Cross-referencing clinical data
EarlySiphoviridae LL5
Siphoviridae LL5.
A bacteriophage strain targeting harmful gut bacteria. Part of the PreforPro phage blend. Hunts and destroys specific harmful bacteria in your gut, shifting the balance toward a healthier microbiome.
EarlyResearch strength15mgDaily amount
Reviewed March 2026
- Category
- General
- Also filed under
- Targets specific harmful gut bacteriaSupports microbiome diversityPart of studied PreforPro blend
What Siphoviridae LL5 is, and what it does.
- Does it work
- The phage concept is brilliant and the science is real. But LL5 has never been studied alone. All evidence comes from the 4-phage PreforPro blend. You're buying the team, not the player.
- How much to take
- 15 mg as part of the full PreforPro blend. No standalone dosing exists because it's never been tested in isolation.
- The first dose
- Zero noticeable effects. The phages are working at a microscopic level immediately, but you won't feel a thing.
- With regular use
- Weeks 3-4: some users report subtle improvements in digestive comfort. The blend studies showed statistically modest but real changes in gut bacteria composition.
- How well tolerated
- About as safe as supplements get. Phages can't infect human cells. Period. They're part of your normal gut ecology already.
- How it feels
- Invisible. The work happens at a bacterial level you can't sense. Any benefits manifest as gradual digestive improvements, not a noticeable sensation.
About 15mg a day is the studied dose.
How much to take a dayLimited data
15mg
The doseThe daily amount the trials actually used. A product at this figure is dosed right where the research is.
Above 15mgMore capsules, not more effect. Rarely in a serving anyway.
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
- Selectively kills harmful gut bacteria
- Supports probiotic colonization
PubMedCochraneClinicalTrials.govNIH ODSSUPP.AILabs test. IngredientMD verifies.PubMedCochraneClinicalTrials.govNIH ODSSUPP.AILabs test. IngredientMD verifies.
Questions people ask about Siphoviridae LL5.
- What makes Siphoviridae different from the other phages in PreforPro?
- Each phage family targets different bacteria. Siphoviridae have long flexible tails and tend to target different bacterial species than Myoviridae phages. Together, they cover more ground.
- Can bacteria become resistant to phages?
- Yes, but phages evolve too. It's an arms race that's been going on for billions of years. Multi-phage cocktails (like PreforPro) make resistance much harder for bacteria to develop.
- Are phages better than probiotics?
- Different tools, different jobs. Phages remove bad bacteria. Probiotics add good bacteria. They actually work better together than either alone.
- How do I know the phages are alive in my supplement?
- Look for products that list phage viability or plaque-forming units (PFU). PreforPro is tested for viability. Dead phages don't work.
- Will this mess up my microbiome?
- The opposite. Phages are incredibly targeted. They only kill their specific bacterial host. Everything else in your microbiome is completely untouched.
- Is phage therapy the same as phage supplements?
- Related but different. Phage therapy uses clinical-grade phages to treat active infections. Phage supplements use food-grade phages for general gut health maintenance. Much lower intensity.
Nothing to show here, and the reason why.
A pairing appears on this page only when a trial gave both ingredients together and measured the result. Siphoviridae LL5 has none that clears that bar.
No pairing for Siphoviridae LL5 has cleared review yet.
Stitching two separate single-ingredient studies into a pairing is the one thing this engine will not do. When a study of the combination itself holds up at source, it lands here with its citation.
No invented synergy. Where actives were studied on their own rather than together, the record shows each on its own evidence, never a combined effect no trial measured.
Research strength. Research strength says how much work stands behind the combination. It is never a product score.
Independent record. Every finding is cited to a named trial, dated, and never written by the brand.
20 pairings are live across the library today. Checked 20 July 2026.
Plays well withEstablished knowledge, not a trial
No study gave these as a pair, so they are not in the card above. But the reason they belong together is settled biochemistry, not a guess, so it is worth knowing.
Siphoviridae LL5 + Probioticsphage clears a competing coliform niche
This lytic phage targets defined Escherichia coli strains and leaves lactic acid bacteria untouched, so lysing the target population frees nutrients and attachment sites. Co dosed probiotic strains are the ones able to take up that space.
