A form of dietary fiber that resists degradation by gastrointestinal (GI) enzymes in the small intestine with potential chemopreventive and prebiotic activity. Upon consumption of resistant starch, the fiber is not metabolized or absorbed in the small intestine and enters the colon unaltered. Once in the colon, the starch is fermented by anaerobic colonic bacteria and produces short-chain fatty acids (SCFA), including butyrate, which has anti-inflammatory and immunoregulatory activities. In addition, butyrate appears to exert antitumor effects by inhibiting tumor cell proliferation, inducing tumor cell differentiation and promoting apoptosis in colorectal cancer cells.

Dietary starch and related high-molecular carbohydrate incapable of enzymatic hydrolysis in the SMALL INTESTINE and instead ferments in the COLON, producing SHORT-CHAIN FATTY ACIDS by-products.