How important are microbes in the human diet? And does it matter which ones we eat?
“Maybe we’re not too far from proving the following; the dietary guidelines, the My Plate guidelines, should include fermented foods, including those that contain live microorganisms, as part of a healthy diet,” says Bob Hutkins, PhD, a professor at the University of Nebraska (and TFA Advisory Board member). Hutkins explored this hypothesis during his standing-room only presentation at FERMENTATION 2022 titled The Microbes We Should (or Shouldn’t) Be Eating.
He estimates, just like the daily fiber recommendations were granted based primarily on epidemiological studies, fermented foods are going through the same process. And one day there may be a daily fermented food recommendation.
Why Should We Be Eating Live Microbes?
Highly processed foods, prolific use of antibiotics, and overly hygienic environments have resulted in significantly less exposure to microbes. This includes those microbes that help to maintain a healthy gut microbiome and that keep our immune system functioning properly. Indeed, according to the so-called Old Friend’s Hypothesis, exposure to microbes is necessary for proper development of the immune system. This is especially true for Western countries. One highly-cited study published in Lancet found Inflammatory Bowel Diseases (IBDs) like Crohn’s Disease and Ulcerative Colitis — “are predominantly associated with Western populations. You rarely see these diseases in other parts of the world,” Hutkins says.
“In the Covid era, we have certainly learned that preventing infectious diseases remains a major challenge, and being a bit germophobic is understandable. Certainly, modern food technology that includes pasteurization has significantly reduced pathogen risk, improved food safety, enhanced shelf life, and reduced food waste. Nonetheless, our environment has often become too clean, too hygienic and we are no longer exposed to microbes,” he adds.
Another study based on research in Finland found the Old Friend’s Hypothesis holds true for development of allergies, asthma, and eczema. As the authors noted “changes in environment and lifestyle, affecting microbial exposure and immune regulation, seem to play a major role in the so-called post-war allergy epidemic”. Indeed, in a 2002 editorial in the New England Journal of Medicine, three “old-school” lifestyle approaches were mentioned for protecting against the development of allergies: supplementing with lactobacillus (the bacteria found in fermented foods), owning a dog in your home and attending daycare.
Consuming Live Microbes Benefits Human Health
To address this situation, Hutkins and other food scientists are proposing adding fermented foods to the Recommended Dietary Guidelines, along with the daily dose of nutrients and vitamins.
“One of the main challenges however, will be to distinguish between nutrients and microbes,” Hutkins says.
The International Scientific Association for Probiotics and Prebiotics (ISAPP) has explored this further. A panel of ISAPP microbiologists, nutritionists, doctors and statisticians (including Hutkins) used the National Health and Nutrition Examination Survey (NHANES) to deep dive into the American diet. The NHANES database catalogs what adults and children are eating, then collects health indicators for associated diseases.
ISAPP researched the estimated live microbes in foods to find sufficient evidence that a live dietary microbe intake should be a part of a dietary recommendation. It was a big undertaking, since there are 9,388 foods inNHANES. ISAPP ranked each food’s microbial count. They found microbial count was low for processed, heat-processed foods, medium level for fresh fruit and vegetables and high for fermented foods, like fermented dairy (yogurt, fresh cheese) and fermented vegetables.
“Ninety-six percent of the foods we eat are in the low” count for microbes, he said. “Hardly any were in the fermented category, around one percent.”
Still, not all live microbes are the same. The microbes considered healthy – lactic acid bacteria and bifidobacteria – are only dominant in fermented foods. Most of the live microbes consumed in the average diet are proteobacteria from fresh fruits and vegetables.
The Institute for the Advancement of Food and Nutrition Sciences, which catalogs nutrition labels for all USDA food data, now has a space for a brand to enter the amount of live microbes in their product. There’s a dropdown menu to add genus and species of a probiotic strain, too.
“This new effort is a way to introduce the live microbes in the database,” Hutkins says, noting a company would have to enter it voluntarily. “They’re offering a noncompetitive, objective, transparent mechanism for stakeholders to understand live microbe intake and eventually link intake to health outcomes.”