The gut microbiota play important roles in lipid metabolism and absorption. However, the contribution of the small bowel microbiota of mammals to these diet-microbe interactions remains unclear. We determine that germ-free (GF) mice are resistant to diet-induced obesity and malabsorb fat with specifically impaired lipid digestion and absorption within the small intestine. Small bowel microbes are essential for host adaptation to dietary lipid changes by regulating gut epithelial processes involved in their digestion and absorption. In addition, GF mice conventionalized with high-fat diet-induced jejunal microbiota exhibit increased lipid absorption even when fed a low-fat diet. Conditioned media from specific bacterial strains directly upregulate lipid absorption genes in murine proximal small intestinal epithelial organoids. These findings indicate that proximal gut microbiota play key roles in host adaptability to dietary lipid variations through mechanisms involving both the digestive and absorptive phases and that these functions may contribute to conditions of over- and undernutrition. Martinez-Guryn et al. demonstrate that small intestinal microbiota are critical transducers of dietary signals that allow the host to adapt to variations in lipid digestion and absorption. High-fat diet-induced jejunal microbiota directly promote mucosal lipid absorption and are potentially a factor contributing to conditions of over- and undernutrition.
Martinez-Guryn, K., Hubert, N., Frazier, K., Urlass, S., Musch, M. W., Ojeda, P., … Chang, E. B. (2018). Small Intestine Microbiota Regulate Host Digestive and Absorptive Adaptive Responses to Dietary Lipids. Cell Host and Microbe, 23(4), 458-469.e5. https://doi.org/10.1016/j.chom.2018.03.011