Journal Article

Developing a model for estimating the activity of colonic microbes after intestinal surgeries

Davis, Taylor L., Rittmann, Bruce E., DiBaise, John K., Corbin, Karen, Krajmalnik-Brown, Rosa, Carnero, Elvis A., Smith, Steven R., Marcus, Andrew

2021

Overview

The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection. We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps. First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon's microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection. For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy. The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon's microorganisms.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Absorption / Biology and Life Sciences / Biotechnology / Carbohydrates / Colon / Ecology and Environmental Sciences / Energy / Energy intake / Energy recovery / Energy value / Fatty acids / Food / Food energy value / Gastrointestinal system / Gastrointestinal tract / Health aspects / Intestinal bypass / Intestine / Large intestine / Least squares method / Mathematical models / Medicine and Health Sciences / Metabolism / Microbiota (Symbiotic organisms) / Microorganisms / Nutrients / Nutrition research / Ostomy / Physical Sciences / Physiological aspects / Physiology / Proteins / Regression analysis / Small intestine