Inside our digestive tract is a giant and complex bacterial community. Called the gut microbiome, this ecosystem of organisms has been found to potentially have broad systemic effects across our entire body, from playing a part in PTSD and Alzheimer's to influencing the success or failure of cancer treatments. A new study from a team at the University of Massachusetts Amherst has found that some non-toxic food preservatives, added to food for antimicrobial properties, could be unexpectedly and adversely interacting with out gut microbiome.

It is becoming increasingly clear that our gut microbiome exerts a broad influence on our overall health and wellbeing. While much research has focused on how dietary factors and interventions can effect the diversity of gut bacteria there is little understanding into how our many food additives influence the microbiome.

A significant fraction of food additives approved for use in the United States are classified as anti-microbial agents. These additives are designed to reduce food spoilage by inhibiting the growth of several microorganisms.

This new study examined the effects of a specific anti-microbial food preservative called biopolymer ε-polylysine on the gut bacterial diversity in mice. The results interestingly showed that polylysine did certainly alter the diversity of microbes in the mice but over a 15-week study period it was observed that this alteration was oddly transient, with diversity returning to normal after a period of continuous feeding.

"Starting at about week five it changed but by about week 9 it was back," says David Sela, one of the authors of the study. "The microbes' functions shifted, which is really interesting that you can have different populations doing different things. Typically the microbiome will stay shifted when you give antibiotics, for example, so our results suggest that somehow there is an adaptation to the food-grade preservative."

The study does not presume any potential health effects stemming from this microbiome alteration, but it raises some compelling questions regarding influence of food preservatives that previously have been assumed to be safe. It is important to note that this is a small study in a relatively new research area, but the increasing body of evidence highlighting the broader impact of gut bacteria on a person's well being suggest this is a phenomenon worth investigating.

"We're certainly interested in looking into it further," adds Sela. "We do not know enough about what preservatives do to the microbiomes in the gut."

The study was published in the journal Science of Food.