Broccoli consumption alters microbial diversity, metatranscriptome and host transcriptome in mice fed a Total Western Diet

Authors: Pletsch, Elizabeth; Smith, Allen; Ragonese, Jack; Narrowe, Adrienne; Cheung, Lumei; Chen, Celine; Wang, Thomas; Dawson, Harry

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2025
Publication Date: 8/1/2025
Citation: Pletsch, E.A., Smith, A.D., Ragonese, J.S., Narrowe, A.B., Cheung, L., Chen, C.T., Wang, T.T., Dawson, H.D. 2025. Broccoli consumption alters microbial diversity, metatranscriptome and host transcriptome in mice fed a Total Western Diet. Journal of Nutrition. 155(8):2475-2770. https://doi.org/10.1016/j.tjnut.2025.05.041.
DOI: https://doi.org/10.1016/j.tjnut.2025.05.041

Interpretive Summary: The Dietary Guidelines for Americans recommends individuals consume at least 2 ½ cup equivalents of vegetables per day. Broccoli is a commonly consumed cruciferous vegetable and is associated with reduced risk of chronic disease and improved immune function that may be related to changes in the gut microbiome. Previous animal studies have tested the beneficial health effects of broccoli, but it has not always been translatable to typical human intake levels or diet. In this study, mice were fed a Western-style diet for six weeks, followed by supplementation of increasing levels of broccoli powder for three weeks. We found that broccoli increased bacterial diversity and promoted expression of genes by bacteria that were associated with carbohydrate metabolism and production of certain short chain fatty acids. These pathways are important for providing the body with beneficial nutrients and compounds related to intestinal health. We also observed broccoli -mediated activation of an immune regulatory pathway in the host. These findings show that consumption of a broccoli-supplemented TWD induces changes in the gut microbiome, host and microbial gene expression that affect immune health and inflammation in the gut at levels that are achievable in the human diet.

Technical Abstract: Background: Cruciferous vegetables (CVs) are a source of dietary fiber and phytochemicals that alter the microbiome in animals and humans. Constituent cruciferous vegetable compounds, such as glucosinolates, have demonstrated anti-inflammatory properties in animal models, though often using doses and basal diets that are not relevant to humans. The mechanism(s) is unclear, but the gut microbiota may metabolize these compounds into bioactive molecules that influence immune pathways. Objectives: We investigated the effects of broccoli powder (BP)-supplemented total Western diet (TWD) on changes in the gut microbiome, the host transcriptome, and the metatranscriptome at levels relevant to the human diet to understand how these changes affect metabolic and immune functions. Methods: C57BL/6 male mice (n ¼ 40) were fed a TWD control diet for 6 wk followed by supplementation with 0%, 0.5%, 1%, or 2.5% BP (reflecting a human intake from ¼–1 cup/d) for 3 wk. Microbial communities from cecal contents were taxonomically profiled using 16S ribosomal ribonucleic acid amplicon and shotgun metagenomic sequencing, and metatranscriptomics was used to assess the functionality of the microbial communities. The host cecal transcriptome was also assessed. Results: ß-diversity was significantly higher (P ¼ 1.20  10–3) for mice fed the 2.5% BP diet compared to the control group at the species level. Lachnospiraceae MD335 was significantly more abundant in mice fed higher levels of broccoli, and analysis of bacterial ribonucleic acid transcripts indicated a dose-dependent increase in transcription of genes associated with butyrate and acetate production, plant cell wall degradation, and carbohydrate utilization. Activation of the aryl hydrocarbon receptor pathway in the cecum was evident. Conclusions: Consumption of a broccoli-supplemented TWD induces changes in the gut microbiome, host, and microbial gene expression that affect immune health and inflammation in the gut at levels that are achievable in the human diet.