starch may improve insulin sensitivity by 73 percent in men. In addition, insulin sensitivity improved by 56 percent at a lower dose of 15 grams a day.

The findings are consistent with previous studies, but researchers are not clear about why men and women responded differently in the study. Potential causes could include transit time of food through the gastrointestinal tract or different sensitivities to the fermentation products in the gut.

There are three types of starches. In addition to resistant starch, rapidly digestible starch is digested within 20 minutes, while slowly digestible starch takes 20 to 120 minutes to digest, according to nutraingredients.com.

Potatoes, pasta, rice, baked beans and lentils are some sources of resistant starch.

Some 25.8 million Americans, or 8.3 percent of the US population, live with diabetes. If current trends continue, one in ten adults globally could have diabetes by 2030, according to estimates by the International Diabetes Federation.

Sources: The Journal of Nutrition, nutraingredients.com