Association between functional lactase variants and a high abundance of Bifidobacterium in the gut of healthy Japanese people

Previous studies have shown that Japanese people exhibit a higher abundance of Bifidobacterium compared to people from other countries. Among the possible factors affecting the gut microbiota composition, an association of functional lactase gene variants with a higher abundance of Bifidobacterium in the gut has been proposed in some reports. However, no Japanese subjects were included in these studies. In this study, we investigated the possible contribution of functional lactase loci to the high abundance of Bifidobacterium in Japanese populations. Based on a data analysis assessing 1,068 healthy Japanese adults, a number of subjects is at least seven times greater than that reported in available online data. all subjects possessed CC genotype at rs4988235 and the GG at rs182549, which are associated with low lactase activity. We observed a positive correlation between dairy product intake and Bifidobacterium abundance in the gut. Considering previous reports, which revealed that four additional functional lactase loci, rs145946881, rs41380347, rs41525747 and rs869051967 (ss820486563), are also associated with low lactase activity in Japanese people, our findings imply the possible contribution of host genetic variation-associated low lactase activity to the high abundance of Bifidobacterium in the Japanese population.既往研究表明，与其他国家人群相比，日本人群的肠道双歧杆菌（Bifidobacterium）丰度更高。在影响肠道菌群组成的诸多潜在因素中，部分研究提出功能性乳糖酶基因变异与肠道双歧杆菌丰度升高存在关联，但此类研究均未纳入日本受试者。本研究旨在探究功能性乳糖酶基因座（lactase loci）对日本人群肠道双歧杆菌高丰度的潜在贡献。本研究针对1068名健康日本成年人展开数据分析，该样本量至少为现有公开在线数据报道的7倍。所有受试者均携带与低乳糖酶活性相关的rs4988235位点CC基因型及rs182549位点GG基因型。本研究观察到乳制品摄入量与肠道双歧杆菌丰度呈正相关。结合既往研究显示的另外4个与日本人群低乳糖酶活性相关的功能性乳糖酶基因座：rs145946881、rs41380347、rs41525747及rs869051967（ss820486563），本研究结果提示，宿主遗传变异介导的低乳糖酶活性可能是日本人群肠道双歧杆菌丰度升高的潜在原因。