Several studies have indicated that weight-reduction plan plays a vital role in maintaining and altering the gut microbiome. In reality, the quantity of fat, protein, phytoestrogens, polyphenols, and carbohydrates consumed by a person influences microbial diversity. Gut microbial population and abundance affect the degrees of metabolites, resembling acetate, butyrate, and propionate, which affect physiological functions.
A recent Scientific Reports study investigates how grapes influence the human microbiome.
Study: Influence of grape consumption on the human microbiome. Image Credit: Andrew Hagan / Shutterstock.com
In the USA alone, six million tons of grapes are produced yearly. Several studies have indicated that grape consumption manifests an array of responses related to inflammation, gastrointestinal health, urinary bladder function, vision, atherosclerosis, and atherosclerosis. Moreover, mouse models have revealed that dietary grapes have pronounced effects on gene expression that influences several diseases within the liver or brain.
Over 1,600 phytochemical compounds have been identified in grapes which, alone or together with other compounds, affect different physiological processes. Probably the most common chemical constituent of a grape is resveratrol, which has been studied extensively.
One previous study has shown that human intestinal microbiota treated with total grape seed led to a change in short-chain fatty acids (SCFAs) profile and relevant microbial populations. Mice subjected to a high-fat weight-reduction plan together with grape powder exhibited a rise in microbial populations that synthesize butyrate.
When the grape powder was added to a normal murine weight-reduction plan, urinary excretion of the gut microbiota metabolites 5-hydroxyindole, gluconic acid, glyceric acid, myo-inositol and 4-hydroxyphenylacetic acid were attenuated. In contrast, a rise in certain metabolites resembling scyllo-inositol, xylitol, 5-hydroxyindole, gluconic acid, 2′-deoxyribonic acid, and mannitol was observed.
In humans, grape consumption can result in a rise within the alpha-diversity index of the gut microbiome. Reduced total bile acid and levels of cholesterol has also been correlated with grape consumption.
Concerning the study
A complete of forty healthy, free-living human participants were recruited on this trial which was conducted for 2 months. All participants were subjected to two-weeks of a restricted weight-reduction plan (Day 15), two-weeks of a restricted weight-reduction plan supplemented with the equivalent of three servings of grapes per day (Day 30), and a one-month washout period (Day 60).
Subsequently, plasma, urine, and fecal samples were collected from each participant. Out of the forty participants initially recruited for the study, only twenty-nine individuals accomplished the trial.
Alpha-diversity reflects the richness and relative abundance of microbial population within the gut. In the present study, no alterations in alpha diversity were observed amongst male participants between 24 and 44 years of age. Nonetheless, female participants between 29 and 39 years of age exhibited a difference in alpha diversity on Day 60 as in comparison with Day 15.
Principal component analyses (PCA) and principal coordinate analyses (PCoA) were used to research beta diversity. Based on cluster evaluation, no significant differences in beta diversity were observed within the study period, regardless of gender-based subgroup evaluation.
Common microbial species found on Day 15, 30, and 60 were Faecalibacterium prausnitzi,i Eubacterium rectale, Prevotella copri, Alistipes finegoldii, Fusicatenibacter saccharivorans, Bacteroides vulgatus, Alistipes putredinis, Bacteroides stercoris, Parabacteroides merdae, Bacteroides uniformis, Bifidobacterium adolescentis, Bacteroides coprocola, and Collinsella aerofaciens.
Microbial taxonomic analyses revealed significant microbial alterations at every time point. On Day 30, an increased level of Streptococcus thermophiles was observed.
Previous studies have revealed that this bacterium produces lactic acid within the gut and is taken into account a probiotic. As well as, a decrease in Holdemania spp. was observed. An analogous microbial profile was recorded in those under a vegetarian weight-reduction plan.
At Day 30, a rise within the abundance of Holdemania was noted; nonetheless, no change in Streptococcus thermophiles occurred. At Day 60, a major increase in the extent of organisms related to the production of metabolites was observed. These findings indicate a delayed gut microbial response to grape consumption, as no microbial alterations were found on Day 15.
Grape consumption manifested changes in certain enzyme levels. For instance, a rise in catechol 2,3-dioxygenase level was observed, which causes metabolic cleansing. As well as, a decrease within the(3S)-malyl-CoA thioesterase was observed, which influences the glyoxylate cycle of microorganisms.
As in comparison with day 15, a major increase in error-prone DNA polymerase was observed on Days 30 and 60. These findings indicate a delayed effect of grape consumption on enzyme levels.
As in comparison with Day 15, elevated levels of cysteine peptidases and decreased levels of ABC transporters and Narl family were observed on Day 30. Moreover, as in comparison with Day 30, a rise in oxidoreductases, ABC Transporters, and Nonribosomal peptide synthetase (NRPS) was reported on Day 60.
The present study revealed that grape consumption doesn’t alter the eubiotic state of the microbiome that prevails in healthy participants. Nevertheless, grape consumption alters the taxonomic composition of the microbiome, KEGG pathways, enzyme levels, and metabolic profile. In the longer term, more research is required to know whether these changes have broader health advantages.
- Dave, A., Beyoglu, D., Park, E., et al. (2023) Influence of grape consumption on the human microbiome. Scientific Reports 13(7706). doi:10.1038/s41598-023-34813-5