Rice Bran and Quercetin Produce a Positive Synergistic Effect on Human Gut Microbiota, Elevate the Level of Propionate, and Reduce the Population ofEnterobacteriaceaefamily when Determined using a Bioreactor Model

Abstract

Diet is one of the prominent determinants of gut microbiota composition significantly impacting human health. Recent studies with dietary supplements such as rice bran and quercetin have been shown to provide a beneficial impact on the host by positively influencing the gut microbiota. However, the specific bacterial species impacted when rice bran or quercetin is present in the diet is not well understood. Therefore, in this study, we used a minibioreactor array system as a model to determine the effect of quercetin and rice bran individually, as well as in combination, on gut microbiota without the confounding host factors. We found that rice bran exerts higher shift in gut microbiome composition when compared to quercetin. At the species level, Acidaminococcus intestini was the only significantly enriched taxa when quercetin was supplemented, while 15 species were enriched in rice bran supplementation and 13 were enriched when quercetin and rice bran were supplemented in combination. When comparing the short chain fatty acid production, quercetin supplementation significantly enriched isobutyrate production while propionate dominated the quercetin and rice bran combined group. Higher levels of propionate were highly correlated to the lower abundance of the potentially pathogenic Enterobacteriaceae family. These findings suggest that the combination of rice bran and quercetin serve to enrich beneficial bacteria and reduce potential opportunistic pathogens. However, further in vivo studies are necessary to determine the synergistic effect of rice bran and quercetin on host health and immunity.ImportanceRice bran and quercetin are dietary components that shape host health by interacting with the gut microbiome. Both these substrates have been reported to provide nutritional and immunological benefits individually. However, considering the complexity of the human diet, it is useful to determine how the combination of food ingredients such as rice bran and quercetin influences the human gut microbiota. Our study provides insights into how these ingredients influence microbiome composition alone and in combination in vitro. This will allow us to identify which species in the gut microbiome are responsible for biotransformation of these dietary ingredients.. Such information is helpful for the development of synbiotics to improve gut health and immunity.

Dietary inflammatory potential in relation to the gut microbiome: results from a cross-sectional study

“…Although in our study higher C. leptum was observed in healthy individuals with a more pro-inflammatory diet, this cross-sectional association was attenuated with adjustment for age and BMI. A. intestini, previously recovered from various human clinical samples of hospitalised patients (53) , appears to be responsive to supplementation with quercetin and partially hydrolysed guar gum in human faecal samples (54,55) and is positively associated with LPS-stimulated TNFα production (56) . This is generally consistent with our study finding of higher A. intestini in the most pro-inflammatory diet group and its positive correlation with circulating PAI-1, a proinflammatory marker closely associated with obesity, type-2 diabetes and CVD risk (57) .…”

Potential Implications of Citrulline and Quercetin on Gut Functioning of Monogastric Animals and Humans: A Comprehensive Review

“…Additionally, studies have combined polyphenols such as resveratrol and quercetin widely for their health benefits, and their role in modulating the gut microbial ecosystem [2,28]. Combination of rice bran and quercetin altered gut microbiome composition and metabolites, such that there was a significant shift to enrich the proliferation of beneficial bacteria, while the population of opportunistic pathogens in the gut was reduced [195]. Quercetin and catechin combination was reported as a potential therapy for alleviating excessive adipose tissue inflammation, improving metabolic parameters related to insulin sensitivity, and regulating cell redox status to exert anti-inflammatory actions [196].…”

The Targeted Impact of Flavones on Obesity-Induced Inflammation and the Potential Synergistic Role in Cancer and the Gut Microbiota

“…Several flavonoids are shown to enrich beneficial bacterial abundance while reducing potential detrimental microbes in the human gut. Quercetin and resveratrol decreased the Enterobacteriaceae family and reduced the Firmicutes/Bacteroidetes ratio in the human gut, as shown through the 16S rRNA sequencing of fecal samples [226,227]. Diet supplementation with soy bars significantly enhances the abundance of beneficial Bifidobacterium bacteria in postmenopausal women, which results in increased lipid catabolism [228].…”