The gut microbiota of healthy individuals remains resilient in response to the consumption of various dietary fibers

This study focuses on the resilience of gut microbiota during a five-month multi-interventional nutrition trial. The modulatory effects of beta-glucan, rye bran and two dietary fiber mixtures on the fecal pH and compositional changes of the microbiome of healthy subjects were studied. To analyze the stability of intestinal microbiota, we collected an extensive dataset of sequential fecal samples (23-29 from each participant) during a week of the base, beta-glucan consumption and wash-out periods accompanied by the collection of daily food diary data. Microbiota analyses were also conducted after the end of each fiber intake and wash-out period, along with measurements of fecal organic acids and pH. Based on the dominant bacterial taxa, two prevalent microbiota types were identified. The Prevotella-type microbiota responded more to the tested dietary fibers, while the Bacteroides-type microbiota was the least affected. Three microbiota types could not be clustered and behaved differently. Although we noted individual effects of definite fibers on participants' gut microbiota and metabolic profile, relative abundances of bacteria remained stable in the base period (z-scores -2.2 to 2.3). In most cases, the bacterial abundances of the final samples remained within the normal fluctuation range stressing out the resilience of healthy microbiota. The pH of all fecal samples varied between 6.1 and 8.3 and was associated with the concentration of organic acids and microbial composition. The effect of dietary fibers on the metabolism of fecal microbiota clearly depended on the individual microbiota type. Combining the analysis of gut microbiota with knowledge of the properties of dietary fibers would provide a powerful strategy for nutrition guidance and disease prevention.

本研究聚焦于为期五个月的多干预营养试验期间肠道菌群（gut microbiota）的恢复弹性。本研究探讨了β-葡聚糖（beta-glucan）、黑麦麸皮（rye bran）以及两种膳食纤维混合物（dietary fiber mixtures）对健康受试者粪便pH值与微生物组（microbiome）组成变化的调控作用。为分析肠道菌群的稳定性，研究团队在基线期、β-葡聚糖摄入期及洗脱期的一周内，收集了每名受试者的多份连续粪便样本（每人23~29份），同时收集每日饮食日记数据以构建大规模数据集。在每一轮纤维摄入及洗脱期结束后，研究团队均开展了菌群分析，并同步测定粪便有机酸含量与pH值。基于优势细菌类群，本研究共鉴定出两种优势菌群型。普氏菌型（Prevotella-type）菌群对受试膳食纤维的响应更为显著，而拟杆菌型（Bacteroides-type）菌群受影响程度最低；另有三类菌群无法被聚类，且呈现出差异化的行为特征。尽管研究观察到特定纤维对受试者肠道菌群及代谢谱存在个体效应，但基线期内细菌的相对丰度保持稳定（z评分范围为-2.2至2.3）。多数情况下，最终样本的细菌丰度仍处于正常波动区间，这凸显了健康肠道菌群的恢复弹性。所有粪便样本的pH值介于6.1至8.3之间，且与有机酸浓度及微生物组成密切相关。膳食纤维对粪便菌群代谢的影响，显然取决于个体的菌群类型。将肠道菌群分析与膳食纤维特性的认知相结合，可为营养指导与疾病预防提供强有力的策略。