Introduction: Anthocyanins (ANCs) are a major subclass of polyphenols and give the natural colour to many plant foods such as bilberries and black rice. There is considerable interest in their putative health benefits and people consuming high quantities of ANCs have lower risk of developing chronic diseases. However, studies of ANC bioavailability have shown that ANC derived phenolics are the main forms found in the circulation, while intact ANCs are very poorly bioavailable [1]. The availability of several human metabolites reported previously suggest that there are additional ANC degradation routes, presumably involving the gut microbiota [2]. Aim: this work was to investigate the role of gut microbiota on ANC metabolism and to identify microbial metabolites that may be responsible for delivering the beneficial effects to human health. Method and experimental design: An ANC extract from black rice was incubated with live-faecal as well as autoclaved-faecal inocula using a batch colon model [2] over 24 h (n=3). Control vessels was prepared by inoculating live-faecal and for matrix solution for standard curves preparation. HPLC was used to quantify the rate of loss of anthocyanins over time and UPLC-MS/MS and UPLC-TOF methods were used to identify and quantify the ANC metabolites that appeared. The study investigated the inter- and intra- individual differences (n=3 each). Faecal samples used in the colon model experiments were obtained from participants recruited onto the QIB Colon Model study. The study was approved by the Quadram Institute Bioscience (formally Institute of Food Research) Human Research Governance committee (IFR01/2015), and London – Westminster Research Ethics Committee (15/LO/2169). The informed consent of all participating subjects was obtained, and the trial is registered at http://www.clinicaltrials.gov (NCT02653001). Results and conclusion: Loss of ANCs occurred over 24h. However, the rate of loss of ANC was considerably faster in the presence of live faecal inoculum compared to autoclaved faeces. The most abundant initial ANC metabolites produced in the presence of gut microbiota were 3,4-dihydroxyphenylacetic acid, protocatechuic acid, phloroglucinaldehyde, catechol, and phloroglucinol carboxylic acid. The production of the most abundant metabolite, catechol, was completely microbiota-dependent, providing strong evidence that gut microbiota metabolism of ANCs is important in delivering the health benefits of ANC-rich foods.