A surprising way fiber contributes to your health:

One of the ways your gut microbes contribute to overall health is through byproducts created by their fermentation of specific fibers in the GI tract. These fibers, known as ‘prebiotics’, resist decomposition and absorption in the upper GI tract but are utilized by bacteria in the colon for energy. These colonic bacteria use specific enzymes to break these fibers down into short chain fatty acids (SCFA), among other products. Acetate, propionate and butyrate are the predominate SFCAs created. These fatty acids provide energy to bacteria and also appear to also benefit their human host. (that’s us!) Short chain fatty acids lower the pH of the colon, thus inhibiting the growth of pathogenic bacterial species and promoting thriving populations of bifidiobacteria and lactobacilli species, also known as ‘the good guys’ (Slavin, 2013). SCFA also appear to play a role in the association between fiber intake and reduced risk of developing gastrointestinal disorders, cancer, as well as cardiovascular disease (Wong, deSouza, Kendall, Emam & Jenkins, 2006).

Butyrate specifically is a SCFA that is connected to cancer prevention in the research. Butyrate induces glutathione S-transferases (GST), a compound which detoxify carcinogens (Sauer, Richter, & Pool-Zobel, 2007). Stein, et al. (1996) suggest that the anticancer effect of butyrate in part may be based on the induction of GST activity, which then enhances the detoxification capacity of the gut. To sum it up, your gut bacteria can make compounds which enable your body to improve it’s ability to detox!


Our beneficial gut bacteria are very fond of fibers and resistant starches. Cooled potatoes and grains, bananas, asparagus, onions, sunchokes, leeks, dandelion greens, oats, apples, cocoa powder, burdock root and garlic are rich in the types of carbohydrate and fibers that your gut bacteria thrive on. Having these foods daily, and in abundance, will help ensure that you are taking care of your gut!


Sauer, J., Richter, K.K., & Pool-Zobel, B.L. (2007). Products formed during fermentation of the prebiotic inulin with human gut flora enhance expression of biotransformation genes in human primary colon cells. British Journal of Nutrition, 97(5), 928-37.

Slavin, J. (2013). Fiber and Prebiotics: Mechanisms and Health Benefits Nutrients, 5(4), 1417–1435.

Stein, J., Schröder, O., Bonk, M., Oremek, G., Lorenz, M., & Caspary, W.F. (1996). Induction of glutathione-S-transferase-pi by short-chain fatty acids in the intestinal cell line Caco-2. European Journal of Clinical Investigation, 26(1), 84-7.

Wong, J.M., de Souza, R., Kendall, C.W., Emam, A., & Jenkins, D.J. (2006). Colonic health: fermentation and short chain fatty acids. Journal of Clinical Gastroenterology, 40(3), 235-43.

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