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RECIPROCAL INTERACTIONS BETWEEN RED RASPBERRY POLYPHENOLS AND GUT MICROBIOME COMPOSITION AND METABOLIC HEALTH
Title
RECIPROCAL INTERACTIONS BETWEEN RED RASPBERRY POLYPHENOLS AND GUT MICROBIOME COMPOSITION AND METABOLIC HEALTH
Creator
Zhang, Xuhuiqun
Date
2020
Description
Red raspberries (RRB) and fructo-oligosaccharides (FOS) have been associated with reduced risk of developing cardio-metabolic diseases. RRB...
Show moreRed raspberries (RRB) and fructo-oligosaccharides (FOS) have been associated with reduced risk of developing cardio-metabolic diseases. RRB are uniquely high in anthocyanin- and ellagitannin- type (poly)phenols, however, these (poly)phenols have low bioavailability. Gut microbiota can improve (poly)phenol bioavailability through fermentation processes generating absorbable metabolites and altering gut microbiota structure. However, clinical evidence on the effects of RRB intake on the gut microbiome, (poly)phenolic metabolites and metabolic health is lacking. Further, fermentable carbohydrates (FOS) that selectively stimulate gut microbiota growth may enhance metabolite generation. Therefore, the aim of this research is to investigate the interactions between the gut microbiome and RRB, and explore added effects of FOS as a possible nutritional strategy for improving metabolic health of at risk individuals with prediabetes and insulin resistance (PreDM-IR). Through a series of investigations drawn from a randomized clinical trial (RCT), the following hypotheses were tested: 1) Individuals with PreDM-IR will have a distinctive gut microbiome, and lower capacity to metabolize (poly)phenols compared to healthy individuals; 2) RRB intake for 4-week will increase microbial-derived (poly)phenolic metabolites and adding FOS will augment the effect; 3) RRB intake will improve metabolic risk factors in PreDM-IR and adding FOS will augment the RRB effect; 4) RRB and RRB+FOS supplementations will alter the structure of the gut microbiome explaining variances observed in metabolites and metabolic outcomes. In this single-blinded, crossover RCT, adults with PreDM-IR (n=26) and a healthy group (n=10) consumed 1 cup RRB (fresh weight equivalence) per day or RRB with 8g FOS per day for 4 weeks in random order separated by 4-week washout. Metabolic risk factors, (poly)phenolic metabolites and metagenomic profile were assessed before and after supplementation. Baseline characterization before supplementation revealed distinctive metabolites and metagenomics profiles related to metabolic status. After 4-week RRB, microbial (poly)phenolic metabolites, metabolic health indices and gut microbiome structure beneficially shifted in PreDM-IR group. Adding FOS increased specific microbial species and phenolic metabolites that correlated with β-cell function in PreDM-IR. Overall, nutritional strategies incorporating RRB and FOS may improve metabolic health of individuals with PreDM-IR through modulating gut microbiome composition and the capacity to metabolize RRB (poly)phenols.
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