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Objectives Sulforaphane is a bioactive metabolite with anti-inflammatory activity that is derived from glucosinolates, which are highly abundant in cruciferous vegetables including broccoli sprouts. There have been limited studies to investigate a whole foods approach to increase sulforaphane levels with therapeutic effect and reduce inflammation. In the current study, using a mouse model of inflammatory bowel disease, we aimed to investigate the ability of steamed broccoli sprouts to ameliorate colitis and the role of the microbiota in mediating any effects. Methods C57BL/6J male mice were fed base diet or 5% steamed broccoli sprout diet for 2 weeks prior to induction of colitis with 2–3% DSS (5–7 days) and kept on their respective diets until sacrifice. Body weight and disease activity index scores were recorded daily, and histological assessment was performed on H&E sections of colon. Urine, feces, blood, and GI tract tissues and intestinal content were collected for LC-MS/MS quantification of sulforaphane and glucoraphanin. The 16S rRNA sequencing was performed to analyze gut microbiome. Germ-free mice were fed base diet or 5% steamed broccoli sprout diet for 2 weeks followed by treatment with 5 days of DSS to determine the role of gut microbiota in mediating the anti-inflammatory effects of the steamed broccoli sprout diet. Results We observed that despite inactivation of the plant myrosinase enzyme responsible for the generation of sulforaphane via steaming, measurable levels of sulforaphane were detectable in the colon tissue and feces of mice after ingestion of steamed broccoli sprouts. In addition, this preparation of broccoli sprouts was also capable of reducing chemically-induced colitis. This protective effect was dependent on the presence of an intact gut microbiota, highlighting an important role for the microbiota in the metabolism of cruciferous vegetables to generate bioactive metabolites and promote their anti-inflammatory effects. Conclusions Altogether, these results suggest that the incorporation of a steamed broccoli sprouts diet is a viable dietary intervention to complement current medical therapies for patients with inflammatory bowel disease. Funding Sources This work was supported by USDA-NIFA-AFRI Foundational Program [Grant No. 2018–67,017-27,520].

Inflammatory Bowel Diseases (IBD) are chronic conditions characterized by inflammation of the gastrointestinal tract that heavily burden daily life, result in surgery or other complications, and disrupt the gut microbiome. How IBD influences gut microbial ecology, especially biogeographic patterns of microbial location, and how the gut microbiota can use diet components and microbial metabolites to mediate disease, are still poorly understood. Many studies on diet and IBD in mice use a chemically induced ulcerative colitis model, despite the availability of an immune-modulated Crohn's Disease model. Interleukin-10-knockout (IL-10-ko) mice on a C57BL/6 background, beginning at age 4 or 7 weeks, were fed either a control diet or one containing 10% (w/w) raw broccoli sprouts which was high in the sprout-sourced anti-inflammatory sulforaphane. Diets began 7 days prior to inoculation with Helicobacter hepaticus, which triggers Crohn's-like symptoms in these immune-impaired mice, and ran for two additional weeks. Key findings of this study suggest that the broccoli sprout diet increases sulforaphane concentration in plasma; decreases weight stagnation, fecal blood, and diarrhea associated with enterocolitis; and increases microbiota richness in the gut, especially in younger mice. Sprout diets resulted in some anatomically specific bacterial communities in younger mice, and reduced the prevalence and abundance of potentially pathogenic or otherwise-commensal bacteria which trigger inflammation in the IL-10 deficient mouse, for example, Escherichia coli and Helicobacter. Overall, the IL-10-ko mouse model is responsive to a raw broccoli sprout diet and represents an opportunity for more diet-host-microbiome research. A diet containing 10% raw broccoli sprouts increased the plasma concentration of the anti-inflammatory compound sulforaphane, and may be protective against negative disease characteristics of Helicobacter-induced enterocolitis in interleukin-10 knockout mice, including weight loss or stagnation, fecal blood, and diarrhea. Younger mice responded more strongly to the diet intervention, and resulted in increased gut bacterial community richness and bacterial community similarity by diet treatment and some anatomical locations in the gut, even in mice with adverse reactions to gut microbiota and a relatively short time in which they had been able to recruit them. To our knowledge, IL-10-ko mice have not previously been used to investigate the interactions of host, microbiota, and broccoli, broccoli sprouts, or broccoli bioactives in resolving symptoms of CD.

Inflammatory Bowel Diseases (IBD) are devastating conditions of the gastrointestinal tract with limited treatments, and dietary intervention may be effective, affordable, and safe for managing symptoms. Ongoing research has identified inactive compounds in broccoli sprouts, glucoraphanin, and indicated that mammalian gut microbiota play a role in metabolizing it to the anti-inflammatory sulforaphane. The biogeographic location of participating microbiota and how that affects anti-inflammatory benefits to the host is unknown. We fed specific pathogen free C57BL/6 mice either a control diet or a 10% steamed broccoli sprout diet, and gave a three-cycle regimen of 2.5% dextran sodium sulfate (DSS) in drinking water over a 40-day experiment to simulate chronic, relapsing ulcerative colitis. We monitored body weight, fecal characteristics, fecal lipocalin, and bacterial communities from the digesta and epithelium in the jejunum, cecum, and colon. Mice fed the broccoli sprout diet while receiving DSS performed better than mice fed the control diet while receiving DSS for all disease parameters, including significantly more weight gain, lower Disease Activity Index scores, and higher bacterial richness in all gut locations. Bacterial communities were assorted by gut location except in the mice receiving the control diet and DSS treatment. Importantly, our results suggested that broccoli sprout feeding completely abrogated the effects of DSS on gut microbiota, as bacterial communities were similar between mice receiving broccoli sprouts with and without DSS. Collectively, these results strongly support the protective effect of steamed broccoli sprouts against gut microbiota dysbiosis and development of colitis induced by DSS.