Low doses of natural Hi-maize resistant starch could improve insulin sensitivity in men at risk for prediabetes, according to a study underwritten by National Starch LLC, a business unit of Corn Products International. The American Diabetes Association defines prediabetes as a non-disease state where blood sugar (glucose) levels are higher than normal, but not yet high enough to be diagnosed as diabetes. Study leader Kevin Maki, PhD, of Biofortis-Provident Clinical Research presented results at Experimental Biology 2011 in April.

The randomized, double-blind, controlled, crossover trial consisted of three 4-week treatment periods, separated by 3-week washouts. Participants were overweight and obese men and women, 18 to 69 years of age with elevated waist circumference: a marker for insulin sensitivity. They consumed either 15 or 30 grams/day of resistant starch (measured as dietary fiber) from Hi maize resistant starch, with a control starch including no resistant starch.

Insulin sensitivity index was assessed at the end of each period using an insulin-modified intravenous glucose tolerance test (minimal model). The men experienced a statistically significant average improvement in insulin sensitivity of 56.5% and 72.7% for the low- and high-dose treatments, respectively. In contrast, the same study did not find an improvement in insulin sensitivity in overweight women. The authors suggested that responses in women might have differed, as they were less insulin-resistant at baseline and changes over the menstrual cycle may have obscured the effects.

While a positive insulin sensitivity effect has been reported in previous trials with Hi-maize resistant starch, this was the first study to examine the lower dose of 15 g/d. The study suggests that dietary consumption of modest levels of Hi-maize resistant starch on a regular basis can help individuals at risk for prediabetes maintain healthy blood sugar levels. For more information: www.resistantstarch.com