9 months ago
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A common preservative used in food products from beer to sausages to cheese has the potential to interact with the human gut microbiome in unexpected and perhaps damaging ways, according to a new study.
These latest findings, from researchers at the University of Chicago and the University of Illinois at Urbana-Champaign, raise more questions about whether or not preservatives intended to kill pathogens on food might also be harming our internal bacteria mix.
"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," says microbiologist Zhenrun Zhang, from the University of Chicago.
"Even though it might be very effective in preventing food contamination, it might also have a greater impact on our human gut microbes."
Belonging to a class of preservative called lantibiotics, nisin is a protein containing unusual amino acids that affect microbial function without directly harming animals. Here, Zhang and his colleagues referenced genetic databases to cook up six nisin-like substances, which were then tested in a laboratory against both beneficial and harmful bacteria from the human gut.
Each lantibiotic produced different results, but they were all observed to affect both dangerous bacteria (pathogens) and microbes that help to maintain a healthy gut (commensal bacteria).
We're still a long way from being able to say that food preservatives are harmful to our stomachs, but the research does show that these chemicals have the potential to interfere with a healthy gut microbiome in ways that we perhaps hadn't anticipated.
"This study is one of the first to show that gut commensals are susceptible to lantibiotics, and are sometimes more sensitive than pathogens," says Zhang.
"With the levels of lantibiotics currently present in food, it's very probable that they might impact our gut health as well."
Over the years, additives like salt or alcohol have been replaced by more exotic ingredients as ways of keeping food fresh and lasting for longer, essentially by stopping bacteria and mold from spreading easily, spoiling the food.
And there is a growing amount of recent research suggesting that the ways in which we treat and process our food isn't doing our health any good. At the very least, it's worth looking at the balance of good and bad bacteria more closely.
Bear in mind that nisin-like lantibiotics are also produced naturally by the human gut, but whether the increased quantities provided by processed foods are indirectly causing harm remains to be seen.
"It seems that lantibiotics and lantibiotic-producing bacteria are not always good for health, so we are looking for ways to counter the potential bad influence while taking advantage of their more beneficial antimicrobial properties," says Zhang.
The research has been published in ACS Chemical Biology.
