Effects of cumin, coriander, and sichuan pepper on microbiota and the antioxidant capacities of human faecal cultures

Abstract

Spices have been reported to have several health-promoting effects. In this study, we investigated the effects of cumin seeds (CM), coriander seeds (CR), and Sichuan pepper (HJ) on human gut microbiota using human stool samples from healthy volunteers. The samples were incubated with or without addition of these spices, and the microbiota were analysed using 16S rRNA (V4) gene amplicon sequencing. After anaerobic fermentation for 24 h, pH was slightly lowered under HJ addition, although this varied across individuals. Acetate, propionate, and total short chain fatty acid levels increased under CM and CR addition. Indole content was low in cultures with HJ. Fermentation of the faecal samples increased in vitro superoxide anion (O2-) radical-scavenging and Fe-reducing capacities under CM and CR addition, although antioxidant capacities were still higher in cultures with HJ. Genera regarded as butyrate producers (Faecalibacterium and Roseburia) were high in HJ cultures, but the genera, species, and amplicon sequence variants of butyrate producers were different across individuals. In contrast, Enterobacteriaceae presence was lowered with CM and HJ addition. These results suggest that compounds contained in the investigated spices, particularly in HJ, which reach the human colon affect the gut microbiota. Further studies on the mechanisms of the interaction between spice components and spice-responsive gut indigenous bacteria, both desirable (butyrate producers) and undesirable (inflammation-related commensals), are needed.