Probiotic supplements containing high β-galactosidase-producing bacteria may aid in the management of lactose intolerance. We previously isolated a strain of Bifidobacterium adolescentis, iVS-1, from the fecal sample of a human donor after consumption of galactooligosaccharides (GOS), a prebiotic derived from lactose. Therefore, it was hypothesized that iVS-1 might reduce symptoms associated with lactose maldigestion. Compared to other probiotic strains, iVS-1 had high β-galactosidase activity and reduced gas formation by fecal communities during in vitro fermentations of lactose or milk. A randomized placebo-controlled clinical trial was then conducted with 21 lactose maldigesters, randomized to receive either B. adolescentis iVS-1 (n = 11) or placebo (n = 10) daily for two weeks. Compared to the two-week run-in period, iVS-1 abundance was higher at the end of the treatment period (p = 0.0005) and after the two week post-treatment period (p = 0.045). The iVS-1 group experienced less overall daily symptoms during the treatment period when compared to placebo (p = 0.032) and had significant improvement for fecal urgency (p = 0.033) and diarrhea (p = 0.006). The metabolism of lactose, reduction of gas, and improvement of multiple gastrointestinal symptoms suggests B. adolescentis iVS-1 may be an effective treatment for lactose intolerance.

MJVH, CMC, ZTL, and TAA are affiliated with, and JW and RH are advisors to, Synbiotic Health, which provided funding for this study. The other authors declare no conflicting interest.

NCT05668468

Synbiotic Health provided funding for this study.

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The study was registered with ClinicalTrials.gov under the identifier NCT05668468 and approved by the Purdue Institutional Review Board (IRB-2021-1099). The study adhered to the principles of the Helsinki Declaration of 1975, as revised in 2008, and followed the International Conference on Harmonization Good Clinical Practice guidelines.

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16S rRNA gene data has been deposited in NCBI’s Sequence Read Archive under BioProject ID PRJNA1162892. R code used to generate figures and calculate statistics, and related files are available at https://github.com/auchtung/Ramakrishnan2024. [To be posted upon acceptance of manuscript]