The inter-individual variability of blueberry anthocyanin metabolism and its impact on cardiovascular risk factors

Haag, Laura (2021) The inter-individual variability of blueberry anthocyanin metabolism and its impact on cardiovascular risk factors. Doctoral thesis, University of East Anglia.

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Anthocyanins, a subclass of flavonoids, are plant metabolites found in commonly consumed red-, blue-, and purple-coloured fruits and vegetables. In population-based studies, habitual anthocyanin intakes have been associated with reduced risk for cardiovascular diseases. However, there is contradictory evidence gained from randomised controlled trials as wide inter-individual variability in response to anthocyanin intake has been repeatedly observed. A contributing factor is likely to be variability in absorption and metabolisation of anthocyanins, which suggests that individuals are exposed to different levels of potentially clinically bioactive compounds, and which may underpin classification of individuals as ‘responders’and ‘non-responders’. In contrast to other flavonoid subclasses (i.e. isoflavones, ellagitannins) with unique, metabotype-defining catabolites (i.e. equol and urolithins, respectively), anthocyanins are metabolised to a set of metabolites common to many flavonoids. To date, this commonality in metabolism end-products has added complexity to the identification of a specific metabotype for anthocyanins.

This research gap is addressed in this thesis by using a combination of factor analysis and univariate methods to identify a group of seven urinary metabolites proposed to describe a responder or ‘high metaboliser’ of anthocyanin intake: 4-hydroxyhippuric acid, 3-hydroxyhippuric acid, hippuric acid, syringic acid, homovanillic acid, dihydroferulic acid, and 3,5-dihydroxyphenylpropionic acid. In addition, this thesis tested the relationship between the anthocyanin ‘responder’ metabolite profile and flow-mediated dilation (FMD) and confirmed a strong association (β=0.79, p=0.02) with each doubling in excretion of the panel metabolites associated with a 0.8% increase in FMD.

The results suggest that individuals with a high metaboliser profile may experience greater vascular benefits from the consumption of anthocyanin-rich blueberries than lower metaboliser profiles. To confirm its usefulness as a screening tool, the identified metabolite panel was applied to an ongoing dietary intervention study for the prospective recruitment of individuals classified as high or low metabolisers following a single dose of blueberries.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Chris White
Date Deposited: 08 Feb 2022 09:19
Last Modified: 08 Feb 2023 01:38


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