The Role of the Human Gut Microbiota in the Metabolism of Dietary Anthocyanins

Percival, Jasmine (2021) The Role of the Human Gut Microbiota in the Metabolism of Dietary Anthocyanins. Doctoral thesis, University of East Anglia.

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Background: Anthocyanin consumption has been linked to a variety of health benefits. However, anthocyanins have poor bioavailability, and consequently any biological effect of anthocyanin consumption is hypothesised to be attributed to their metabolites. Recently, there has been evidence for a bi-directional relationship between anthocyanins and the gut microbiota whereby
the microbiota largely determines how anthocyanins are metabolised while anthocyanins and/or their metabolites may modulate gut microbial populations. However, research in this field is in its infancy and much remains to be understood.
Objective: To investigate the human in vivo metabolism of two different types of anthocyanin, black rice and bilberry anthocyanins, and explore the role of the gut microbiota in anthocyanin metabolism.
Approaches: Apply optimised UHPLC-MS/MS methods to quantify anthocyanins and their metabolites in biological samples from a randomised placebo-controlled crossover trial, where volunteers consumed capsules of bilberry or black rice anthocyanin extract; and profile the gut microbiota of these same individuals using 16S and whole-genome shotgun metagenomics.
Results: Anthocyanins derived from bilberry and black rice extracts are extensively metabolised in vivo. Catechol and its phase 2 conjugates were reported for the first time as in vivo metabolites of black rice anthocyanins, and 5-hydroxyferulic acid was reported for the first time as a confirmed
bilberry anthocyanin metabolite. Metabolism of black rice and bilberry anthocyanins was subject to high inter-individual variation, but there was a clear relationship in the overall urinary excretion of anthocyanin metabolites for participants between treatments (R2 = 0.259 p = 0.0008).
Furthermore, the gut microbiota was associated with the production of anthocyanin metabolites including: catechol, phloroglucinol, and dihydrocaffeic acid, and the specific microbiota anthocyanins were exposed to was observed as a source of inter-individual variation in anthocyanin
Conclusion: This thesis supports the notion that anthocyanins are extensively metabolised in vivo to a diverse range of metabolites that are present at higher concentrations than the parent compound and thus are likely implicated in any biological effects of anthocyanin consumption.
Furthermore, the data presented supports that the gut microbiota has a critical role in this metabolism and is at least partly responsible for observed inter-individual variation in anthocyanin
metabolite profiles.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 29 Apr 2022 11:37
Last Modified: 29 Apr 2022 11:37


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