Common Preservative May Harm Your Gut

A common food preservative may be damaging our gut health, scientists have warned.

Nisin is a popular antimicrobial preservative used in everything from beer to cheeses and dipping sauce. It is made naturally by bacteria to eliminate competition from other microbes by killing them. Compounds like this are often called "lantibiotics" because they are made of special bacteria-derived molecules called lantipeptides. However, while these are very effective at eliminating food-borne diseases, they may also be damaging the "good" microbes in our gut.

"Nisin is, in essence, an antibiotic that has been added to our food for a long time, but how it might impact our gut microbes is not well studied," Zhenrun "Jerry" Zhang, a postdoctoral scholar in the lab of Eric Pamer at the University of Chicago, said in a statement. "Even though it might be very effective in preventing food contamination, it might also have a greater impact on our human gut microbes."

These "good" bacteria—known collectively as the gut microbiome—are known to play an important role in everything from digestion to immunity and mental health, so killing them off can have serious consequences for our overall well-being. Killing off the good bacteria can also provide an opportunity for "bad" bacteria to take over the gut, as there is less competition with other microbes for the limited space and resources.

Interestingly, some of these "good" gut bacteria can also produce lantibiotic compounds, although this is usually in very small amounts.

In their study, published in the journal ACS Chemical Biology, Zhang and his colleagues isolated these gut-derived lantibiotics and tested how they might interact with disease-causing microbes as well as the good bacteria in our gut. What they found was that the good gut microbes were just as vulnerable to lantibiotics as the "bad" microbes that cause disease.

"[Our] study is one of the first to show that gut commensals are susceptible to lantibiotics, and are sometimes more sensitive than pathogens," Zhang said. "With the levels of lantibiotics currently present in food, it's very probable that they might impact our gut health as well."

This work builds on previous research into the links between nisin consumption and changes in the gut microbiome. In a study published in the journal Nature Scientific Reports, researchers from Ireland's University College Cork found that even low concentrations of nisin can travel through the gastrointestinal tract and modify the gut microbiome in the lower intestine.

However, they also found that these changes were reversible, with normal microbiome populations returning within three days of nisin consumption.

Is there a health problem that's worrying you? Do you have a question about the gut microbiome? Let us know via health@newsweek.com. We can ask experts for advice, and your story could be featured on Newsweek.