US Army Research Institute of Environmental Medicine, Natick, MA, USA.
Oak Ride Institute of Science and Education, Belcamp, MD, USA.
Adv Nutr. 2022 Dec 22;13(6):2277-2295. doi: 10.1093/advances/nmac086.
The impact of gut microbiota-targeted interventions on the incidence, duration, and severity of respiratory tract infections (RTIs) in nonelderly adults, and factors moderating any such effects, are unclear. This systematic review and meta-analysis aimed to determine the effects of orally ingested probiotics, prebiotics, and synbiotics compared with placebo on RTI incidence, duration, and severity in nonelderly adults, and to identify potential sources of heterogeneity. Studies were identified by searching CENTRAL, PubMed, Scopus, and Web of Science up to December 2021. English-language, peer-reviewed publications of randomized, placebo-controlled studies that tested an orally ingested probiotic, prebiotic, or synbiotic intervention of any dose for ≥1 wk in adults aged 18-65 y were included. Results were synthesized using intention-to-treat and per-protocol random-effects meta-analysis. Heterogeneity was explored by subgroup meta-analysis and meta-regression. Risk of bias was assessed using the Cochrane risk-of-bias assessment tool for randomized trials version 2 (RoB2). Forty-two manuscripts reporting effects of probiotics (n = 38), prebiotics (n = 2), synbiotics (n = 1) or multiple -biotic types (n = 1) were identified (n = 9179 subjects). Probiotics reduced the risk of experiencing ≥1 RTI (relative risk = 0.91; 95% CI: 0.84, 0.98; P = 0.01), and total days (rate ratio = 0.77; 95% CI: 0.71, 0.83; P < 0.001), duration (Hedges' g = -0.23; 95% CI: -0.39, -0.08; P = 0.004), and severity (Hedges' g = -0.16; 95% CI: -0.29, -0.03; P = 0.02) of RTIs. Effects were relatively consistent across different strain combinations, doses, and durations, although reductions in RTI duration were larger with fermented dairy as the delivery matrix, and beneficial effects of probiotics were not observed in physically active populations. Overall risk of bias was rated as "some concerns" for most studies. In conclusion, orally ingested probiotics, relative to placebo, modestly reduce the incidence, duration, and severity of RTIs in nonelderly adults. Physical activity and delivery matrix may moderate some of these effects. Whether prebiotic and synbiotic interventions confer similar protection remains unclear due to few relevant studies. This trial was registered at https://www.crd.york.ac.uk/prospero/ as CRD42020220213.
肠道微生物群靶向干预措施对非老年成年人呼吸道感染（RTIs）的发生率、持续时间和严重程度的影响，以及调节这些影响的因素尚不清楚。本系统评价和荟萃分析旨在确定口服益生菌、益生元和合生菌与安慰剂相比，对非老年成年人 RTI 发生率、持续时间和严重程度的影响，并确定潜在的异质性来源。通过检索 CENTRAL、PubMed、Scopus 和 Web of Science，截至 2021 年 12 月，确定了研究。纳入了英语同行评议的随机对照研究出版物，这些研究测试了口服益生菌、益生元或合生菌干预措施，剂量≥1 周，用于 18-65 岁成年人。使用意向治疗和按方案随机效应荟萃分析综合结果。通过亚组荟萃分析和荟萃回归探索异质性。使用 Cochrane 随机试验偏倚评估工具版本 2（RoB2）评估偏倚风险。确定了 42 篇报告益生菌（n=38）、益生元（n=2）、合生菌（n=1）或多种生物类型（n=1）影响的手稿（n=9179 名受试者）。益生菌降低了经历≥1 次 RTI 的风险（相对风险=0.91；95%CI：0.84，0.98；P=0.01），总天数（率比=0.77；95%CI：0.71，0.83；P<0.001）、持续时间（Hedges'g=-0.23；95%CI：-0.39，-0.08；P=0.004）和严重程度（Hedges'g=-0.16；95%CI：-0.29，-0.03；P=0.02）。尽管在活跃人群中没有观察到益生菌的有益效果，但不同的菌株组合、剂量和持续时间的效果相对一致，发酵乳制品作为传递基质可降低 RTI 持续时间。总体而言，大多数研究的偏倚风险被评为“存在一些关注”。总之，与安慰剂相比，口服益生菌可适度降低非老年成年人 RTI 的发生率、持续时间和严重程度。身体活动和传递基质可能会调节其中的一些影响。由于相关研究较少，因此预生物和合生菌干预措施是否具有类似的保护作用尚不清楚。该试验在 https://www.crd.york.ac.uk/prospero/ 上注册为 CRD42020220213。
