Impact of low-dose GOS on Bifidobacterium abundance in healthy women.. A double-blind intervention trial in healthy women demonstrates the beneficial impact on Bifidobacterium with low dosages of prebiotic galacto-oligosaccharides

Galacto-oligosaccharides (GOS) are well-substantiated prebiotic substrates. Multiple studies have demonstrated a positive impact of GOS on gut microbiota composition and activity, sofar mainly related to Bifidobacterium. However, data on the beneficial impact at lower dosages in a healthy female population are limited. The primary aim of the current study was to reveal the effect of low dosages (1.3 and 2.0g) of GOS on fecal Bifidobacterium abundance in healthy women. Other outcomes included the effect of low dosage of GOS on overall fecal microbiota composition and on self-perceived GI comfort, sleep quality and mental wellbeing.Method: Eighty-eight healthy women (42-70 y, BMI 18.7-30 kg/m 2 ) were included in this randomized, parallel, double-blind study of 6 weeks. The participants were stratified for fiber intake, BMI and age and randomized to consume either 1.3 or 2.0g of GOS per day for 3 weeks after a control period of 3 weeks without any intervention. Fecal samples were collected for shotgun metagenomics sequencing at the start (t=-3) and end (t=0) of the control period and at the end of the intervention period (t=3). Self-perceived gut comfort, sleep quality, and mental wellbeing were assessed weekly. Hierarchical clustering of principal components was applied to data collected from study participants.The relative abundance of Bifidobacterium in feces increased significantly after 3 weeks of daily consumption of both 1.3g (p<0.01) and 2.0g GOS (p<0.01). This was accompanied by a significant shift in the overall microbiota composition for the dosage of 2.0g GOS (p<0.01). Participants that showed a larger increase in Bifidobacterium in the intervention period compared to the change in Bifidobacterium in the control period, defined as responders, showed a significant overall difference in initial fecal microbiota composition as compared to non-responders (p=0.04) and a trend towards lower baseline levels of Bifidobacterium in responders (p=0.10).Daily consumption of a low dose of GOS can lead to an increase in the relative abundance of Bifidobacterium in feces of healthy women. Additionally, with 2.0g GOS, the enrichment of Bifidobacterium is accompanied with a shift in the overall microbiota composition.The study was registered at clinicaltrials.gov, identifier NCT05762965.

低聚半乳糖（Galacto-oligosaccharides, GOS）是被广泛证实的益生元底物。多项研究已证实GOS对肠道菌群组成与活性具有积极影响，迄今为止相关研究主要集中于双歧杆菌属（Bifidobacterium）。然而，针对健康女性群体采用低剂量GOS所产生的有益影响的相关数据仍较为有限。
本研究的首要目的为探究低剂量（1.3g与2.0g）GOS对健康女性粪便中双歧杆菌相对丰度的影响。其余研究结局则包括低剂量GOS对整体粪便菌群组成的影响，以及受试者自我感知的胃肠道舒适度、睡眠质量与心理健康状态。
方法：本研究为一项为期6周的随机平行双盲试验，共纳入88名健康女性（年龄42~70岁，体重指数18.7~30 kg/m²）。研究人员按照膳食纤维摄入量、体重指数与年龄对受试者进行分层，随后将其随机分组，在为期3周的基线对照期（无任何干预措施）结束后，两组受试者每日分别摄入1.3g或2.0g GOS，持续干预3周。分别在基线对照期开始（t=-3）与结束（t=0）时，以及干预期结束（t=3）时采集粪便样本，用于鸟枪宏基因组测序（shotgun metagenomics sequencing）。每周对受试者自我感知的胃肠道舒适度、睡眠质量与心理健康状态进行评估。对受试者的采集数据采用主成分分层聚类分析方法进行处理。
每日摄入1.3g与2.0g GOS持续3周后，受试者粪便中的双歧杆菌相对丰度均显著升高（1.3g组：p<0.01；2.0g组：p<0.01）。摄入2.0g GOS的受试者同时伴随整体粪便菌群组成发生显著改变（p<0.01）。将干预期内双歧杆菌丰度增幅较基线对照期变化更大的受试者定义为应答者，结果显示，应答者与非应答者的初始粪便菌群组成存在显著差异（p=0.04），且应答者的基线双歧杆菌水平呈低于非应答者的趋势（p=0.10）。
每日摄入低剂量GOS可使健康女性粪便中的双歧杆菌相对丰度升高。此外，摄入2.0g GOS时，双歧杆菌丰度升高的同时伴随整体粪便菌群组成的改变。
本研究已在ClinicalTrials.gov注册，注册号为NCT05762965。