R&D Unit, Mitsui Norin Co., Ltd.
Chiyoda Paramedical Care Clinic.
J Nutr Sci Vitaminol (Tokyo). 2023;69(5):326-339. doi: 10.3177/jnsv.69.326.
We previously reported that black tea consumption for 12 wk reduced the risk of acute upper respiratory tract inflammation, and improved secretory capacity in individuals with low salivary SIgA levels (Tanaka Y et al. 2021. Jpn Pharmacol Ther 49: 273-288). These results suggested that habitual black tea consumption improves mucosal immunity. Therefore, in this study we evaluated the effect of black tea intake on gut microbiota, which is known to be involved in mucosal immunity, by analyzing the bacterial flora and the short-chain fatty acids (SCFAs) concentration of feces collected during the above clinical study. The clinical design was a randomized, single-blind, parallel-group, placebo-controlled study with 72 healthy Japanese adult males and females, who consumed three cups of black tea (Black Tea Polymerized Polyphenols 76.2 mg per day) or placebo per day for 12 wk. In all subjects intake of black tea significantly increased abundance of Prevotella and decreased fecal acetic acid concentration. Particularly in the subjects with low salivary SIgA levels, the change over time of total bacteria, Prevotella, and butyrate-producing bacteria, which are involved in normalizing immune function, were higher in the black tea group than in the placebo group. In subjects with low abundance of Flavonifractor plautii a butyrate-producing bacteria, black tea consumption significantly increased salivary SIgA concentration and the absolute number of Flavonifractor plautii. In conclusion, our results suggest that improvement of mucosal immunity via an increase in butyrate-producing bacteria in the gut may partly contribute to the suppressive effect of black tea consumption on acute upper respiratory tract inflammation observed in our previous report.
我们之前报道过，饮用红茶 12 周可降低急性上呼吸道炎症的风险，并改善唾液分泌型免疫球蛋白 A（sIgA）水平较低人群的分泌能力（Tanaka Y 等人，2021 年。日本药理学与治疗学 49：273-288）。这些结果表明，习惯性饮用红茶可改善黏膜免疫。因此，在这项研究中，我们通过分析在上述临床研究中收集的粪便细菌菌群和短链脂肪酸（SCFA）浓度，评估了红茶摄入对肠道微生物群的影响，已知肠道微生物群与黏膜免疫有关。临床设计为一项随机、单盲、平行组、安慰剂对照研究，纳入 72 名健康的日本成年男性和女性，他们每天饮用三杯红茶（每天摄入 76.2 毫克红茶聚合多酚）或安慰剂，持续 12 周。在所有受试者中，红茶的摄入显著增加了普雷沃氏菌的丰度，并降低了粪便乙酸浓度。特别是在唾液 sIgA 水平较低的受试者中，与安慰剂组相比，涉及免疫功能正常化的总细菌、普雷沃氏菌和产生丁酸的细菌的时间变化在红茶组中更高。在丰度较低的产丁酸菌 Flavonifractor plautii 的受试者中，红茶的摄入显著增加了唾液 sIgA 浓度和 Flavonifractor plautii 的绝对数量。总之，我们的结果表明，通过增加肠道中产丁酸菌来改善黏膜免疫可能部分有助于解释我们之前报告中观察到的红茶摄入对急性上呼吸道炎症的抑制作用。
