Evidence continues to emerge of the unsafe effects of preservatives on our gut microbiomes.

The latest, from the University of Chicago in 2024 (1), points to points to a group of food preservatives that are actually antibiotics - called lantibiotics – which kill off pathogens but also kill the commensal bacteria which keep us healthy. Commensals provide important benefits to the body by breaking down nutrients, producing metabolites, and - importantly - protecting against pathogens.

“If too many commensal bacteria are indiscriminately killed off by antimicrobial food preservatives, opportunistic pathogenic bacteria might take their place and wreak havoc - a result no better than eating contaminated food in the first place” (2).

Nisin is a popular lantibiotic used in many foods, particularly in cheese in Australia, but also in foods from beer and sausage to dipping sauces. In 2016 we pointed out to regulators some Russian research that said “nisin can promote resistance and increase the risk of transfer of antibiotic resistance to representatives of the intestinal microflora, as well as speeding up virulence and pathogenic potential of microorganisms which cause food borne illnesses (3).” No action was taken. More

In fact, it is hard to find science papers which conclude there is no effect from preservatives but these facts (eg 4-6) are completely ignored by food regulators, who continue to allow deliberately narrow ‘safety’ assessments which do not look at effects on the microbiome, nor require testing on the combinations of additives often used in foods.

The Food Intolerance Network now shows these additives as CAUTION in the hugely popular (more than 750,000 views!) complete list of food additives.


1. Zhenrun J. Zhang et al, Activity of Gut-Derived Nisin-like Lantibiotics against Human Gut Pathogens and Commensals, ACS Chemical Biology (2024).

2. Common food preservative has unexpected effects on the gut microbiome

3. Where to find Nisin 234 and concerns about antibiotic resistance (2016) 234Nisin.pdf

4. Preservatives must change the microbiome

5. Dementia - propionate preservatives: French study confirms the link

6. Diet first for ADHD