Resistant starch boosts crunchiness in items like the croutons in this soup, and improves al dente texture of pasta. Photo courtesy of National Starch Food Innovation.
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The protective mechanism appears to be production of short-chain fatty acids (particularly butyrate). Butyrate not only provides energy to healthy colon cells, it may halt the progression of tumor cells. Hence, resistant starch, working either alone, complemented by other fermentable fibers (so-called non-starch polysaccharides), or in conjunction with friendly colon bacteria may provide natural protection against colon cancer. The RS2 and RS3 types appear to hold much promise in this regard and are the subjects of ongoing studies.Foods with higher amounts of amylose tend to have more resistant starch, due to the slow release of glucose from the incomplete gelatinization. This may, in turn, effect a lowered insulin response. Since blood-triglyceride levels reflect carbohydrate intake, high-amylose foods potentially lower triglycerides.Replacing a portion of dietary carbohydrates in a meal with RS2 high-amylose resistant maize has been shown to increase fat oxidation and decrease fat storage independent of the immediate glucose or insulin response. Even a reduction in plasma cholesterol may be within the healthful realm of such high-amylose starches, as has suggested studies with high amylose barley.Americans are encouraged to increase their fiber intake by increasing consumption of fruits, vegetables, whole grains and legumes. The difficulty is that we've become accustomed to staple foods without much fiber, or the texture and feel that accompanies high-fiber foods. Resistant starch is one of the products being exploited by food manufacturers to bridge both worlds.For example, it's often included as a flour ingredient to reformulate breads, muffins, and other baked goods traditionally low in fiber. Steve Hamm, director of marketing, specialty ingredients, for MGP Ingredients (
www.mgpingredients.com), Atcheson, Kan., calls resistant starch "invisible fiber," since it doesn't change the taste, texture or color of processed foods."Resistant starch can help consumers fill the gap between typical and recommended fiber intake without giving up the foods they enjoy," says Rhonda Witwer, Ph.D., development manager-nutrition for National Starch Food Innovation (
www.foodinnovation.com), Bridgewater, N.J. How the body handles resistant starch is a good example of nature displaying efficiency, taking food that escaped digestion by the normal route, and using colon bacteria to extract energy or create useful and potentially protective products. There is more complexity to carbohydrates than first meets the eye (or palate). Starches whose natural properties are preserved are protective, not damaging; strengthening, not fattening. A challenge for processors will be using and marketing resistant starch products without adding to the confusion that starch - and carbohydrates in general - have experienced by the public in the past. If successful, however, the results could be positive for all involved.