Legacy AI grade · Sources dated 2026-07-25. Not expert reviewed. Coverage is limited to the listed sources. About the new summary workflow
Lactobacillus rhamnosus GG (LGG) for Travelers Diarrhea
Verdict: Published with Warning
Across 6 PubMed studies, the evidence for Lactobacillus rhamnosus GG (LGG) in Travelers Diarrhea grades Tier C — weak evidence. Effective, but with safety or population caveats.
C 🟠 C Weak Evidence Published with Warning
Why this grade7-layer evidence engine
LGG for travelers' diarrhea lacks strain-specific meta-analytic support. The three cited meta-analyses pool multiple probiotic strains and cannot attribute benefit to LGG alone.
Direct LGG RCTs (PMID 2184847, 9815476) are small and dated. PMID 17029137 tested nonviable L. acidophilus, a different strain.
Tier C reflects non-attributable multi-strain evidence. Do not extrapolate genus-level probiotic meta-analyses to LGG specifically.
⚖️
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.46
D
C
B
A
S
← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
C · Published with Warning
Confidence
77%
Broadly consistent
Evidence level
E2
Multiple high-quality MAs (≥2 independent, consistent)
▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.464
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (6)L2 · primary research & systematic reviews
Prophylactic efficacy of probiotics on travelers' diarrhea: an adaptive meta-analysis of randomized controlled trials
Finding: Probiotics as a class significantly reduced TD (pooled RR 0.85, 95% CI 0.79-0.91), but the two dedicated Lactobacillus rhamnosus GG trials were each individually non-significant (Oksanen 1990 RR 0.88, 95% CI 0.75-1.04; Hilton 1997 RR 0.52, 95% CI 0.18-1.52).
View on PubMed Are probiotics and prebiotics effective in the prevention of travellers' diarrhea: A systematic review and meta-analysis
Finding: Only Saccharomyces boulardii CNCM I-745 reached significance (RR 0.79, 95% CI 0.72-0.87, p<0.001), whereas Lactobacillus rhamnosus GG showed only a non-significant trend (p=0.08).
View on PubMed Meta-analysis of probiotics for the prevention of traveler's diarrhea
Finding: Pooled across all probiotics, the class significantly prevented TD (RR 0.85, 95% CI 0.79-0.91, p<0.001); this older analysis pooled strains together and did not establish LGG-specific efficacy on its own.
View on PubMed Prevention of travellers' diarrhoea by Lactobacillus GG
Finding: Diarrhoea occurred in 41.0% of the LGG group vs 46.5% of placebo (overall protection 11.8%, RR ~0.88, 95% CI 0.75-1.04, non-significant overall), reaching significance at only one of two resort destinations.
View on PubMed Efficacy of Lactobacillus GG as a Diarrheal Preventive in Travelers
Finding: TD occurred in 5/126 (LGG) vs 9/119 (placebo) travelers (RR 0.52, 95% CI 0.18-1.52); the point estimate favored LGG but the trial was underpowered and the result was not statistically significant.
View on PubMed Absence of efficacy of nonviable Lactobacillus acidophilus for the prevention of traveler's diarrhea: a randomized, double-blind, controlled study
Finding: Incidence did not differ (61.4 vs 43.4 cases per 100 person-months, p=0.14), showing no benefit; included as a directly relevant negative comparator, though it tested nonviable L. acidophilus, NOT Lactobacillus rhamnosus GG.
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
GRN No. 231 — Notified Substance: Lactobacillus casei subsp. rhamnosus strain GG. Intended Use: Ingredient in term infant formula, at levels not to exceed 10^8 colony forming units per gram of powdered formula. Notifier: Mead Johnson & Company. Agency Response: FDA has no questions (closure date: May 29, 2008). source↗
L4b EU EFSA
Cautious
The bacterial species L. rhamnosus (now Lacticaseibacillus rhamnosus) is considered by EFSA to be suitable for the qualified presumption of safety (QPS) approach to safety assessment. However, the EFSA Panel on Dietetic Products, Nutrition and Allergies concluded that a cause and effect relationship has not been established between the consumption of Lactobacillus rhamnosus GG (ATCC 53103, LGG)… source↗
L4c UK NHS
Neutral
Probiotics are generally classed as food rather than medicine, which means they don't go through the rigorous testing medicines do. ... For most people, probiotics appear to be safe. If you want to try them, and you have a healthy immune system, they shouldn't cause any unpleasant side effects. ... If you have an existing health condition or a weakened immune system, you should talk to a doctor… source↗
L4d TW TFDA / 衛福部
Supportive
Lactobacillus rhamnosus is listed in the 'Food Ingredients Available for Use' (可供食品使用原料) comprehensive list as a lactic acid bacterium (乳酸菌), in the form of bacterial cells (菌體), and can be used as a food ingredient or for food processing purposes. source↗
L4e WHO
Supportive
Administration of Lacticaseibacillus rhamnosus GG (LGG) to children with gastroenteritis is recommended by universal guidelines. The World Gastroenterology Organisation's Global Guidelines for Probiotics and Prebiotics (2023 update) lists LGG as having documented, positive results in multiple gut-related health areas. The FAO/WHO Joint Working Group (London, Ontario, 2002) 'Guidelines for the E… source↗
L5a NIH Office of Dietary Supplements
Supportive
Lactobacillus rhamnosus GG is an example where Lactobacillus is the genus, rhamnosus is the species, and GG is the strain. Treatment with LGG compared with placebo or no additional treatment reduced the risk of antibiotic-associated diarrhea in patients treated with antibiotics from 22.4% to 12.3% (relative risk: 0.49). However, when children and adults were evaluated separately, the difference… source↗
L5d Harvard Health
Cautious
there is some evidence that probiotics may help prevent or treat several different conditions: inflammatory bowel diseases, travelers' diarrhea, antibiotic-related diarrhea (including a severe form called C. difficile colitis), irritable bowel syndrome, and some allergies (particularly eczema). source↗
L5e Specialty Society (condition-mapped)
Cautious
Probiotics (e.g., Lactobacillus GG, Saccharomyces boulardii) have been studied in small numbers of people as TD prevention, but results are inconclusive, partly because standardized preparations of these bacteria are not reliably available. Studies of probiotics to prevent TD are ongoing, but data are insufficient to recommend their use. source↗