Nisin
A bacterial peptide approved for one job in American food law, and studied mostly in cows
Nisin is a 34-amino-acid peptide made by Lactococcus lactis, with unusual sulphur-containing rings that make it stable. US law permits it for one purpose: stopping botulism spores growing in pasteurized cheese spreads. Its medical research is mostly udder infections in dairy cattle.
What is it?
Nisin binds lipid II, the molecule bacteria use to build their cell wall, and then punches pores through the membrane. Lipid II is the same target vancomycin uses, which is part of why it keeps being revisited as resistance to older drugs spreads.
Its legal position in the United States is narrower than the phrase food preservative suggests. 21 CFR 184.1538, read on October 1, 2026, affirms nisin preparation as generally recognized as safe for one use: as an antimicrobial to stop Clostridium botulinum spores growing in pasteurized cheese spreads, at a level giving no more than 250 parts per million in the finished product. That regulation dates from 1988 and was last amended in 2023. It is not a drug and not a dietary supplement.
The clinical literature is dominated by mastitis in dairy cows, where an intramammary nisin infusion matched an antibiotic for cure rate. The one study in humans treated eight breastfeeding women.
Reviews describe a longer list of possibilities, from biofilms to tumour cells, which remain laboratory findings rather than treatments.
At a Glance
Every value in this table is printed from the Grey Peptides dataset, the same record the compound explorer and comparison tool read, so the three can never disagree.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Published Research
These are the studies in people and animals, read from their PubMed abstracts, with the US status taken from the regulation read on October 1, 2026.
Eight women with staphylococcal mastitis
Eight breastfeeding women with staphylococcal mastitis were randomised to a nisin solution applied to the nipple and areola for two weeks, or the same preparation without nisin. Staphylococcal counts in breast milk fell in the nisin group (3.22 against 5.01 log10 CFU/mL at day 14), and the signs of mastitis cleared in that group while persisting in the controls.
As good as an antibiotic in dairy cows
In 92 cows with 107 infected quarters, an intramammary infusion of 2,500,000 IU of nisin gave a clinical cure rate of 90.2% against 91.1% for gentamicin, with no difference in bacteriological cure (60.8% against 44.6%).
In chicken feed, against an ionophore
Seven hundred and twenty broiler chicks were fed nisin at four levels, salinomycin, or neither. Nisin changed the gut's bacterial enzyme activity and microbial ecology and improved growth performance, which the authors compare with the ionophore in routine use.
A new natural variant from human skin
Nisin J, a 3,458-Da variant with nine amino acid changes from nisin A, was isolated from Staphylococcus capitis taken from human skin. It killed a range of gram-positive pathogens including MRSA and Cutibacterium acnes.
What else has been proposed
A review of nisin beyond food preservation: activity against gram-positive and some gram-negative pathogens, anti-biofilm properties, synergy with conventional drugs, possible immune effects, and selective toxicity toward cancer cells in laboratory work.
Side Effects & Contraindications
Reported Side Effects
Nisin is eaten in cheese spreads and has been applied to skin in one small study.
Contraindications & Cautions
It is a food additive, not a medicine.
Legal Status
Legal in food, for one purpose.
Frequently Asked Questions
?What is nisin used for?
In US law, one thing: stopping Clostridium botulinum spores growing in pasteurized cheese spreads, at no more than 250 parts per million. Everything else is research.
?Is nisin an antibiotic?
It kills bacteria by the same route vancomycin uses, binding lipid II, but it is not approved as a drug anywhere for human infection. Most of its treatment research is in dairy cattle.
?Has nisin been tested in people?
In one small study: eight breastfeeding women with staphylococcal mastitis, where applying it to the skin lowered bacterial counts in milk and cleared the signs of infection.
?Is it a dietary supplement?
No. It is a food additive affirmed as generally recognized as safe for a specific food use, which is a different legal category from a supplement and from a drug.
References
- [regulation] 21 CFR 184.1538, Nisin preparation, read in the eCFR on October 1, 2026 (53 FR 11250, April 6, 1988; last amended 88 FR 17724, March 24, 2023).
- [pubmed] Fernández L, et al. "The bacteriocin nisin, an effective agent for the treatment of staphylococcal mastitis during lactation." J Hum Lact, 2008;24(3):311-6. PMID: 18689718.
- [pubmed] Cao LT, et al. "Efficacy of nisin in treatment of clinical mastitis in lactating dairy cows." J Dairy Sci, 2007;90(8):3980-5. PMID: 17639009.
- [pubmed] Józefiak D, et al. "Dietary nisin modulates the gastrointestinal microbial ecology and enhances growth performance of the broiler chickens." PLoS One, 2013;8(12):e85347. PMID: 24376878.
- [pubmed] O'Sullivan JN, et al. "Nisin J, a Novel Natural Nisin Variant, Is Produced by Staphylococcus capitis Sourced from the Human Skin Microbiota." J Bacteriol, 2020;202(3). PMID: 31740495.
- [pubmed] Shin JM, et al. "Biomedical applications of nisin." J Appl Microbiol, 2016;120(6):1449-65. PMID: 26678028.
- [pubmed] Breukink E, et al. "Lipid II as a target for antibiotics." Nat Rev Drug Discov, 2006;5(4):321-32. PMID: 16531990.
Sources & Citations
The US status comes from 21 CFR 184.1538, read in the eCFR on October 1, 2026; studies from their PubMed abstracts the same day.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Consult a licensed healthcare provider before making health decisions.