Which probiotics (probiotic bacteria) are effective in reducing diarrhea?

Which Probiotics Reduce Diarrhea: Evidence-Based Recommendations

Context-Dependent Recommendations

The effectiveness of probiotics for diarrhea depends critically on the clinical context, patient location, and type of diarrhea, with different strains showing benefit in specific populations but not universally.

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For Acute Infectious Gastroenteritis in Children

In North America (United States/Canada)

Do NOT use probiotics for acute infectious gastroenteritis in children in the United States or Canada. 1

• Two large, high-quality multicenter RCTs (943 and 827 children respectively) conducted in North America showed no benefit for L. rhamnosus ATCC 53103 or the combination of L. rhamnosus R0011 + L. helveticus R0052 1
• These studies found no difference in moderate-to-severe gastroenteritis, stool frequency, hospitalization rates, or Vesikari scale scores 1
• The AGA guidelines specifically recommend against probiotic use in this population based on moderate-quality evidence 1

Outside North America (Europe, Asia, Developing Countries)

Consider using Saccharomyces boulardii or Lactobacillus rhamnosus GG (LGG) for acute gastroenteritis in children outside North America. 1

Most effective strains based on evidence:

1. Saccharomyces boulardii (strongest evidence)

   • Reduces diarrhea duration by approximately 28.9 hours (95% CI: 16.78-41.03 hours) 1
   • Reduces risk of diarrhea lasting >4 days (RR 0.45; 95% CI: 0.32-0.64) 1
   • May be the single most effective probiotic for acute diarrhea 2
   • Evidence quality: Very Low to Low 1

2. Lactobacillus rhamnosus GG (LGG/ATCC 53103)

   • Reduces diarrhea duration by approximately 23.13 hours (95% CI: 12.33-33.94 hours) 1
   • Reduces risk of diarrhea lasting >4 days (RR 0.38; 95% CI: 0.27-0.54) 1
   • Evidence quality: Low 1

3. Lactobacillus reuteri (DSM 17938)

   • Reduces diarrhea duration by approximately 24.36 hours (95% CI: 33.55-13.17 hours) 1
   • Recommended by ESPGHAN for adjunct treatment 1
   • Evidence quality: Low 1

4. Combination: L. acidophilus + B. bifidum

   • Reduces diarrhea duration by approximately 28.44 hours (95% CI: 45.72-11.15 hours) 1
   • Evidence quality: Low 1

Critical caveat: Most positive studies were conducted in India, Italy, Poland, Turkey, and Pakistan with concerns about risk of bias 1. Geographic differences in host genetics, diet, sanitation, and endemic pathogens limit generalizability 1.

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For Antibiotic-Associated Diarrhea (Prevention)

Use Lactobacillus rhamnosus GG or Saccharomyces boulardii to prevent antibiotic-associated diarrhea in both children and adults. 1, 3, 4

• Saccharomyces boulardii and LGG have the strongest evidence for prevention 1, 4
• Probiotics reduce the risk of antibiotic-associated diarrhea by approximately 50% 5
• Dose matters: Higher doses (≥10^10 CFU/day) show better efficacy 3
• Evidence quality: Moderate to High 1, 3

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For Clostridioides difficile Infection (CDI)

Treatment of Active CDI (Adjunct to Antibiotics)

Consider Saccharomyces boulardii (1g, 3×10^10 CFU/day) as adjunct to standard antibiotic therapy for CDI. 1

• May increase cessation of diarrhea (RR 1.33; 95% CI: 1.02-1.74) 1
• May decrease recurrence of diarrhea (RR 0.59; 95% CI: 0.35-0.98) 1
• Evidence quality: Low 1
• Only 5 small trials (223 total patients) with high risk of bias 1

Prevention of CDI in Patients Taking Antibiotics

Probiotics reduce the risk of developing CDI by 64% when given with antibiotics. 1

• Evidence supports use for prevention, though optimal strains and doses need further study 1
• Evidence quality: Moderate 1

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For Preterm/Low Birth Weight Infants (NEC Prevention)

Use combination probiotics containing Lactobacillus spp. + Bifidobacterium spp., or single-strain B. animalis subsp. lactis, L. reuteri, or L. rhamnosus for NEC prevention in preterm infants <37 weeks gestational age. 1

• Evidence quality: Moderate to High 1
• This is one of the strongest indications for probiotic use 1

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For Irritable Bowel Syndrome (IBS)

Evidence is insufficient to recommend specific probiotics for IBS, though treatment duration should not exceed 12 weeks if attempted. 6

• Discontinue if no improvement within 12 weeks 6
• Multiple small trials with heterogeneous designs and high risk of bias 1
• Evidence quality: Very Low 1

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Dosing and Duration Considerations

• Dose-dependent effect: Higher doses (≥10^10 CFU/day) generally more effective 3
• Duration for acute diarrhea: Typically 5 days 1
• Duration for IBS: Maximum 12 weeks 6
• Strain-specific effects: Benefits are NOT generalizable across different probiotic strains 3, 4

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Safety Considerations

Probiotics are generally safe but exercise caution in:

• Immunocompromised patients 1, 5
• Premature neonates (except for specific NEC prevention protocols) 1
• Patients with central venous catheters 1, 5
• Critically ill patients 1
• Cardiac valvular disease 1
• Short-gut syndrome 1

Rare cases of invasive infections have been reported in these high-risk populations 5.

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Key Clinical Pitfalls to Avoid

1. Geographic context matters: Do not extrapolate non-North American pediatric gastroenteritis data to US/Canadian populations 1
2. Strain specificity is critical: Different strains have different effects; cannot substitute one for another 3, 4
3. Not all "Lactobacillus" are equal: Recent taxonomic reclassification means L. rhamnosus is now Lacticaseibacillus rhamnosus and L. reuteri is Limosilactobacillus reuteri 1
4. Heat-killed preparations are NOT probiotics: Some studies used non-viable organisms that don't meet probiotic definitions 1
5. Publication bias exists: Multiple registered trials never published results, suggesting negative findings 1