The presence of a specific gut bacteria coupled with a high-fat diet may promote weight gain. Michael Blaut, PhD, head of the German Institute of Human Nutrition’s Department of Gastrointestinal Microbiology, and colleagues investigated the role of the human gut bacterium Clostridium ramosum in 3 groups of mice. The first group harbored a simplified human intestinal microbiota (bacteria) of 8 bacterial species including Clostridium ramosum; the second harbored simplified human intestinal microbiota except for Clostridium ramosum, and the third harbored Clostridium ramosum only. Mice were fed either a high-fat diet or low-fat diet for 4-weeks. Results showed that mice harboring Clostridium ramosum gained weight when fed a high-fat diet. Conversely, mice that did not have Clostridium ramosum were less obese even when fed a high-fat diet. All groups of mice fed a low-fat diet stayed lean, indicating that the obesity effect of Clostridium ramosum only occurs in conjunction with a high-fat diet. Results also showed that mice that harboured Clostridium ramosum also had higher gene expression of glucose transporter 2 (Glut2), a protein that enables absorption of glucose and fructose, and fat transport proteins including fatty acid translocase (Cd36). “Our results indicate that Clostridium ramosum improves nutrient uptake in the small intestine and thereby promotes obesity,” Blaut concluded.
Woting A, Pfeiffer N, Loh G, Klaus S, Blaut M. Clostridium ramosum Promotes High-Fat Diet-Induced Obesity in Gnotobiotic Mouse Models. mBio. 2014;5:e01530-14.