E235 – Natamycin - Is It Safe? Side Effects & Regulation

Safety grading GREEN – SAFE

E235 is best rated GREEN – SAFE because its approved food uses are narrow, dietary exposure is low, and the main safety reviews support a margin for normal consumption. Natamycin is mainly a surface antifungal used on cheese rind and some cured-sausage casings, not a preservative that should be mixed broadly through foods. The main caveat is that broader uses creating higher gut exposure would be more controversial than the tightly restricted uses authorised today (JECFA, 2024; EFSA ANS Panel, 2009; DOI: 10.2903/j.efsa.2009.1412).

Acceptable Daily Intake

JECFA has re-affirmed an ADI (Acceptable Daily Intake) of 0–0.3 mg/kg body weight per day for natamycin. For a 70 kg adult, that equals 21 mg per day. For a 20 kg child, it equals 6 mg per day. That is not a target intake. It means lifelong intake at or below that level was not considered a toxicological concern. EFSA did not set its own ADI in 2009 because it considered the database too limited, but it still concluded that exposure from restricted surface treatment was not of safety concern. EFSA’s high-end estimate was below 0.1 mg/kg bw/day for children, and natamycin is poorly absorbed after oral intake, which adds a safety buffer for normal food use (JECFA, 2024; EFSA ANS Panel, 2009; DOI: 10.2903/j.efsa.2009.1412).

Study basis or key toxicological reasoning

JECFA’s 2024 re-evaluation noted NOAELs (No Observed Adverse Effect Levels) from new rat studies of 42 mg/kg bw/day in a 13-week dietary study and 26 mg/kg bw/day in a 1-year dietary study. With a 100-fold uncertainty factor, those data were considered supportive of the existing ADI. Older toxicology work on pimaricin, another name for natamycin, also pointed to low oral toxicity, and later reviews of the dossier describe reproductive and developmental NOAELs around 50 mg/kg bw/day in rats without a clear teratogenic signal at tested doses (Levinskas et al., 1966; PMID: 5296925; DOI: 10.1016/0041-008X(66)90105-0; Meena et al., 2021; PMID: 34868698; DOI: 10.1007/s10068-021-00981-1; JECFA, 2024).

The main uncertainty is not ordinary cheese-rind exposure but broader or more bioavailable uses. EFSA highlighted limitations in the older database, and a mouse study testing preservatives at three times the ADI found that natamycin affected glucose tolerance after chronic exposure. A separate review warned that homogeneous use in foods such as yoghurt or beverages could create a different resistance and gut-exposure scenario than restricted surface treatment. Those caveats matter, but they do not overturn the low-risk picture for authorised surface uses (Li et al., 2022; DOI: 10.1038/s41538-022-00158-y; Dalhoff and Levy, 2015; PMID: 25862309; DOI: 10.1016/j.ijantimicag.2015.02.011).

Side effects

No specific side effects are expected at normal food-use levels. Approved uses keep exposure relatively low and mostly limited to treated surfaces.
Surface-restricted use matters. Natamycin is more reassuring when it stays a rind or casing preservative than when it is mixed throughout a food.
High experimental exposure can raise microbiome or resistance questions. That concern comes mainly from animal studies and broader-use scenarios, not from standard cheese-rind use.
Removing the rind or sausage casing can further reduce exposure. That is useful for people who want to minimise antimicrobial preservatives.

Should You Avoid This Additive?

Most people do not need to avoid E235 when it is used in the limited way regulators usually allow it. Occasional intake from treated cheese rind or sausage casing is not where the main safety concern lies. Avoidance makes more sense for people who prefer to minimise antimicrobial preservatives or who simply do not want antibiotic-like additives in the diet. The bigger concern is expansion into broader food uses, not the restricted surface treatment itself.

Common Uses

Cheese rind. It helps suppress mould and yeast growth on the outside of hard, semi-hard, and semi-soft cheeses.
Dry-cured sausage casings. It is used on the casing surface to reduce fungal spoilage.
Protective surface coatings. It may be applied in dips, sprays, or edible coatings that keep the effect near the surface.
Specialty dairy and meat preservation. It is valued where fungal control is needed without acting as a broad antibacterial preservative.

Common names / Synonyms

Natamycin.
Pimaricin.
E235.
Preservative: natamycin.
Antifungal preservative.

What is it?

Natamycin is a polyene macrolide antifungal produced by fermentation of Streptomyces species. Unlike many preservatives, it mainly targets moulds and yeasts rather than bacteria. Its action is linked to binding ergosterol in fungal cell membranes, which interferes with fungal growth and spore germination. That makes it useful on the surface of foods vulnerable to fungal spoilage, especially cheeses and cured meats. Natamycin is mainly a surface preservative. It stays mostly on the outside of food and only a small amount is absorbed by the body after it is eaten.

That profile explains why E235 has a narrower role than preservatives such as sorbates or benzoates. Food-grade natamycin is produced under controlled fermentation and purification conditions and is usually applied in coatings, dips, or sprays. Its strengths are targeted antifungal activity and limited absorption. Its weakness is that broader, mixed-through uses would change the exposure pattern and raise more questions about microbial selection pressure in the gut (Meena et al., 2021; PMID: 34868698; DOI: 10.1007/s10068-021-00981-1; Dalhoff and Levy, 2015; PMID: 25862309; DOI: 10.1016/j.ijantimicag.2015.02.011).

Where it’s allowed (EU vs US)

In the European Union, E235 is authorised for external treatment of certain cheeses and for surface treatment of dried cured sausages, with strict depth and surface limits. In the United States, natamycin is permitted under 21 CFR 172.155 for use on cheese as an antimycotic at up to 20 mg/kg in the finished product. In both systems, natamycin is allowed, but its food use is deliberately narrow rather than general.

E235 – Natamycin