Physical activity, independent of diet, shifts the composition of bacteria in the intestines, spurring researchers to search for species that might provide benefits akin to working out.
Research in mice and humans is beginning to establish a link between the composition of microbes in the gut and immune responses to tumor cells, but the mechanisms are not yet clear.
The gut microbiome has been linked to depression, schizophrenia, and other neurological conditions, but it’s not yet clear whether the relationship is causal.