The impact of black raspberry, blueberry, and blackberry phenolic and volatile extracts on fecal microbiota composition of individuals with normal weight and overweight/obesity

The impact of phenolic and volatile extracts from black raspberries, blueberries, and blackberries on human fecal microbial composition was determined via in vitro fermentation of fecal samples from normal-weight and overweight/obese individuals. Fecal samples were incubated with treatments and collected at 0 and 24 h. Microbial composition was analyzed by 16S rRNA amplicon sequencing. Normal-weight individuals had more Firmicutes, Faecalibacterium and Oscillospira, and overweight/obese individuals had more Bacteroidetes and Coprococcus at 0 h. After 24 h, the relative abundance of Verrucomicrobia, Oscillospira, and Akkermansia increased, while that of Bacteroidetes, Actinobacteria, Roseburia , and Ruminococcus decreased in all samples. However, there was no significant modulating effect of three berry phenolic and volatile extracts compared to the control at 24 h. Considering the limitations of this study, further research with a longer treatment duration of higher concentration while controlling individuals' diet would be needed to determine the impact of berry phenolics and volatiles on gut microbiota composition.