Probiotics Research

Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials

Asad A et al. • Nutrition reviews (2025)

Probiotics showed substantial reductions in depression symptoms and moderate reductions in anxiety symptoms.

• Probiotics demonstrated a significant reduction in depression symptoms (SMD: -0.96; 95% CI: -1.31, -0.61) and a moderate reduction in anxiety symptoms (SMD: -0.59; 95% CI: -0.98, -0.19).
• Prebiotics did not show a significant effect on depression (SMD: -0.28; 95% CI: -0.61, 0.04).
• High heterogeneity was observed across studies, and subgroup analyses indicated that study duration and probiotic formulations contributed to the variation in effect sizes.

Probiotics in the non-surgical treatment of periodontitis: a systematic review and network meta-analysis

Mendonça CD et al. • BMC oral health (2024)

This meta-analysis examined the effects of Probiotics.

• Network meta-analysis revealed significant mean differences in PPD for nine probiotic interventions, CAL for eighteen interventions, and BOP for eight interventions, with Lactobacillus demonstrating the most substantial effects.
• Combining PMPR with probiotics as adjuvants to subgingival instrumentation may be more effective in improving PPD and CAL.
• Lactobacillus emerged as the most comprehensive and effective among the studied probiotic.© 2024.

The use of probiotics and prebiotics in decolonizing pathogenic bacteria from the gut; a systematic review and meta-analysis of clinical outcomes

Rahman MN et al. • Gut microbes (2024)

Protocol registration: PROSPERO (ID = CRD42021276045).

• This review aims to analyze available evidence from human-controlled trials to determine the effect size of probiotic interventions in decolonizing AMR pathogenic bacteria from the gut.
• The persistence of pathogenic bacteria after treatment was 22%(probiotics) and 30.8%(placebo).
• The pooled odds ratio was 0.59(95% CI:0.43-0.81), favoring probiotics with moderate certainty (p = 0.0001) and low heterogeneity (I2 = 49.2%, p = 0.0001).

Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials

Liu Y et al. • Frontiers in Immunology (2023)

Meta-analysis of data from 26 RCTs indicated that probiotics significantly improved gut barrier function.

• Significant improvement in intestinal barrier markers
• Reduced zonulin and endotoxin levels
• Enhanced gut barrier integrity across multiple trials

Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis

Goodoory VC et al. • Gastroenterology (2023)

Some combinations of probiotics or strains may be beneficial in IBS.

• Some combinations of probiotics or strains may be beneficial in IBS.
• However, certainty in the evidence for efficacy by GRADE criteria was low to very low across almost all of our analyses.
• Further research warranted to confirm findings

Treating asthma patients with probiotics: a systematic review and meta-analysis

Xie Q et al. • Nutricion hospitalaria (2023)

Conclusion: the use of probiotics in patients with asthma can improve lung inflammation and asthma symptoms, reduce the number of asthma attacks, and have no effect on lung function.

• Meta-analysis was performed using Revman 5.4 software and the combined effect was evaluated by odds ratio (OR) or mean difference (MD) and 95 % confidence interval (CI).
• There was no significant difference in forced expiratory volume in the first second (FEV1) (MD = 0.11, 95 % CI: -0.05, 0.26) and FEV1/FVC (%) (MD = 0.32, 95 % CI: -1.48, 2.12).
• Results: a total of ten references were included, all of which were randomized controlled studies, and a total of 1,101 people were investigated.

Effects of combined treatment of probiotics and metformin in management of type 2 diabetes: A systematic review and meta-analysis

Memon H et al. • Diabetes research and clinical practice (2023)

The addition of probiotics to metformin therapy is associated with improvement in T2DM outcomes.

• The addition of probiotics to metformin therapy is associated with improvement in T2DM outcomes.
• However, high-quality and adequately reported RCTs are needed in the future to confirm our findings.
• Further research warranted to confirm findings

Efficacy and safety of probiotics in IBD: An overview of systematic reviews and updated meta-analysis

Estevinho MM et al. • United European Gastroenterology Journal (2024)

Probiotics show promise in inflammatory bowel disease through multiple mechanisms including butyrate production and immune modulation.

• Benefits for ulcerative colitis remission
• Mechanisms include butyrate and IgA production
• Upregulation of defensins and mucin-2 expression

Early use of probiotics might prevent antibiotic-associated diarrhea in elderly (>65 years): a systematic review and meta-analysis

Zhang L et al. • BMC geriatrics (2022)

We recommend that elderly individuals could be routinely distributed probiotics to prevent AAD development when receiving antibiotic treatment.

• We recommend that elderly individuals could be routinely distributed probiotics to prevent AAD development when receiving antibiotic treatment.
• Published in BMC geriatrics (2022)
• Further research warranted to confirm findings

Preventive Effect of Probiotics on Oral Mucositis Induced by Cancer Treatment: A Systematic Review and Meta-Analysis

Liu YC et al. • International journal of molecular sciences (2022)

We recommend the use of probiotics to prevent and treat oral mucositis during cancer therapy.