Siphoviridae LL5 + Lactobacillus plantarumselective lysis of a competitor, not the probiotic
Narrow phage host range means the delivered Lactobacillus carries none of the receptors the phage needs and passes through intact. Competition in the shared niche narrows while the strain is preserved.
Siphoviridae LL5 + Lactobacillus Rhamnosushost range excludes the co dosed strain
Coliform phages cannot adsorb to Lactobacillus rhamnosus, so the two are stable in one formula. The phage acts only on the competing coliform population in the same environment.
Siphoviridae LL5 + InulinPrebiotic fibre expands the bacterial populations that a lytic phage needs as hosts, and shifts community composition in the same compartment.
A lytic bacteriophage can only replicate where its host species is present and metabolically active, so anything that changes host density changes phage dynamics. Inulin selectively feeds bifidobacteria and some lactobacilli, which is a different part of the community than most phage targets. The direction of any net effect depends on which species the phage recognises. It supports normal microbial balance in the colon; no combination has been measured for this particular phage.
Siphoviridae LL5 + FOS fructooligosaccharidesShort-chain fructans feed saccharolytic commensals, altering the host landscape a phage preparation encounters.
Phage preparations are usually positioned as clearing space that beneficial organisms then occupy, and a fermentable substrate is what lets those organisms take the space. The two act at different points of the same sequence rather than on the same target. Whether that sequence plays out as described has not been measured for this phage. The pairing is formulation logic supported by general microbial ecology.
Siphoviridae LL5 + GOS galactooligosaccharidesGalactooligosaccharides selectively support bifidobacteria, the group most phage products are positioned to leave untouched.
Phage host ranges are narrow by nature, usually confined to particular strains within a species, which is the basis of the selectivity claim made for phage preparations generally. Feeding a non-target group at the same time is a coherent pairing. Nothing here has been demonstrated for Siphoviridae LL5 specifically. The combination supports normal colonic microbial composition.
Siphoviridae LL5 + Bifidobacterium longumPhage preparations are formulated alongside probiotic strains on the reasoning that reducing competing organisms eases colonisation.
Phage preparations are commonly formulated alongside probiotic strains on the reasoning that reducing competing organisms eases colonisation. Bifidobacteria are not typical Siphoviridae hosts in the products these preparations appear in, so co-administration is plausible on paper. The colonisation effect itself has not been shown for this phage with this strain. Read it as the formulation's own rationale rather than a measured result.
Siphoviridae LL5 + Lactobacillus acidophilusCommon companion strain in phage-containing probiotic formulas.
Formulas that carry a phage cocktail typically pair it with several lactobacilli, on the reasoning that the phage narrows competition while the strains fill the space. Any lactobacillus is itself a potential phage host depending on the phage's receptor specificity, which is worth knowing rather than assuming away. Host range data for this particular phage against this strain are what would settle it. Until then the pairing is a formulation convention.
Siphoviridae LL5 + Saccharomyces boulardiiA yeast has no bacteriophage receptors at all, so it cannot be a target of any phage preparation.
Bacteriophages attach to bacterial surface structures such as teichoic acids, lipopolysaccharide or pili, none of which exist on a fungal cell wall. Saccharomyces boulardii is therefore structurally immune to phage predation, which makes it a straightforward companion in any phage-containing formula. This is settled virology rather than a tested pairing. It supports normal gut microbial balance through an entirely separate route.
Siphoviridae LL5 + ButyrateButyrate is the metabolic output of the commensal populations that phage preparations are meant to favour, so it sits downstream of the same intended effect.
Where a phage narrows a competing population, the expected consequence is more substrate reaching butyrate producers. Supplying butyrate directly delivers the endpoint without depending on that chain of events happening. The two approach the same outcome from opposite ends. Neither has been measured alongside the other for this phage.
Siphoviridae LL5 + Betaine HClGastric acid inactivates most bacteriophage particles, so anything that lowers gastric pH reduces the dose that survives to the colon.
Phage capsid stability falls sharply below about pH 3, and survival through the stomach is the central formulation problem for any oral phage product. Deliberately acidifying the stomach with betaine hydrochloride works against that. This is established phage physical chemistry, not a claim about a particular product. Enteric coating or buffering exists precisely to address it.
Siphoviridae LL5 + Sodium bicarbonateRaising gastric pH improves the survival of acid-labile phage particles through the stomach.
