June 21, 2022 – What we eat affects the trillions of bacteria, fungi, viruses, and other germs that live in our digestive tract, referred to as our gut microbiome by scientists. Some of the many roles of theses microbes inside our bodies include changing how the immune system functions and influencing physical and mental health.

Scientists know that certain dietary options like fermented foods, yogurt, and non-starchy fruits and vegetables help create a healthy mix of organisms in our gut.

But one thing about the gut microbiome has remained a mystery: How many immune-boosting microorganisms do people actually eat with all the foods they consume?

To figure this out, investigators estimated the number of microorganisms per gram in more than 9,000 foods. Foods with the highest levels of microbes included things known to promote a healthy microbiome, like yogurt, pickles, and kimchi. Foods with medium microbe levels included a wide variety of raw fruits and vegetables.

Then, to see how many people ate foods packed with microorganisms, scientists looked at detailed dietary data collected from 2001 to 2018 for almost 75,000 adults and children.

Overall, 26% of adults and 20% of children consumed foods with high levels of microorganisms, researchers reported in The Journal of Nutrition.

"When we think of microbes in our food, we often think of either foodborne pathogens that cause disease or probiotics that provide a documented health benefit," study co-author Colin Hill, PhD, of APC Microbiome Ireland at University College Cork, said in a statement.

But it's important to also explore microbes that we consume in fermented and uncooked foods, Hill said.

"It is very timely to estimate the daily intake of microbes by individuals in modern society as a first step towards a scientific evaluation of the importance of dietary microbes in human health and well-being," he said.

Show Sources

CDC, National Center for Health Statistics: “National Health and Nutrition Examination Survey.”

The Journal of Nutrition: “A Classification System for Defining and Estimating Dietary Intake of Live Microbes in US Adults and Children.”

EurekAlert!, American Association for the Advancement of Science (AAAS): “Quantifying the live microbes on your plate.”

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