A recently published paper in Nature [1] stated that 27% of 835 non-antimicrobial drugs have a significative impact on gut microbiota. It is likely that a similar or greater proportion of botanicals have comparable effects. For instance, we know that curcumin increases the abundance of butyrateproducing bacteria and faecal butyrate level [2]. This could explain why, despite its very poor oral bioavailability, curcumin acts as an anti-inflammatory agent and why it is a promising therapeutic option for the treatment of inflammatory bowel disease. Berberine is another excellent example of a botanical which acts by modulating the microbiota. Knowledge of the mechanism by which berberine modulates the microbiota could lead to better understanding of the role of berberine in metabolic diseases.