Resistant starch: metabolic effects and potential health benefits

Although there is strong evidence that the amount and type of fat in the diet can have dramatic effects on metabolism, the case for carbohydrate subtypes influencing metabolic parameters is emerging. By definition, resistant starch (RS) is any starch that is not digested in the small intestine but passes to the large bowel. Here, RS is a good substrate for fermentation which gives rise to an increase in short-chain fatty acid production. The differing rates of absorption between RS and digestible starch are thought to denote their differential metabolic responses. RS intake is associated with several changes in metabolism which may confer some health benefits. RS intake seems to decrease postprandial glycemic and insulinemic responses, lower plasma cholesterol and triglyceride concentrations, improve whole body insulin sensitivity, increase satiety, and reduce fat storage. These properties make RS an attractive dietary target for the prevention of diseases associated with dyslipidemia and insulin resistance as well as the development of weight loss diets and dietary therapies for the treatment of Type 2 diabetes and coronary heart disease. This review analyzes the body of literature examining the metabolic effects of RS consumption and discusses possible mechanisms whereby increased short-chain fatty acid production in the bowel could account for some of these effects. The effects of RS in the large bowel per se are the topic of other reviews and are not addressed in this paper.