Nutrition studies are increasingly exploring the health benefits from friendly microbes found in food. A new study coauthored by a University of Nebraska–Lincoln food scientist provides the first large-scale estimate of Americans’ consumption of those microbes.

The findings, recently published in the Journal of Nutrition, pave the way for follow-up research to understand the relationship of live microbe consumption and potential health and immune benefits.

“Our ultimate goal is to determine if there are associations between public health and consumption of foods that contain high levels of microbes,” said coauthor Robert Hutkins, Khem Shahani Professor of Food Science and Technology at Nebraska.

The human intestinal tract is home to trillions of bacteria, many of which play a critical role in keeping people healthy. They help digest food, keep pathogens at bay, produce vitamins and other beneficial metabolites, and enhance immune system function. The study of the gut microbiome is now front and center for biomedical, nutrition and food science researchers.

In this study, Hutkins and his coauthors analyzed national data on more than 9,000 foods consumed by nearly 75,000 American adults and children. First, the researchers estimated the number of live microbes per gram for all the foods. Next, they classified each food as containing low, medium or high levels of microbes. Foods in the low category were mostly processed or heat-treated foods. Medium category foods were mainly fresh fruits and vegetables. The foods in the high category that contained the most live microbes were fermented foods such as yogurt, cheese and fermented vegetables.

The researchers used the National Health and Nutrition Examination Survey food consumption database to calculate how much of the microbe-containing foods children and adults were consuming. About 26% of adults and 20% of children consumed foods with high levels of microorganisms, and both children and adults increased consumption of these foods over the past 18 years.

Future research, the scientists said, should focus on “prospective and randomized controlled trials to determine if there are quantifiable health benefits from consuming living microbes.”

Although consumers are rightly concerned about food safety, Hutkins emphasized that the vast majority of microbes in foods are simply normal members of the food ecosystem, and many are beneficial to health. As the authors noted, “exposure to nonharmful microbes is an important, beneficial source of microbial stimuli for the immune system.”

The research was funded by the International Scientific Association for Probiotics and Prebiotics and included the National Institutes of Health and academic researchers from the United States and Ireland.

“For nearly 20 years, the Institute of Agriculture and Natural Resources has provided funding for our gut health research program in Nebraska,” Hutkins said.

Along with philanthropic support from private donors and the University of Nebraska Foundation, IANR played a major role in establishing the Nebraska Food for Health Center in 2016. The center has “helped us make strong and productive alliances and collaborations” with the University of Nebraska Medical Center and University of Nebraska at Omaha, Hutkins said.

Hutkins’ personal interest in food science began during his days as an undergraduate at the University of Missouri.

“I had an interest in food but didn’t realize food science was even a major,” he said. “I was immediately drawn to the field.”

He later came to realize that “microbes in fermented foods did more than enhance the flavor, aroma, appearance and texture; they also had a major role in human health.”

Because cooking — and eating — are among his hobbies, studying food microbes has proven to be “a perfect recipe for mixing academic and personal interests.”

Thanks to sophisticated molecular and computational tools, “the science of fermented foods has experienced a research renaissance,” Hutkins said. “Understanding the health implications is now driving much of this research, including work being done right here at UNL.”