Dietary Fiber and Exercise: Effects on Muscle Function, Cognition, and Short‐Chain Fatty Acids in Mice

Short chain fatty acids (SCFAs) contribute to immune and brain function and are produced by gut bacteria through metabolism of fermentable fiber. We examined the relationship between dietary fiber and changes in cognition, muscle function, and cecal SCFA content with or without voluntary exercise in mice. Six‐week old male C57Bl/6J mice were fed AIN‐93M diet (Ctrl) or AIN‐93M with 5% pectin (Pect) substituted for cellulose for 6 weeks and voluntarily exercised on a wheel (VWR) or remained sedentary (SED), constituting 4 groups of N=5/group (Ctrl‐Sed, Ctrl‐VWR, Pect‐Sed, Pect‐VWR). Mice underwent a battery muscle and cognitive function testing after 4 weeks of feeding, and at sacrifice, we collected cecal contents for quantitation of SCFAs. VWR did not affect body weight over the course of the intervention, while Sed mice gained 2 grams (p<0.001, time*VWR). Neither VWR or dietary fiber type affected performance on the active avoidance task or Morris Water Maze task. Interestingly, both dietary fiber and VWR decreased grip strength, although only the pectin effect remained after normalization to body weight (p=0.004). VWR unsurprisingly increased performance on the rotarod (p=0.028) and exhaustive fatigue test (p=0.012). Pectin increased cecal concentrations of SCFAs acetate (p=0.001), propionate (p=0.002), and butyrate (p=0.005). Interestingly, VWR significantly increased acetate (p=0.030), and there was a significant VWR effect (p=0.002) and VWR*fiber interaction (p=0.031) such that the pectin + VWR group had the highest concentration of cecal propionate. In conclusion, pectin and/or VWR did not affect cognitive function but increased cecal SCFAs in young mice. These results may have implications for nervous system and immune functions. Support or Funding Information Funded by the Abbott‐UIUC Center for Nutrition, Learning, and Memory