Background: There is a major controversy centered on the poor oral bioavailability yet high bio-efficacy of curcumin, one of the most studied bioactive dietary compounds. To address this controversy, this study elucidates the metabolic fate of curcumin in the gastrointestinal tract and its role in the anti-colitis effect of curcumin.

Method: As a part of daily diet, curcumin was administered to CD-1 mice that were treated either with or without dextran sulfate sodium (DSS) in the drinking water. Curcumin and its metabolites were determined by liquid chromatography/mass spectrometry (LC/MS) in the tissues and digesta of the mouse stomach and small intestine. The fecal bacteria from healthy mice, colitic mice, and healthy human subjects were used to determine their roles in the metabolism of curcumin. The fecal abundance of curcumin and its metabolites was determined by LC/MS in human subjects consuming curcumin supplements.

Results: Contrary to the current understanding, orally administered curcumin was well absorbed in the small intestine. It underwent dynamic biotransformation along the mouse gastrointestinal tract where intestinal mucosa and gut microbiota worked together to produce largely varied amounts of metabolites. Dietary curcumin was metabolized and excreted differently in the colon of the colitic mice compared to the healthy mice due to the difference in gut microbiota composition. Gut microbiota was responsible for the reduction, oxidation, and deconjugation of curcumin and its metabolites in the mouse colon. Characteristics of fecal metabolite profile of curcumin in the human volunteers supported the notion that curcumin followed a similar metabolic fate in humans as in mice, with a larger inter-individual variation in metabolite abundance in humans than in mice, presumably due to variation in the host enzymes and gut microbiota.

Conclusion: This work elucidates a new gut microbiota-driven mechanism by which orally administered curcumin exerts anti-inflammatory actions in the colon.

Zhengze Li

Reaserch assistant, University of Massachusetts Amherst

Appearances