• Three trials using Lactobacilli-based probiotics reported that the incidence of oral mucositis in the probiotic group was significantly low (risk ratio [RR] = 0.84, 95% confidence interval [CI] = 0.77−0.93, p = 0.0004).
• Seven trials reported a significantly low incidence of severe oral mucositis in the probiotic group (RR = 0.65, 95% CI = 0.53−0.81, p < 0.0001).
• The requirement of enteral nutrition was significantly low in the probiotic group (odds ratio = 0.34, 95% CI: 0.13−0.92, p < 0.05).

Probiotics for treating acute infectious diarrhoea

Collinson S et al. • The Cochrane database of systematic reviews (2020)

Probiotics probably make little or no difference to the number of people who have diarrhoea lasting 48 hours or longer, and we are uncertain whether probiotics reduce the duration of diarrhoea.

• Effect size was similar in the sensitivity analysis and marked heterogeneity persisted.
• Effect size was similar and marked heterogeneity persisted in pre-specified subgroup analyses of the primary outcomes that included all studies.
• In six trials (433 participants) of Lactobacillus reuteri, there was consistency amongst findings (I² = 0%), but risk of bias was present in all included studies.

Probiotics to prevent infantile colic

Ong TG et al. • The Cochrane database of systematic reviews (2019)

There is no clear evidence that probiotics are more effective than placebo at preventing infantile colic; however, daily crying time appeared to reduce with probiotic use compared to placebo.

• There is no clear evidence that probiotics are more effective than placebo at preventing infantile colic; however, daily crying time appeared to reduce with probiotic use compared to placebo.
• Published in The Cochrane database of systematic reviews (2019)
• Further research warranted to confirm findings

Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children

Goldenberg JZ et al. • The Cochrane database of systematic reviews (2017)

Based on this systematic review and meta-analysis of 31 randomized controlled trials including 8672 patients, moderate certainty evidence suggests that probiotics are effective for preventing CDAD (NNTB = 42 patients, 95% CI 32 to 58).

• A complete case analysis (i.e. participants who completed the study) among trials investigating CDAD (31 trials, 8672 participants) suggests that probiotics reduce the risk of CDAD by 60%.
• The incidence of CDAD was 1.5% (70/4525) in the probiotic group compared to 4.0% (164/4147) in the placebo or no treatment control group (RR 0.40, 95% CI 0.30 to 0.52; GRADE = moderate).
• Twenty-two of 31 trials had missing CDAD data ranging from 2% to 45%.

Probiotics for the prevention of antibiotic-associated diarrhea

Hempel S et al. • JAMA (2012)

Probiotics significantly reduced the risk of antibiotic-associated diarrhea.

• 42% reduction in antibiotic-associated diarrhea
• Multiple strains effective
• Benefits seen across age groups

Probiotics for autism spectrum disorder: An updated systematic review and meta-analysis of effects on symptoms

Soleimanpour S et al. • Journal of psychiatric research (2024)

Our study highlighted the significant improvement in ASD behavioral symptoms through probiotic supplementation.

• This was shown by a pooled standardized mean difference (SMD) of -0.38 (95% CI: 0.58 to -0.18, p < 0.01).
• Moreover, both multi-strain probiotics and single-strain interventions showed an overall significant improvement with a SMD of -0.53 (95%CI: 0.85 to -0.22) and -0.28 (95%CI: 0.54 to -0.02), respectively.
• Our study highlighted the significant improvement in ASD behavioral symptoms through probiotic supplementation.

Probiotics for preventing acute upper respiratory tract infections

Hao Q et al. • Cochrane Database of Systematic Reviews (2015)

Probiotics were better than placebo in reducing the number of participants experiencing acute URTIs.

• Reduced frequency of respiratory infections
• Shorter duration of illness
• Reduced antibiotic prescription rates

Probiotics and anxiety: A systematic review

Reis DJ et al. • Journal of Affective Disorders (2018)

Probiotic supplementation showed a small but significant effect on anxiety symptoms.

• Modest reductions in anxiety measures
• Effects more pronounced in clinical populations
• Strain-specific effects observed

Effectiveness of probiotic supplements in managing pulmonary function and inflammatory status in patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis.

Zhang Q, Zhang N, Zheng Y, Zhou J, Liu L, Dong G • Clin Nutr (2026)

Efficacy and Safety of Lactobacillus reuteri DSM 17938 in Pediatric Functional Abdominal Pain Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Rodríguez-Brown F, Guerra Valencia J, Hernández-Vásquez A • Nutrients (2026)

Efficacy and Safety of Probiotics, Prebiotics and Synbiotics for the Treatment of Functional Constipation in Children: Systematic Review and Network Meta-analysis.

Liang C, Deng X, Wang H, Hu X, Cui L, Huang J • Probiotics Antimicrob Proteins (2026)