Fucoxanthin is a non-provitamin A carotenoid contained in brown seaweeds. We found that it suppressed interleukin-17 secretion from CD4+ T cells under IL-17-producing T (Th17) cell development conditions. By evaluating T cell differentiation in vitro, fucoxanthin and its metabolite fucoxanthinol inhibited T cell differentiation into Th17 cells. This suggests that fucoxanthin can improve inflammatory diseases due to Th17 cells.
