Lactoperoxidase
EVIDENCE: MODERATEAlso sold as: LPO, lactoperoxidase system, thiocyanate peroxidase, SCN- oxidase
Lactoperoxidase is an enzyme in saliva that uses peroxide and thiocyanate to form the antimicrobial compound hypothiocyanite. Human research includes combined enzyme toothpastes and lactoferrin-plus-lactoperoxidase tablets. These studies do not establish every supplement’s effects.
Compiled by iSupplementReviews editorial team ·Updated 2026-10-06 · 5 sources
- Type
- Enzyme — salivary antimicrobial system
- Studied dose
- ~1.8–7.8 mg/day in oral tablets (LF+LPO combination trials); activity-unit dosing in toothpastes
- Best form
- Formulated with its reaction partners (glucose oxidase to make hydrogen peroxide, thiocyanate donors) — LPO alone has no substrate to work on
- Our rating
- MODERATE — Several human trials — limits in size, duration, or independence
What is lactoperoxidase?
Lactoperoxidase is an enzyme found in saliva, tears, and milk. It converts peroxide and thiocyanate into hypothiocyanite, which acts against certain bacteria. The enzyme needs its reaction partners; its name alone does not establish antimicrobial activity in a product.
Other names and forms it’s sold as
- LPO / lactoperoxidase system: the enzyme plus its substrates (hydrogen peroxide, thiocyanate)
- Enzyme toothpaste systems: LPO + glucose oxidase + amyloglucosidase + lysozyme combos (Zendium-style products are the classic example)
- LF+LPO tablets: lactoferrin-bundled oral tablets, the form tested in the two Japanese trials
What is it claimed to do?
Rebuild the mouth’s own antibacterial chemistry, suppress pathogen overgrowth, support gum health. A mechanism claim rather than a kill claim. That framing is to the science: the system works by tilting the community, not sterilizing it.
What does the research show?
| Claim | Evidence | Dose studied | Verdict |
|---|---|---|---|
| Supports gingival health | 150-subject trial: LF+LPO tablets (60mg+7.8mg/day) significantly improved gum scores vs placebo at 12 weeks | 7.8mg LPO/day | Supported — modest, healthy-adult population |
| Helps established periodontitis | 72-patient trial: bovine lactoferrin rose in gum fluid but clinical/bacterial markers didn’t separate from control | 1.8mg ×3/day | Weak — biomarker moved, disease markers didn’t |
| Shifts oral microbiome toward health | Enzyme toothpaste trial: health-associated species up, pathogen-associated species down | toothpaste LPO system | Supported (topical format) |
| Antimicrobial mechanism | Fully characterized — hypothiocyanite generation is textbook salivary biochemistry | — | Supported (mechanism) |
| Benefits as a standalone swallowable | No trials of LPO alone in supplement form | — | Unproven |
The two-trial reality check
Human LPO-tablet studies have produced mixed results. Nakano 2019 (n=150): gum inflammation scores significantly better than placebo at 12 weeks, a real positive for healthy adults. Morinaga 2011 (n=72, periodontitis patients): the marker the product raises (bovine lactoferrin in gum fluid) did rise, proof of concept that an oral tablet reaches the mouth, but plaque bacteria and clinical gum parameters didn’t move versus control. Read together: plausible benefit for routine gingival maintenance; not a periodontitis treatment.
What dose was studied?
| Goal | Dose | Form/route | Duration |
|---|---|---|---|
| Gingival health (positive trial) | LPO 7.8mg/day + LF 60mg/day | Oral tablets | 12 weeks |
| Periodontitis (trial finding no benefit) | LPO 1.8mg + LF 100mg, 3×/day | Oral tablets | 12 weeks |
| Microbiome shift | LPO system toothpaste | Brushing 2×/day | 4–26 weeks |
Side effects
Well tolerated in all trials; it’s a protein your body already makes. Digestive upset is theoretically possible at protein doses; no signal in trials.
Drug interactions
None documented. Antibiotics don’t degrade it the way they do live probiotics; nothing else interacts at these doses.
Who should not take it?
Strict dairy-allergic users should note it’s a bovine-milk-derived protein (an allergen flag many labels omit). Otherwise no established exclusions; it’s already in your saliva.
What the authorities say
No regulator has assessed LPO for oral health claims. It sits in the toothpaste/supplement space where the trials live but the claims remain vendor assertions.
What to know about lactoperoxidase
Combined toothpastes and tablets have human gum-health research involving lactoperoxidase. Findings in established periodontitis were less favorable. Whether another formula matches the active enzyme amount and reaction conditions cannot be established without product details.
Frequently asked questions about Lactoperoxidase
What does lactoperoxidase do in the mouth?
It runs saliva's chemical defense. Bacteria and the enzyme glucose oxidase produce hydrogen peroxide; lactoperoxidase uses that peroxide to turn thiocyanate (naturally present in saliva) into hypothiocyanite, a mild antimicrobial that suppresses acid-forming and gum-disease bacteria while sparing most friendly species. It's selective pressure, not a scorched-earth antiseptic.
Is there human evidence for lactoperoxidase supplements?
Yes. A 150-subject trial found lactoferrin + lactoperoxidase tablets (60mg + 7.8mg/day) significantly improved gum inflammation scores vs placebo over 12 weeks in healthy adults. A second trial in chronic periodontitis patients (100mg + 1.8mg ×3/day) found bovine lactoferrin levels rose in gum fluid but clinical markers didn't separate from control. Real but modest: best for gingival health, not established periodontitis.
Why do enzyme dental products pair LPO with glucose oxidase?
Because LPO needs hydrogen peroxide to work, and glucose oxidase generates it from glucose on the tooth surface. The pairing recreates the natural reaction chain. Supplying one enzyme without its fuel source is like shipping an engine without a spark plug.
Does it kill 'good' oral bacteria too?
That selectivity is the point of the system. Hypothiocyanite preferentially suppresses acid-tolerant pathogens (S. mutans-type metabolism) while friendly species tolerate it. The enzyme-toothpaste trials measured community shifts toward health-associated species rather than broad kill.
Is lactoperoxidase safe?
It's a protein your saliva already makes. In trials it's been well tolerated. As a bovine-milk-derived protein it's theoretically a dairy-allergen concern, though allergenicity at tablet doses appears minimal; strict dairy-allergic users should still note it.
References
- [1]Lactoferrin + lactoperoxidase tablets improved gingival index — 150-subject double-blind RCT (J Periodontal Res 2019)
- [2]LF+LPO tablets in chronic periodontitis — double-blind RCT, biomarker up but clinical parameters comparable (2011)
- [3]Enzyme-and-protein toothpaste shifted plaque microbiome toward health — randomized clinical study (Sci Rep 2017)
- [4]Enzyme-and-protein toothpaste improved gingival health — 3-month RCT vs control dentifrice (J Dent 2019)
- [5]The significance of the lactoperoxidase system in oral health — review (Int J Mol Sci 2019)
Products we reviewed containing Lactoperoxidase
Based on recorded labels or seller-described formulas. Inclusion does not establish a match to the strains, preparations or amounts studied here; check each review's disclosure limits.