Starch is a type of complex carbohydrate produced by most green plants as an energy store. It is the most common carbohydrate in human diets and is contained in numerous staple foods such as potatoes, wheat, corn, and rice. Carbohydrates, such as starches, provide the majority of fuel for your body, so it makes up a significant part of your caloric intake. Sometimes, not all of the starch we consume gets digested, a small part of it passes through the digestive tract unchanged. This type of starch is called resistant starch, which functions kind of like soluble fiber.
Many studies in humans have shown that resistant starch can have powerful health benefits. This includes improved insulin sensitivity, lower blood sugar levels, reduced appetite and various benefits for digestion.(1) Unlike most starches, resistant starch does not release glucose within the small intestine. Rather, it reaches the large intestine where it is consumed or fermented by colonic bacteria turning it into short-chain fatty acids (SCFAs).(2)
Fibers that are fermented by colonic bacteria are known as prebiotics, although not all fibers act as prebiotics.(3) Acetate, propionate and butyrate are SCFAs derived from fermentable fiber, and are produced in a ratio of approximately 60:20:20—this ratio can be modified by changing the diet.(4,5,6) For example, adding more resistant starch can increase the proportion of butyrate.(7)
Although a primary role of SCFAs, and butyrate, in particular, is to help nourish the cells that line the colon, emerging research suggests involvement in numerous biochemical signaling processes throughout the body.(6,8) For example, SCFAs have shown immune-modulating, anti-inflammatory and anti-proliferative properties that affect different aspects of gastrointestinal health, glucose homeostasis and energy balance.(8) It is clear that SCFAs play an important role in many physiological processes and may be important markers for many different diseases and conditions.(5,8) However, since many of these findings are based on animal studies, their application to human health is unknown.(9)
You can increase your resistant starch intake by adding foods from this list to your diet, or supplementing with raw potato starch which contains about 8 grams of resistant starch per tablespoon and almost no usable carbohydrate – a great option for people on a low carb diet.
References:
- A. P. Nugent. Health properties of resistant starch. Nutrition Bulletin. 30(1), 27-54.
- Sharma, Alka; Yadav, Baljeet Singh; Ritika (2008). “Resistant Starch: Physiological Roles and Food Applications”. Food Reviews International. 24 (2): 193–234.
- Slavin J et al. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013 Apr 22;5(4):1417-35.
- Clarke G et al. Minireview: Gut microbiota: the neglected endocrine organ. Mol Endocrinol. 2014 Aug;28(8):1221-38.
- den Besten G et al. The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism. J Lipid Res. 2013 Sep;54(9):2325-40.
- Wong J et al. Colonic health: fermentation and short-chain fatty acids. J Clin Gastroenterol. 2006 Mar;40(3):235-43.
- Sajilata M et al. Resistant starch—a review. Compr Rev Food Sci Food Saf. 2006 Jan;5:1-17.
- Koh A et al. From dietary fiber to host physiology: short-chain fatty acids as key bacterial metabolites. Cell. 2016 Jun 2;165(6):1332-1345.
- Byrne C et al. The role of short-chain fatty acids in appetite regulation and energy homeostasis. Int J Obes (Lond). 2015 Sep;39(9):1331-8.
