Study: Common food preservative harms ‘good’ gut bacteria

UH-Maui College team focused on probiotic-rich fermented foods

A University of Hawaii Maui College research team has found that a common food preservative killed or inhibited beneficial bacteria found in fermented foods and the human gut, according to an announcement.

The study focused on “good” bacteria naturally found in the human microbiome. These bacteria also are in fermented products rich in probiotics, such as yogurt, kimchee and kombucha. Numerous studies have pointed to the positive health benefits of such bacteria to the human immune system, diet quality, metabolic profiles and overall health, the announcement says.

A public presentation of “The Human Microbiome in Disease and Health” is scheduled for 5:30 p.m. Wednesday at the college’s ‘Ike Le’a Building, Room 144.

The college’s research team discovered that sulfites in food preservatives had a negative impact on beneficial bacteria, even when tested at levels generally regarded as safe by the U.S. Food and Drug Administration.

Genetics professor and lead researcher Sally Irwin said increasing evidence shows a direct correlation between diseases and alterations in the human gut and mouth microbiomes. Food preservatives may be partly to blame.

“As a geneticist and professor of microbiology, I have been interested in the human genome and microbes and their combined influence on human disease and health,” Irwin said. “Studies show a significant increase over the past 40 years in food allergies, obesity and metabolic disorders that have a direct correlation to disbiosis, or changes in the microbiome.

“In trying to understand what in our environment may be causing this change, the use of many food preservatives and their effects on beneficial bacteria came to mind.”

Irwin said overuse and misuse of antibiotics have been linked with having a significant impact on the human microbiome, but the UH-Maui College study was the first food preservatives have been tested for their effects on beneficial bacteria.

Irwin’s team included chemistry lecturer Peter Fisher and students Emily Graham, Ashley Malek and Adriel Robidoux.

According to the announcement, the students were exposed to lab work and overcoming the obstacles of research, such as how to ask questions and when to question the answers.

“This is the best education I can give to future scientists,” Irwin said. “It has been exciting and incredibly satisfying for me and the students to present a significant piece of research that others in the scientific community can build upon.”

The team aims to continue studying the effects of sulfites and other food preservatives in the lab and in living organisms, such as mice.

“We have started some preliminary work looking at the effects of sulfites on enzymes found in human saliva and commensal mouth bacteria,” Irwin said. “We would like to collaborate with another lab to do some mouse studies or use an artificial gut environment to look at effects on a mixture of bacteria.”

Irwin began preliminary work on this area of research at the Buck Institute for Research on Aging in Novato, Calif., during a 2014 sabbatical. Her research at UH-Maui College has been supported financially by the Hawai’i IdeA Network of Biomedical Research Excellence. The network is funded by the National Institute of General Medical Sciences at the National Institutes of Health.

Irwin also is an adjunct professor in the Cell and Molecular Biology Department at the UH-Manoa John A. Burns School of Medicine.

Her team published “Sulfites inhibit the growth of four species of beneficial gut bacteria at concentrations regarded as safe for food” in PLOS One, a multidisciplinary open access journal available online at journals.plos.org/plosone/article?id=10.1371/journal.pone.0186629.

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