What are bacteriophages?

Bacteriophages (also known as phages) are the most common living organism on the planet – there are more bacteriophages than all other living organisms on the earth combined, including bacteria. Composed of proteins, bacteriophages are the natural enemies of various strains of harmful bacteria, while being harmless to humans, animals, and plants.

What do bacteriophages do?

Bacteriophages target specific bacteria in the gut, thus helping to balance the functional aspects of your gut population.* Basically, bacteriophages are prebiotics because they provide a supportive environment in which beneficial bacteria can thrive.* And bacteriophages only target specific types of bacteria, and here’s why that is important: there are three general categories of bacteria in your gut, and you want your bacteriophages to be choosy about which ones they target.

  1. The “good” bacteria in your gut help your body absorb nutrients; synthesize enzymes, vitamins, and neurotransmitters; support your immune system; regulate digestion; and much more. Good bacteria are what we take when we supplement with a probiotic.
  2. The “bad” bacteria are types of bacteria that have no place in a healthy gut environment and can cause issues throughout the body when their growth takes over the gut. Bad bacteria can cause a range of symptoms, such as digestive disturbance, mood issues, and disrupted immune function. Not everyone has a bad bacterial component in their gut, but without specific testing of your gut microbiota, it can be difficult to know. If you’re curious about the population of the multitude of species that inhabit your gut, then check out Gutbio™ by Onegevity Health and wonder no more!
  3. The “opportunistic” bacteria in your gut don’t serve any positive function, but they don’t necessarily cause any adverse issues either. They are essentially space-hogging bacteria that affect the balance of the gut by taking up space the good bacteria otherwise need to grow and flourish.

What does the science say?

Several studies have examined the effects of one specific bacteriophage blend – PreforPro®.

Even though you might not have heard of bacteriophages, there has been a fair amount of research going on behind the scenes. One bacteriophage blend called PreforPro boasts 20 studies – from In vitro (test tube) studies to human studies. For example, in test tube studies, PreforPro supports the growth of the following beneficial bacteria normally found in the intestinal tract: Bifidobacterium bifidum. B. breve, B. animalis subsp. lactis, B. longum, Lactobacillus acidophilus, L. paracasei, L. plantarum, L. rhanmmosus, and Bacillus subtilis.*

In human studies, this bacteriophage blend exhibits both safety and efficacy. In one study, 32 healthy participants with mild GI complaints took 15 mg PreforPro or a placebo for 28 days. Then, after a 2-week period of not taking either, they switched to the opposite treatment for another 28 days so the results could be compared.

There were no negative effects on metabolic blood markers or differences between treatments, which means PreforPro can be taken safely. In addition, there were self reported improvements in GI symptoms while the participants were taking PreforPro.* The authors concluded that, “Consumption of therapeutic doses of a mixture of four bacteriophages was both safe and tolerable in a target human population.”1

In another double-blind, placebo-controlled trial, healthy normal to overweight adults took 15 mg of PreforPro for 28 days. Blood and stool tests were performed at the beginning and end of the trial. Benefits of this prebiotic bacteriophage included increases in beneficial bacteria in the stool and increases in healthy short chain fatty acids like butyrate, which is produced by beneficial bacteria.* In addition, less desirable bacterial populations were decreased.* PreforPro also supported a healthy inflammatory response, with decreases in IL-4, which is associated with allergies.*2

In a third double-blind, placebo-controlled trial, 66 healthy adults were randomly assigned to one of three groups for four weeks: (1) Bifidobacterium lactis probiotic, (2) B. lactis probiotic plus PreforPro, or (3) maltodextrin placebo. Stool tests and digestive questionnaires were performed at the beginning and end of the study.

Both the probiotic and the combination probiotic and prebiotic groups experienced an increase in beneficial Lactobacillus species, with a 10-fold increase in the group that took both and a 4-fold increase in the probiotic-only group. In the results of the symptom questionnaire, a higher percentage (24%) of participants in the combination group had a improvement in symptom scores compared to the probiotic group (15%).3

PreforPro – the lead actor in a unique prebiotic formula

Thorne’s Prebiotic + utilizes PreforPro as the bacteriophage component of its formula. PreforPro helps destroy both the “bad” and the “opportunistic” bacteria, thus creating space in the colonic environment and providing food and support for the growth of “good” bacteria.*

This makes PreforPro a double hitter for achieving a healthy microbiome because it reduces the unwanted components of the microbiota, thus enabling the good components to flourish.* And PreforPro goes to work balancing the bacteria in the gut within hours, not days. There’s no amount of yogurt you could ingest that can go toe to toe with PreforPro.

Prebiotic + – with PreforPro along with polyphenol prebiotics from blueberry, pomegranate, and green tea – provides an attractive alternative to fiber-based prebiotics that can often cause gas and bloating.


  1. Gindin M, Febvre H, Rao S, et al. Bacteriophage for gastrointestinal health (PHAGE) Study: Evaluating the safety and tolerability of supplemental bacteriophage consumption. J Am Coll Nutr 2019;38(1):68-75. 
  2. Febvre H, Rao S, Gindin M, et al. PHAGE Study: Effects of supplemental bacteriophage intake on . . . gut microbiota in healthy adults. Nutrients 2019 ;11(3):666. 
  3. Grubb D, Wrigley S, Freedman K, 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):2474.