Efficacy of i3.1 Probiotic on Improvement of Lactose Intolerance Symptoms: A Randomized, Placebo-controlled Clinical Trial : Journal of Clinical Gastroenterology

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Alimentary Tract: Original Articles

Efficacy of i3.1 Probiotic on Improvement of Lactose Intolerance Symptoms

A Randomized, Placebo-controlled Clinical Trial

Cano-Contreras, Ana D. MD, PhD*; Minero Alfaro, Isidro J. MD*; Medina López, Víctor M. MD, MSc*; Amieva Balmori, Mercedes MD; Remes Troche, José M. MD, PhD; Espadaler Mazo, Jordi PhD; Perez Lopez, Nuria MD, PhD*

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Journal of Clinical Gastroenterology 56(2):p 141-147, February 2022. | DOI: 10.1097/MCG.0000000000001456



The aim of this study was to assess the efficacy of probiotic i3.1 in improving lactose intolerance symptoms compared with placebo after 8 weeks of treatment.


Probiotics are promising strategies to prevent and improve lactose intolerance symptoms, but previous studies have provided conflicting results.

Materials and Methods: 

This randomized, prospective, placebo-controlled study was conducted at the Hospital Juárez de México. We recruited adult patients with lactose intolerance confirmed by a lactose hydrogen breath test (LHBT) ≥20 parts per million (ppm) and a lactose intolerance symptom score ≥6 both upon lactose challenge. We compared the change from baseline in the scores of a validated symptom questionnaire and the LHBT after 8 weeks of probiotic or placebo treatment.


We included 48 patients: 33 receiving the probiotic and 15 receiving placebo (2:1 randomization). Demographic characteristics were homogeneous between groups. The reduction in total symptom score after a lactose challenge was significantly higher in the probiotic group versus the placebo group (−5.11 vs. −1.00; P<0.001). All the subscores significantly decreased from baseline in the probiotic group, except for vomiting, with significant differences between the probiotic and placebo groups for abdominal pain (P=0.045) and flatulence (P=0.004). The area under the curve of the LHBT was significantly reduced from baseline in the probiotic group (P=0.019), but differences between groups were not significant (P=0.621). Adverse events were mild without differences between groups, and no serious adverse event was registered.


The i3.1 probiotic was safe and efficacious in reducing lactose intolerance symptoms in patients with lactose intolerance, but did not change the LHBT.

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