"Acute consumption of barley beta-glucan, but not resistant starch, in muffins was effective in reducing glucose and insulin responses in men who were mildly insulin-resistant," wrote lead author Kay Behall from the USDA ARS in Beltsville, Maryland.
Beta-glucan, a non-starch polysaccharide found in oats and barley, has been the subject of increasing attention with some reports showing the soluble fibre can decrease LDL-C levels.
The new study, published in the journal Nutrition Research, investigated the effect of barley beta-glucan and preformed resistant starch separately or together on glucose and insulin responses in 10 normal and 10 overweight men (average BMI 23.8 and 29.0 kg per sq.m, respectively; average age 41.9).
"Elevated glucose and insulin concentrations are the primary indicators for insulin resistance and type-2 diabetes," explained Behall. "Delaying the delivery of glucose through dietary means may assist in the management of insulin resistance."
The participants consumed a control diet for two days before the study (30 per cent fat, 55 per cent carbohydrate, 15 per cent protein) and then fasted for 10 hours before consuming glucose or one of nine experimental muffins containing three resistant starch levels (0.1, 6.1, or 11.6 g/tolerance) and 3 levels of beta-glucan (0.1, 3.1, or 5.8 g/tolerance).
The researchers report that one hour after consuming the high beta-glucan-containing muffins resulted in the lowest blood glucose concentrations (7.55 for the glucose group compared to 6.98 for low beta-glucan and 6.83 millimoles per litre for the high beta-glucan meal).
Similar results were observed for insulin responses (506 for the glucose group compared to 477 for low beta-glucan and 360 picomoles per litre for the high beta-glucan meal).
"Resistant starch content was less effective than beta-glucan in reducing glucose or insulin response," said the researchers.
They said that improvements in insulin sensitivity might require at least seven grams of resistant starch, or chronic consumption, which are far from the current typical intakes in the US and Europe.
"Beneficial reductions in glucose and insulin can result when sufficient soluble fibre from isolates or grain sources such as oats or barley is consumed," concluded the researchers.
"Consumption of food sources containing adequate levels of beta-glucan and RS should reduce the rise of type 2 diabetes."
An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132bn, with $92bn being direct costs from medication, according to 2002 American Diabetes Association figures.
Source: Nutrition Research Volume 26, Pages 644-650 "Barley beta-glucan reduces plasma glucose and insulin responses compared with resistant starch in men" Authors: K.M. Behall, D.J. Scholfield and J.G. Hallfrisch