Abstract
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 2 weeks. Compared to the two-week run-in period, iVS-1 abundance was higher both at the end of the treatment period (p = 0.0005) and after the 2-week post-treatment period (p = 0.045). The iVS-1 group reported 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 suggest that B. adolescentis iVS-1 may be an effective treatment for lactose intolerance.
Introduction
Lactose intolerance is a multifactorial condition in which individuals experience gastrointestinal symptoms following consumption of lactose-containing products, including milk and ice cream. Lactose intolerance occurs in individuals who are unable to produce sufficient amounts of β-galactosidase in the small intestine, such that lactose reaches the colon and is metabolized by microbes that produce acids and gas. Other factors may also contribute to this condition, including anxiety disorders, psychosocial stress, and functional GI disorders. Although some lactose maldigesters can safely consume small amounts of lactose, the condition is commonly managed by eliminating lactose-containing foods from the diet. In contrast, yogurt, kefir, and other cultured milk products, despite containing nearly as much lactose as milk, are generally well tolerated, due to expression and in situ release of β-galactosidase by the starter culture bacteria.
Likewise, many studies have assessed the ability of probiotic bacteria, including specific strains of lactobacilli and bifidobacteria, to consume lactose and reduce symptoms associated with lactose maldigestion. In one study, 2-week supplementation with Bifidobacterium longum capsules and Bifidobacterium animalis subsp. lactis-enriched yogurt was conducted in lactose-intolerant subjects. Both strains were detected in stool samples during supplementation. It was also noted that symptoms improved post-supplementation. There is a mixed record for improvement of symptoms due to Bifidobacterium supplementation in other acute and chronic studies. Some studies tested only Bifidobacterium strains, while the other studies included an additional probiotic with Bifidobacterium.
In this study, we conducted a randomized clinical pilot trial to examine whether lactose intolerance symptoms could be improved by consumption of Bifidobacterium adolescentis iVS-1. This strain had been isolated from a stool sample of a human after enrichment through consumption of galactooligosaccharides (GOS) and was identified as B. adolescentis by 16S rRNA gene sequencing. The strain also grew rapidly on GOS in vitro, reaching high cell density. Because GOS, like lactose, is hydrolyzed by β-galactosidase, we hypothesized that this autochthonous strain could also digest and consume lactose well in human subjects. In addition, subsequent analysis of the iVS-1 genome revealed that nine β-galactosidase genes were present. Accordingly, the primary objective of this study was to assess the suitability of B. adolescentis iVS-1 to improve symptoms associated with lactose intolerance via both in vitro experiments and a clinical trial of lactose maldigesters given iVS-1 as a dietary supplement.
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Ramakrishnan, M., Cross, T. W. L., Organski, A. C., Saiprasad, S. M., Simpson, A. M. R., Tancredi, D. J., … Savaiano, D. A. (2025). Two-week supplementation of Bifidobacterium adolescentis iVS-1 reduces symptoms associated with lactose intolerance in lactose maldigesters. Gut Microbes Reports, 2(1). https://doi.org/10.1080/29933935.2025.2508199
