Introduction. Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that affects the quality of life of numerous people worldwide. Gap statement. The therapeutic role of gut microbiota modulation in IBS remains controversial. Aim. We aimed to assess the efficacy of probiotics, prebiotics or synbiotics in patients with IBS. Methodology. We searched MEDLINE and EMBASE up to 1 August 2023, to identify the randomized, double-blind, placebo-controlled trials investigating the effectiveness of probiotics, prebiotics or synbiotics among patients with IBS. Pooled analyses of the effects of probiotics in relieving IBS symptoms were calculated using a random-effects model. Further subgroup analyses were performed by different genera, doses and duration of treatment. Results. Our final analysis included 52 trials involving 6289 IBS patients. Probiotics significantly increased the overall response rate (RR:1.64; P<0.00001), subjective relief rate (RR:1.50; P=0.0002) and abdominal pain relief rate (RR:1.69; P<0.00001). As for specific genera, mixed probiotics (RR:1.41; P=0.0001), Bifidobacterium (RR:1.76; P<0.00001), Lactobacillus (RR:1.97; P=0.0004) and Saccharomyces (RR:1.31; P=0.0004) markedly relieved IBS symptoms. Mixed probiotics (RR:1.31; P=0.005), Lactobacillus (RR:2.22; P=0.04) and Bifidobacterium (RR:1.62; P<0.0001) elevated patients’ subjective relief rate. Besides, probiotics effectively relieved the abdominal pain in IBS patients (RR:1.69; P<0.00001). Probiotics appeared to show a remarkable beneficial role at a dose of 109 c.f.u./day or above (RR:1.662; P<0.0001) and started to work at 4 weeks (RR 1.72; P<0.00001). Efficacy of prebiotics and synbiotics in IBS remained uncertain, due to the deficiency of available RCTs. Conclusions. Probiotics have a therapeutic role in IBS. However, the effect of different probiotics varies. The minimal effective dose of probiotics may be 109 c.f.u./day. With appropriate probiotic formula, the therapeutic effect can occur at 4 weeks. These data provide a basis for further research on the optimal probiotic therapy in IBS.

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益生菌、益生元和合生元对肠易激综合征的功效：随机、双盲、安慰剂对照试验的系统评价和荟萃分析

介绍。肠易激综合症（IBS）是一种常见的胃肠道疾病，影响全世界许多人的生活质量。差距声明。肠道微生物群调节对 IBS 的治疗作用仍存在争议。目的。我们的目的是评估益生菌、益生元或合生元对 IBS 患者的疗效。方法。我们检索了截至 2023 年 8 月 1 日的 MEDLINE 和 EMBASE，以确定研究益生菌、益生元或合生元在 IBS 患者中的有效性的随机、双盲、安慰剂对照试验。使用随机效应模型计算益生菌缓解 IBS 症状效果的汇总分析。按不同属、剂量和治疗持续时间进行进一步的亚组分析。结果。我们的最终分析包括 52 项试验，涉及 6289 名 IBS 患者。益生菌显着提高了总体缓解率（RR：1.64；P <0.00001）、主观缓解率（RR：1.50；P = 0.0002）和腹痛缓解率（RR：1.69；P <0.00001）。就具体属而言，混合益生菌（RR：1.41；P = 0.0001）、双歧杆菌（RR：1.76；P <0.00001）、乳酸菌（RR：1.97；P = 0.0004）和酵母菌（RR：1.31；P = 0.0004）显着缓解IBS症状。混合益生菌（RR：1.31；P = 0.005）、乳酸菌（RR：2.22；P = 0.04）和双歧杆菌（RR：1.62；P <0.0001）提高了患者的主观缓解率。此外，益生菌有效缓解IBS患者的腹痛（RR：1.69；P <0.00001）。益生菌在剂量为 10 9 cfu/天或以上时似乎显示出显着的有益作用（RR：1.662；P <0.0001），并在 4 周时开始发挥作用（RR 1.72；P <0.00001）。由于缺乏可用的随机对照试验，益生元和合生元对 IBS 的疗效仍不确定。结论。益生菌对 IBS 具有治疗作用。然而，不同的益生菌的效果各不相同。益生菌的最小有效剂量可能是10 9 cfu/天。采用合适的益生菌配方，4周即可发挥治疗效果。这些数据为进一步研究IBS最佳益生菌疗法奠定了基础。