Credit: Jennie Vallis/Macmillan Publishers Limited

New research shows that the beneficial effects of exercise on bone are correlated with changes in the composition of the gut microbiota.

“We know that exercise is good for bone and also the gut,” explains lead author Laura McCabe (Michigan State University, USA). “So, we were interested in understanding how exercise influences the effects of a high-fat diet on bone and to see if there were links to microbiota composition.” The researchers fed male C57BL/6 mice a low-fat diet (10% of calories from fat) or a high-fat diet (60% of calories from fat) and kept them under sedentary or voluntary exercise conditions for 14 weeks.

A high-fat diet has previously been reported to result in reduced trabecular bone volume in the tibia and vertebrae and increased marrow adiposity. McCabe and her colleagues replicated this finding in male mice, but also confirmed that these effects were ameliorated by exercise. The investigators also found that exercise prevented the adverse effects of a high-fat diet on the gut microbiota, resulting in a healthy gut microbiota composition.

exercise prevented the adverse effects of a high-fat diet on the gut microbiota

Interestingly, the exercise-induced changes in the gut microbiota correlated with changes in bone health parameters. “Pearson’s correlation analyses suggest several bacterial family members present in exercised mice correlate with the positive changes to bone,” adds McCabe. Microbiome analyses showed that exercise reduced the Firmicutes to Bacteroidetes ratio; furthermore, this ratio was negatively correlated with bone volume. While McCabe and co-workers recognize that further work is needed, they suggest that the changes exercise induced in the gut microbiota could be a novel mechanism via which exercise prevents the negative effects of a high-fat diet on bone.

The researchers are now working on identifying the mechanisms underlying the associations between exercise-induced changes in the gut microbiota and bone health. “We want to know how the microbiota communicate with bone and how we can manipulate the microbiota to prevent bone loss, perhaps by reproducing the microbiota associated with exercise,” concludes McCabe.