I have to admit I'm not sure either. I can speculate a few things. For one, the study did not perform much gut microbiome analyses compared to other areas. They only identified a general reduction in diversity, which is too unspecific to be able to pinpoint specific interventions.

Second, it might also be due to the field of gut microbiota intervention itself, which has a reputation for being too unspecific and imprecise. The main reason is that the gut microbiota composition can vary widely between individuals, and we have no clear idea of what a healthy gut microbiota should look like.