Hi-Maize Resistant Starch Improves Insulin Sensitivity in Individuals with Insulin Resistance and Metabolic Syndrome

Who consumed 40 grams of dietary fiber from Hi-maize resistant starch per day increased their hepatic insulin sensitivity by 54%, their peripheral (muscle) insulin sensitivity by 24% and their glucose uptake into forearm muscle by 68%.

12/06/09 Preliminary results from a University of Surrey clinical study found that the consumption of Hi-maize? resistant starch significantly increased insulin sensitivity in individuals with insulin resistance and metabolic syndrome. Reversing this insulin resistance may reduce the risk of developing type 2 diabetes, as well as cardiovascular disease, and could help to prevent some of the 190,000 deaths (nearly 1 in 10 deaths) that occur annually in the United States due to high blood glucose levels and related conditions.

The 8-week randomized, crossover study, conducted by Dr. Denise Robertson and her colleagues at the University of Surrey in the United Kingdom and funded by Diabetes UK, showed that 10 overweight individuals with insulin resistance and metabolic syndrome who consumed 40 grams of dietary fiber from Hi-maize resistant starch per day increased their hepatic insulin sensitivity by 54%, their peripheral (muscle) insulin sensitivity by 24% and their glucose uptake into forearm muscle by 68%. They also had reduced fasting insulin levels, reduced postprandial insulin responses to a standardized meal and significantly lower levels of fasting non-esterified fatty acids (NEFAs). Insulin sensitivity was measured by the hyperinsulinemic-euglycemic insulin clamp (the gold standard for measuring insulin sensitivity), as well as indirectly via a meal tolerance test. These preliminary research results were presented at the Diabetes UK Annual Professional Conference, held March 11-13, 2009, in Glasgow, UK, and published in the March issue of Diabetic Medicine.

“These improvements are actually bigger than you get with most blood glucose-lowering drugs,” said Dr. Robertson, lecturer in Nutritional Physiology within the Postgraduate Medical School at the University of Surrey and the principal investigator of the study. “We are finding that subjects at increased risk of developing type 2 diabetes, such as those with metabolic syndrome, are more responsive to the insulin-sensitizing effects of resistant starch than people with normal blood glucose levels. The complete results of the study will be published as soon as the data from all the participants can be analyzed.”

Research published in 2003 and 2005 by Dr. Robertson and her colleagues has already demonstrated that consumption of Hi-maize resistant starch increased insulin sensitivity in people with normal blood glucose levels. The most recent 2005 study found a 33% increase in insulin sensitivity following a meal tolerance test and a 14% improvement in insulin sensitivity as measured by the euglycemic clamp in people with normal blood glucose levels. Another research team in China published a 2007 study that demonstrated that Hi-maize also increased insulin sensitivity in people with type 2 diabetes, as indirectly measured by a meal tolerance test.

Dietary interventions to control blood glucose levels are important because high blood glucose causes more deaths in the United States than high LDL cholesterol, high dietary salt, low dietary omega-3 fatty acids or high dietary trans fatty acids, according to a recent analysis focused on identifying modifiable factors responsible for premature or preventable deaths.2 The Centers for Disease Control has estimated that 57 million American adults have pre-diabetes (either impaired fasting glucose or impaired glucose tolerance, which indicates the presence of insulin resistance). These individuals have approximately five-fold the higher risk of developing type 2 diabetes and approximately twice the risk of developing cardiovascular disease than individuals without this condition.

Consumers are also very interested in foods that promote healthy blood glucose: 69% of primary grocery shoppers are extremely or very interested in buying or using foods or drinks if they can help manage blood sugar.8 In addition, 43% of primary grocery shoppers thought that “helps maintain healthy blood sugar levels” was an extremely or very important claim on food labels.