A 14-Day Double-Blind, Randomized, Controlled Cross-Over Intervention Study With Anti-bacterial Benzyl Isothiocyanate From Nasturtium (Tropaeolum majus) on Human Gut Microbiome and Host Defense

Abstract

Despite substantial heterogeneity of studies, there is evidence that antibiotics commonly used in primary care influence the composition of the gastrointestinal microbiota in terms of changing the composition and/or diversity. Benzyl isothiocyanate (BITC) from the food and medicinal plant nasturtium (Tropaeolum majus) is known for its antimicrobial activity and is used for the treatment against infections of the draining urinary tract and upper respiratory tract. Against this background, we raised the question whether 14 d nasturtium intervention (3 g daily, N=30 healthy females) could also impact the normal gut microbiota composition. Spot urinary BITC excretion highly correlated with a weak, but significant antibacterial effect against Escherichia coli. A significant increase in human beta defensin 1 as parameter for host defense was seen in urine and exhaled breath condensate (EBC) upon verum intervention. Pre-to-post analysis revealed that mean gut microbiome composition did not significantly differ between groups, nor did circulating serum metabolome. On an individual level, partly large changes were observed between sampling points, though. Explorative Spearman rank correlation analysis in subgroups revealed associations between gut microbiota and the circulating metabolome, as well as between changes in blood markers and bacterial gut species.