Most starches are digested and absorbed into the body through the small intestine, but some resist digestion and pass through to the large intestine where they act like dietary fibre and improve digestive health. This type of starch is called resistant starch.
And tapping into opportunities gleaned from the growing trend for health and wellness foods, resistant starches fit squarely into the low-glycaemic food trends, as well as health product positions such as prebiotic fibre benefits and a healthy digestive system.
The growing popularity of the Glycaemic Index diet (GI), a regime that ranks foods based on their effect on blood glucose levels, is encouraging food makers to launch new food brands onto the shelves that incorporate low-GI ingredients in their recipes.
Much of the popularity is linked to the phenomenon that high blood sugar is known to be the defining feature of diabetes.
The majority of new low-GI food products are designed to help prevent the onset of type 2 diabetes. This condition has surged in recent years with the increase in obesity and now affects an estimated 19 million people in the 25 members states of the European Union (over 4 per cent of the population).
For their small study researchers at Oxford University studied the impact of resistant starch on insulin sensitivity and tissue metabolism in ten participants.
Over four weeks, study volunteers were given 30 g resistant starch/d, compared with a placebo, and assessed the results by using arteriovenous difference methods.
"Insulin sensitivity was higher after resistant starch supplementation than after placebo treatment," report the scientists in the September 2005 issue of the American Journal of Clinical Nutrition
Forearm muscle glucose clearance during the meal tolerance test was also higher after resistant starch supplementation, despite lower insulin concentrations, they add.
Although the researchers suggest that dietary supplementation with resistant starch has the potential to improve insulin sensitivity, they warn that further studies in insulin-resistant persons are needed.
Cashing in on the mounting popularity of resistant starches, earlier this month ICI-owned National Starch applied for EU approval of a resistant starch as a novel food ingredient.
Although phosphated di-starch phosphate, a modified resistant starch made from high amylose maize starch, is currently used as food additive (E1413) in the EU, the firm is pushing to market it as a novel food ingredient low moisture food products, including biscuits, pasta and bread.