Regulation of MetabolismThe gut microbiota obtains its nutrients from various sources such as consumed food ingredients and host-derived requirements such as epithelial cells and mucus. Microorganisms use these substrates to produce energy to modulate cellular processes, metabolism and growth. The gut includes pathways for carbohydrate, lipid, and amino acid metabolism (6). It is interesting to note that the metabolic action of the intestinal flora is both adaptive and renewable. Through the synthesis of short-chain fatty acids (SCFAs), B vitamins and vitamin K, commensal bacteria interact mutualistically with intestinal epithelial cells to promote differentiation, proliferation and absorption from the intestine . Together, this metabolic mechanism preserves valuable energy and digestible substrates for the host, while providing energy and nutrients for growth (9). SCFAs (mainly acetate, butyrate and propionate) are the end products of carbohydrate fermentation of dietary fiber and have many positive influences in combating metabolic and inflammatory disorders, e.g. obesity, diabetes and inflammatory bowel diseases. This is accomplished via activation of G protein-coupled receptors and alteration of transcription factors (17, 18). Microbial assembly of SCFAs, TMA, acetaldehyde, and inflammatory regulators controls host metabolic fitness through pathways that affect intestinal motility, immune function, and satiety ( 19 ). An example of lipid metabolic activity linking intestinal flora to dyslipidemia (excessive amounts of lipids) is the hydrolysis of bile salts, which are steroid acids made in the liver from cholesterol and secreted into the bile to accelerate the absorption of fat-soluble vitamins. with metabolism...... middle of paper ......ience, 336, 1262-1267.21. Ramakrishna, B.S. (2013). Role of the intestinal microbiota in human nutrition and metabolism. Journal of Gastroenterology and Hepatology, 28 (S4), 9-17.22. Cani, PD, Everard, A. and Duparc, T. (2013). Intestinal microbiota, enteroendocrine functions and metabolism. Current Opinion in Pharmacology, 13(6), 935-940.23. Xie, G., Zhang, S., Zheng, X., and Jia, W. (2013). Metabolomics approaches to characterize metabolic interactions between the host and its commensal microbes. Electrophoresis, 34(19), 2787-2798.24. Chassard, C. and Lacroix, C. (2013). Carbohydrates and the human intestinal microbiota. Current Opinion in Clinical Nutrition and Metabolic Care, 16(4), 453-460.25. Aziz, QQ, Doré, JJ, Emmanuel, AA et al. (2013). Gut microbiota and gastrointestinal health: current concepts and future directions. Neurogastroenterology and motility, 25(1), 4-15.