The team recruited 101 participants, of which around half were given dietary supplements for seven weeks including both probiotics (so-called "good" bacteria) and prebiotics (nutrients known to promote the colonization of healthy bacteria in our guts). The rest received a placebo treatment. Before and after the intervention, participants gave blood and stool samples and were also subjected to an established behavioral test known as the "ultimatum game."
"Here, with a subtle dietary intervention over the course of seven weeks, we demonstrated for the first time (to the best of our knowledge) a causal effect of changing the gut microbiome on altruistic punishment behavior."
