Probiotic i3.1 Safely and Effectively Decreases Patient-Reported Symptoms of Lactose Intolerance

Investigators assessed the safety and efficacy of probiotic i3.1 for symptom improvement in patients with lactose intolerance.

The i3.1 probiotic was found to reduce symptoms of lactose intolerance safely and effectively but did not alter lactose hydrogen breath test (LHBT) results, according to an 8-week trial published in the Journal of Clinical Gastroenterology.

Patients (N=48) with lactose intolerance with LHBT ³20 parts per million and Symptoms Questionnaire for Lactose Malabsorption Screening score ³6 were recruited at the Hospital Juárez de México for this randomized, placebo-controlled, single-blind clinical trial. Patients were randomly assigned to receive 8 weeks of i3.1 (n=33) or placebo (n=15). Changes in symptoms from baseline were evaluated. The LHBT was assessed at 10 minutes before and 60, 120, and 180 minutes after ingestion of 25 g lactose.

The intervention and control cohorts were aged mean 39.1±13.0 and 44.4±18.3 years, 61% and 67% were women, mean body mass index was 25.9±4.0 and 28.2±5.2 kg/m2, and total symptom scores were 10.0±2.4 and 8.7±1.5 points, respectively.

At 8 weeks, the change from baseline in symptom scores were -5.11±2.97 points among the probiotic and -1.00±1.84 points among the placebo recipients (P <.001).

For symptom subscores, the probiotic recipients had decreased scores for flatulence (P =.004) and abdominal pain (P =.045). The area under the curve for LHBT scores was significantly reduced among the probiotic recipients (P =.019) but there was no group difference compared with placebo (P =.621).

Most patients did not report any adverse events (87.9% vs 80.0%); 1 event was reported by 9.1% and 13.3% and 2 events by 3.0% and 6.7% in the intervention and placebo cohorts, respectively. Adverse events included abdominal distension (n=7), headache (n=2), abdominal pain (n=2), and nausea (n=1).

This study was limited by its reliance on self-reported symptom outcomes.

These data indicate that the probiotic i3.1 may be effective and safe for reducing patient-reported symptoms of lactose intolerance, which may indicate a more pronounced effect on visceral sensitivity than lactose degradation itself.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Cano-Contreras AD, Alfaro IJM, López VMM, et al. Efficacy of i3.1 probiotic on improvement of lactose intolerance symptoms: a randomized, placebo-controlled clinical trial. J Clin Gastroenterol. 2022;56(2):141-147. doi:10.1097/MCG.0000000000001456