Sulforaphane is a naturally occurring, potent antioxidant and anti-inflammatory compound, found in broccoli that is broken down and absorbed primarily in the gut. Sulforaphane has an established clinical safety profile and is effective in managing hypertension, and the vascular dysfunction that underlies preeclampsia. As sulforaphane would be consumed as a nutritional supplement primarily absorbed in the gut, there is the potential for sulforaphane to impact the gut microbiome. The human gut microbiome has been implicated in both health and disease. However, nutritional components such as prebiotics, have been shown to change microbial composition and improve outcomes for patients with metabolic diseases such as prediabetes and obesity. Therefore, we have screened the effect of sulforaphane on the growth of a panel of 47 common gastrointestinal bacterial isolates, in both rich media (YCFA) and media lacking thiamine and riboflavin. The 47 isolates were chosen as they represented the four main phyla, and the proportions of each, found in the human gastrointestinal microbiome; Firmicutes (24 strains), Bacteroidetes (10 strains), Proteobacteria (9 strains) and Actinobacteria (4 strains). From this group, 31 isolates showed significant changes in growth, with 12 showing significant changes in both media types. These isolates are members of the Firmicutes (6 isolates), Proteobacteria (5 isolates) and Bacteroidetes (1 isolate) phyla and contain 10 commensals and two pathogenic isolates. Further work will aim to investigate the metabolic changes that underpin these growth changes and determine if these bacteria are impacting the efficacy of sulforaphane or if sulforaphane is changing microbiome composition.