New Studies Point to Natural Resistant Starch’s Health Benefits

19/10/07 Speaking at the recent “The New Fiber Story: Natural Resistant Starch” Conference in Philadelphia, top experts from around the world outlined how increased consumption of natural resistant starch, a type of dietary fiber comfortably fermented in the large intestine, could positively affect weight, glycemic management and digestive health. The fermentation of natural resistant starch, commonly consumed in foods such as beans, bananas and cold potatoes as well as in a growing number of commercial products, is believed responsible for many of the digestive and metabolic health benefits.

At the conference, organized by Oldways and Hi-maize-brand resistant starch, Dr. David Topping, a senior scientist, CSIRO National Research Flagships, Australia, explained that conditions such as constipation, colorectal cancer, diabetes, and inflammatory bowel disease are emerging as serious issues in developing countries as their levels of prosperity rise, as well as in affluent westernized countries.

“The key to lowering the risk of these diseases is fiber,” Dr. Topping said. “It is no secret that we need much more fiber in our diet but it is the type of fiber that can make real improvements in our health.”

Foods high in resistant starch (RS) are attracting the attention of leading researchers and health professionals, according to Dr. Topping, who explained the key to these benefits is the way resistant starch is digested. While most starches are digested in the small intestine and absorbed as sugar, resistant starch gets its name because it resists digestion until it reaches the large intestine. There, through fermentation, it takes on many of the roles of other undigested carbohydrates long recognized as dietary fiber – while providing some unique additional benefits.

Research indicates increased resistant starch consumption positively affects fat burning, glycemic management and intestinal health. Dr. Janine Higgins, Assistant Professor, Center for Human Nutrition, University of Colorado at Denver and Health Sciences Center, reviewed research showing how resistant starch lowers the post-prandial glucose and insulin impact of foods, improves insulin sensitivity and may increase satiety – all important factors in reducing weight gain and risk for diabetes. She presented research indicating that consuming resistant starch makes the body prioritize fat metabolism over carbohydrate metabolism. This “fat burning” effect of resistant starch could result in lower body fat in humans, which has been seen in animal studies, if consumed over the long-run. Dr. Higgins also shared new research demonstrating that resistant starch prevented weight re-gain after weight loss almost as much as exercise in animals.

Dr. Michael Keenan, Associate Professor, Division of Human Nutrition and Food, Louisiana State University AgCenter, demonstrated how natural RS is fermented by the bacteria in the large intestine where they produce short-chain fatty acids. Dr. Keenan's research shows that these fatty acids turn on the production of two gut hormones, Peptide YY ("PYY") and Glucagon-like peptide-1 ("GLP-1") that play an important role in signaling our bodies to start or stop eating. Surprisingly, cellulose, another dietary fiber that provides bulking but is not fermented, did not have the same effect. According to Dr. Keenan, gastric bypass surgery also results in increased levels of these two hormones. Dr. Keenan shared new research demonstrating that high levels of dietary fat interfere with the fermentation of natural RS and prevents the increase in GLP-1 and PYY that is seen with low and moderate fat diets. This indicates that the fermentation process may be even more important than caloric intake.

Dr. Topping also explained how dietary consumption of resistant starch may reduce the risk of colorectal cancer and other colonic diseases. African Americans have high rates of large bowel disease, but native populations, such as in South Africa, that consume traditional diets high in unrefined grains have very low rates of these diseases. It had been believed that the traditional diets were high in fiber, but they are actually not – they are high in resistant starch. The fermentation of this naturally occurring resistant starch may be responsible for the reduced rate of disease.

Author and diabetes expert Hope Warshaw stressed the importance of setting “doable goals” for consumers when it comes to resistant starch consumption and reinforced that small behaviour changes lead to big impacts on health. Ms. Warshaw and organizations such as Oldways are calling for Americans to start by simply doubling their resistant starch intake.

Americans consume just less than 5 grams of resistant starch daily, on average, while scientists suggest 15-20 grams or more may be optimum for health. In countries where rice and pasta are diet staples, resistant starch intake is more than double our national average, and in China it is almost 3 times greater.

“Consumers can double their current resistant starch intake easily by enjoying beans or bananas, or cold potatoes, rice and pasta which all contain naturally-occurring resistant starch,” said K. Dun Gifford, president, Oldways. “You can also find foods on the supermarket shelf containing a natural form of resistant starch from corn called Hi-maize. These are small steps you can take to improve your overall health.”