L. rhamnosus GG (LGG): The World's Most-Studied Probiotic
Updated April 2026 · 800+ clinical papers · Sources: Cochrane, ESPGHAN, NIH ODS
What It Is
Lactobacillus rhamnosus GG (ATCC 53103) was isolated from the intestine of a healthy human in 1983 by Sherwood Gorbach and Barry Goldin at Tufts University. The "GG" designation comes from their surnames. It was the first commercially sold probiotic and remains the most comprehensively studied single probiotic strain, with over 800 published clinical papers as of 2025.
LGG stands out for three biological characteristics: it adheres strongly to intestinal mucus, it survives passage through gastric acid and bile without enteric coating, and it produces pili (hair-like appendages) that allow it to interact with intestinal epithelial cells and stimulate immune signalling. These properties make it one of the few probiotics demonstrably able to transiently colonise the human gut after oral administration.
Culturelle is the principal consumer brand built around LGG. It is sold in over 35 countries and is recommended by multiple national paediatric guidelines. Valio (Finland) also markets LGG dairy products commercially.
What the Evidence Says
Acute Diarrhoea in Children
Strong EvidenceThe most robustly supported effect in the probiotic literature. A 2019 Cochrane systematic review (Szajewska & Canani) of 17 RCTs found LGG significantly reduces the duration of acute infectious diarrhoea in children by approximately 1.05 days (95% CI: -1.63 to -0.48). ESPGHAN and ESPID recommend LGG for paediatric acute gastroenteritis. The effect is specific to LGG and L. reuteri - not generalisable to all probiotics.
Cite: Szajewska & Canani, J Pediatr Gastroenterol Nutr 2019; Cochrane Database Syst Rev 2020
Antibiotic-Associated Diarrhoea
Strong EvidenceMultiple RCTs and a meta-analysis support LGG for preventing antibiotic-associated diarrhoea (AAD) in adults and children. Doron et al. (Am J Gastroenterol 2011) found LGG reduced AAD risk by 71% in hospitalised patients. Clinical practice recommendation: start LGG on day 1 of antibiotic therapy, separate doses by 2-3 hours, and continue for 2-4 weeks after the course ends. Note: S. boulardii (a yeast) remains the single strongest option for AAD prevention; LGG is the strongest bacterial option.
Cite: Doron et al., Am J Gastroenterol 2011; Goldenberg et al., Cochrane 2015
Atopic Eczema Prevention
Emerging EvidenceMaternal LGG supplementation during the last weeks of pregnancy and postnatal infant supplementation reduced the incidence of eczema (atopic dermatitis) in at-risk infants by approximately 50% in the landmark HYALYN trial (Kalliomaki et al., Lancet 2001). Long-term follow-up showed persistent benefit at age 7. However, subsequent trials have shown mixed results, and a 2022 Cochrane review found the evidence is inconsistent across settings. Most effective in high-atopic-risk families with a history of eczema or asthma.
Cite: Kalliomaki et al., Lancet 2001; Cuello-Garcia et al., Cochrane 2022
IBS
Limited EvidenceUnlike its strong evidence for diarrhoeal disease, LGG alone has limited evidence for IBS. The 2024 network meta-analysis (PMC10490209) did not rank LGG among the top performers for IBS symptom reduction. B. infantis 35624 and L. plantarum 299v have substantially better IBS-specific evidence. Using LGG for IBS is a reasonable and safe approach, but it is not the evidence-preferred choice.
Cite: Ford et al., Am J Gastroenterol 2024; PMC10490209
Dosing
Clinical trials universally use 10 billion CFU per day of LGG. Culturelle's standard formula provides exactly this. The dose should be maintained consistently - LGG does not provide a residual benefit after discontinuation; the effect ends when dosing ends as it is a transient coloniser.
Timing: LGG can be taken with or without food. Unlike some strains, it survives stomach acid without food buffering, though some research suggests slightly better survival when taken with a meal. Refrigeration extends shelf life; the strain is stable at room temperature for limited periods.
Safety
LGG has one of the most extensive safety databases of any probiotic organism. Rare adverse events: case reports of Lactobacillus bacteraemia have been published in immunocompromised patients receiving LGG supplementation (not the majority of cases, and causality is debated in most). The absolute risk for healthy individuals is negligibly low. ESPGHAN, American Academy of Pediatrics, and World Gastroenterology Organisation have all reviewed the safety profile and found LGG appropriate for use in healthy infants, children, and adults.
Products Containing LGG
Affiliate disclosure: links below may be affiliate links.
Culturelle Daily Probiotic (10 billion CFU LGG)
Strong EvidenceThe flagship LGG consumer product. Available in capsule, chewable, and children's formulations. Widely distributed and affordably priced (~$20-28 for 30 days). Good shelf stability.
Culturelle Kids Daily Probiotic (5 billion CFU LGG)
Strong EvidenceChewable tablet for children 1+. Evidence from paediatric trials typically used 10 billion CFU but 5 billion has been used in some paediatric RCTs with effect. Age-appropriate form.
Renew Life Ultimate Flora (multi-strain including LGG)
Emerging EvidenceMulti-strain formulation that includes LGG among multiple Lactobacillus and Bifidobacterium strains. Higher total CFU count.