Bidirectional interactions between dietary curcumin and gut microbiota

Curcumin is a polyphenolic compound with a long history of use as an herbal remedy, dietary spice, and food-coloring agent. Despite curcumin possesses a wide range of biological and pharmacological activities, it exhibits extremely poor bioavailability, which makes its pharmacology intriguing and also hinders its clinical application. In recent years, there is ample evidence supporting the associations between the alteration of gut microbiota and many diseases. Interestingly, after oral administration, curcumin shows its preferential distribution and accumulation in the intestine. In view of the above aspects, we reviewed the updated knowledge regarding the bidirectional interactions between curcumin and gut microbiota from two perspectives: (1) gut microbiota regulation by curcumin and (2) curcumin biotransformation by digestive microbiota. Besides the study deals with 3 potential pharmacological implications: (1) identification of metabolites being more active and bioavaliable than parent curcumin; (2) assessment of contribution of gut microbiota regulation of curcumin to its pharmacological effects and (3) development of gut microbiota regulation-based disease prevention/treatment strategy for curcumin in view of its clinical safety. This review is important to deepen our understanding of the mechanisms of action of curcumin and to provide future directions about how to use this natural compound to combat human diseases.