Molecular hydrogen as a potential mediator of the antitumor effect of inulin consumption.

Abstract

Both inulin and molecular hydrogen (H2) have demonstrated antitumor activity in preclinical and clinical settings. Because H2 is a principal byproduct of inulin fermentation by gut microbiota, this study investigated whether H2 mediates the antitumor properties of inulin. Researchers first characterized the H2 exposure profile in mice following inulin gavage and designed an inhalation protocol to replicate that profile. Over a two-week period, daily inulin administration and the corresponding H2 inhalation regimen were compared for their effects on circulating immunity and on implanted melanoma growth. Both interventions produced comparable increases in circulating CD4+ and CD8+ T lymphocytes and similarly suppressed melanoma tumor growth. Tumor infiltration by T cells was also assessed. The findings support a model in which H2 generated by microbial fermentation of inulin crosses the intestinal barrier and activates immunosurveillance mechanisms responsible for antitumor activity.

Mechanism

H2 produced by gut microbial fermentation of inulin is proposed to diffuse across the intestinal barrier, subsequently activating CD4+ and CD8+ T cell-mediated immunosurveillance that suppresses tumor growth.