Taking nutritional supplements is a intentional choice that may have impact on my microbial communities. Supplements such as dietary fiber, may promote the growth of probiotics in our gut.
The choice of food we eat can have non-intentional impact on our microbial communities. More consumption of meat may inhibit the development of probiotics, as we need more time to digest meat and meat may go bad in our intestinal tract. While if we consume more vegetables, the dietary fiber contained may help the colonization of probiotics as dietary fiber is the food of them.