Resistant starch is resistant to digestion and absorption in the human small intestine, but it has complete or partial fermentation in the large intestine. Consumption of natural resistant starch by humans has been shown to result in decreased glycemic response in healthy individuals, decreased glycemic response in diabetics and increased insulin sensitivity in healthy individuals. Natural resistant starch helps maintain a healthy colon and digestive system by encouraging the growth of healthy bacteria in the bowel, discouraging the growth of potentially harmful bacteria and by producing short-chain fatty acids, such as butyrate. Butyrate is important for colon health because it is the primary energy source for colonic cells and has anti-inflammatory properties that are important for keeping colon cells healthy. There has been a steady increase in knowledge of the sources, uses and physiological effects of resistant starch. However, it has only been in the past decade that the use of ingredients with high-resistant starch content has occurred in foods. More information is needed to learn about the complicated physiological functions and health benefits of resistant starch. The impact of resistant starch on blood glucose response, satiety and gut microbiota composition will be discussed, as will metabolism in animal models and individual human subjects. The results to support the prevention of colon cancer by resistant starch will be examined.