Diet effects the composition of the microbial flora and inflammation in the gut

The effect of diet was tested on intestinal inflammation induced following challenge with dextran sodium sulfate (DSS) in mice. Three diets were used: Chow (CD, LabDiet 5001), Harlan Teklad (TD, TD96348), and purified diets (PD) made in our laboratory. There are multiple differences in the composition of the diets. The CD diet contained the greatest diversity of fiber. The TD diet had only one source of fiber (cellulose) and three sources of carbohydrate (lactose, sucrose, and starch). PD diets had less fiber than the other diets (3% instead of 5%) and two sources of carbohydrate (sucrose and dextrose). The TD fed mice were the most susceptible to DSS colitis followed by the CD fed mice and the PD fed mice were the least susceptible. We used the PD diet as the basis for further experimentation. Addition of extra fiber (5%, FPD), lactose (28% of carbohydrate, LPD) or both lactose and fiber (FLPD) to the PD diets increased the susceptibility of the mice to DSS colitis. The changes in diet and inflammation were associated with differences in the variety and amounts of bacteria present in the gastrointestinal tract. Future work will determine whether the changes in bacterial floral are as a direct or indirect result of the diet on the immune system and/or the bacteria. These results indicate that the effects of diet on the susceptibility to DSS colitis may be mediated via the modification of intestinal microbiota. Grant Funding Source : National Institute of Diabetes and Digestive and Kidney Diseases ( DK070781 ) and National Center for Complementary and Alternative Medicine and Office of Dietary Supplements ( AT005378 )