Buffering agents are used in phage delivery research for exactly this reason: acid inactivation is the main loss route between swallowing and the colon. Sodium bicarbonate raises gastric pH transiently, which would be expected to preserve more infective particles. The principle is established; the magnitude for any particular preparation and dose has not been quantified here. Enteric encapsulation achieves the same goal by a different route.
Siphoviridae LL5 + Activated charcoalActivated charcoal adsorbs particles and macromolecules non-selectively across a wide size range.
Charcoal's surface binds a broad range of organic material in the gut lumen, and a protein-coated virion is a plausible binding target. Taking the two together would be expected to reduce the number of infective particles reaching their hosts. The adsorption principle is well established even though this specific pair has not been measured. Separating the two by several hours is the usual handling of any charcoal interaction.
Siphoviridae LL5 + Bentonite clayClay minerals adsorb viruses efficiently, a property used in water treatment.
Montmorillonite clays bind virus particles through electrostatic and surface interactions well enough to be used for virus removal in water processing. That same property would apply to an ingested phage preparation sharing the lumen with clay. The mechanism is established colloid chemistry rather than a gut study. Spacing the two apart in the day is the practical implication.
Siphoviridae LL5 + LactoferrinLactoferrin binds bacterial surface lipopolysaccharide, which is also where many phages attach.
Lactoferrin's antibacterial action includes direct binding to lipopolysaccharide on gram-negative surfaces, and lipopolysaccharide is a common phage receptor. Occupying the same surface structures could interfere with adsorption, or could sensitise the cell by disrupting the envelope. Which of those dominates has not been established for this pair. It is a mechanistic flag rather than a directional recommendation.
Siphoviridae LL5 + Resistant starchResistant starch shifts fermentation toward butyrate producers, changing the community a phage preparation is introduced into.
Different fibres select for different genera, and the resident community determines both which hosts are available and how quickly a phage population rises or falls. Resistant starch favours a distinct set of colonic organisms from inulin-type fructans. The interaction is community ecology, well described in general and unmeasured for this phage. It supports normal fermentation patterns in the colon.
Who should be cautious
Talk to a doctor before taking Siphoviridae LL5 if any of these apply to you: Individual strain not studied in isolation, Bacteriophage therapy is still emerging. These are flags to check first, not effects Siphoviridae LL5 is known to cause.
Not medical advice. Show the label to your pharmacist.Getting Siphoviridae LL5 from food.
The whole-food sources on file. A supplement closes the gap, it does not replace dinner.
Fermented vegetablesRaw dairy productsEnvironmental water
A gram-for-gram figure (how much of each you would eat to match a dose) will appear here once it is sourced and reviewed. This page will not print a number it cannot cite.
The forms it comes in.
Lyophilised phage preparation with a cryoprotectantThe purified lysate is frozen with a sugar or polyol cryoprotectant such as trehalose or sucrose and dried under vacuum, which preserves capsid structure without heat.Fits Dry blends and capsules where shelf stability at ambient temperature is the constraint and the particle count is declared as plaque forming units.Trade-off Every freeze-drying and rehydration cycle costs some infective titre, so the declared count depends on the overage built in at manufacture and on how the product is stored.
Delayed-release capsule with an acid-resistant coatingThe dried preparation is filled into a capsule coated with a polymer that stays intact at gastric pH and dissolves at the higher pH of the small intestine.Fits Products where surviving the stomach is the design priority, since phage capsids lose infectivity in acid.Trade-off The coating adds mass and cost, and release depends on gastric transit and on how quickly intestinal pH rises, which varies between people and with meals.
Buffered aqueous suspensionParticles are held in a buffered saline or glycerol-containing solution near neutral pH, which is the native state for a phage and needs no drying step.Fits Research use and any application where titre needs to be verified by plaque assay immediately before use.Trade-off Titre falls with time and temperature in solution, so the format usually needs refrigeration and carries a shorter shelf life than a dried powder.
What the strongest studies found
The essence, in one line each.
- In adults, a supplemental bacteriophage preparation taken alongside Bifidobacterium animalis subsp. lactis BL04 was compared with the probiotic alone for effects on gut bacteria and digestive comfort.Randomised trial. Grubb et al., 2020 (Nutrients). PMID 32824480 ↗
These are the studies our verdict leans on, chosen from the 9 we read for Siphoviridae LL5. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.
