<i>Cha</i>-<i>Koji</i>, comprising green tea leaves fermented with <i>Aspergillus luchuensis var kawachii kitahara</i>, increases regulatory T cell production in mice and humans
<p>Green tea leaves fermented with <i>Aspergillus luchuensis var kawachii kitahara</i> (<i>Cha</i>-<i>Koji</i>) are a health food containing live <i>A. luchuensis</i>. In this study, we examined the effects of <i>Cha</i>-<i>Koji</i> on the immune system and the enteric environment. First, we designed a clinical trial; after ingesting <i>Cha</i>-<i>Koji</i> daily for 28 days, blood parameters and the fecal composition of the participants were analyzed. Similarly, mice were administered (oral administration) with <i>Cha</i>-<i>Koji</i> suspension or its vehicle for 14 days. Thereafter, both humans and mice were examined by analyzing their immune cell phenotypes and intestinal microbiota. Regulatory T cell (Treg) numbers were significantly increased after administering <i>Cha</i>-<i>Koji</i>. An increase of <i>Clostridium</i> subcluster XIVa, that were known to be rich in butyrate-producing bacterium, was observed in human feces, but not in mice. These results suggest that <i>Cha</i>-<i>Koji</i> has the ability to increase Treg production in both humans and mice, irrespective of the presence of enteric butyrate.</p> <p>“<i>Cha</i>-<i>Koji</i>” increases regulatory T cells in mice and humans.</p
