In the PHAGE-2 clinical trial (#NCT04511221), the addition of bacteriophages to a probiotic containing bifidobacteria improved gut health and gut microbiota in healthy adult volunteers.

Probiotics are widely prescribed by doctors and used by consumers to improve gastrointestinal (GI) function and metabolism. Probiotics are accessible, convenient, and relatively inexpensive means of regulating the gut microbiota, whose vital role in the normal functioning of the human body is no longer in doubt.

Scientists from Colorado State University and George Mason University (USA) decided to test whether bacteriophages could enhance the beneficial effects of the probiotic strain Bifidobacterium animalis subsp . lactis ( B. lactis ) on the digestive tract. They recruited 68 healthy volunteers for a randomized, double-blind, placebo-controlled trial. The primary outcome included subjective assessments of gastrointestinal health, stool consistency, and 16S rRNA analysis of the gut microbiota to assess its composition.

Subjects were randomly divided into three groups: one received the probiotic B. lactis strain (1×109 ^CFU ), the second received B. lactis ( 1×109 ^CFU ) and a commercially available phage cocktail specific for E. coli (1× ¹⁰⁶ PFU), and the third received a placebo. The phage cocktail contained LH01-Myoviridae, LL5-Siphoviridae, T4D-Myoviridae, and LL12-Myoviridae and has previously been shown to positively influence the growth of bifidobacteria. Participants took one capsule of the corresponding preparation per day for 4 weeks. Participants followed their usual diet and provided information about their diet and physical activity to the researchers.

Read also: Bacteriophages as a means of improving the microbiome

As a result, the group receiving B. lactis and the phage cocktail showed a significant reduction in gastrointestinal inflammation (p = 0.01) and colon pain (p = 0.08) compared to the group receiving the probiotic alone. Stool analysis also revealed a significant increase in the population of lactobacilli and short-chain fatty acid-producing bacteria in participants receiving the combination of B. lactis and the phage cocktail compared to those receiving the probiotic alone.

According to the authors, the study proves that the addition of bacteriophages can significantly enhance the positive effects of traditional probiotics on the microecology of the digestive tract.

* Grubb DS, Wrigley SD, Freedman KE, et al. PHAGE-2 Study: Supplemental Bacteriophages Extend Bifidobacterium animalis subsp. lactis BL04 Benefits on Gut Health and Microbiota in Healthy Adults. Nutrients. 2020; 12(8):E2474. https://doi.org/10.3390/nu12082474