Effects of in-vitro metabolism of a broccoli-leachate, glucosinolates, and S-methylcysteine sulphoxide on the human faecal microbiome

Kellingray L,Le Gall G,Doleman JF,Narbad A,Mithen RF. (2020)

European Journal of Nutrition

Brassica are an important food-source worldwide, and are characterised by the presence of compounds called glucosinolates. Studies indicate that the glucosinolate derived bioactive metabolite sulforaphane can elicit chemoprotective benefits on human cells. Glucosinolates can be metabolised in vivo by members of the human gut microbiome, although the prevalence of this activity is unclear. Brassica and Allium plants also contain S-methylcysteine sulphoxide (SMCSO), that may provide additional health benefits but its metabolism by gut bacteria is not fully understood. We examined the effects of a broccoli leachate (BL) on the composition and function of human faecal microbiomes of five different participants. Bacterial isolates from these communities were also tested for their ability to metabolise both glucosinolates and SMCSO. Microbial communities cultured in BL media were observed to enhance the growth of lactic acid bacteria, such as lactobacilli, with a corresponding increase in the levels of lactate. Higher levels of short-chain fatty acids were detected in BL media compared with when the microbial communities were cultured in the presence of glucose. Members of Escherichia isolated from these faecal communities were found to metabolise glucosinolates and SMCSO to their reduced analogues. This study emphasizes that the composition of the human gut microbiome can be modified by diet, leading to the production of bacterial metabolites or the biotransformation of dietary compounds. These compounds may be utilised by members of the microbiome, potentially conferring health benefits to the host.

European Journal of Nutrition

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