Kombucha, kefir and kimchi: keep your microbes happy
Good bacteria can keep our guts healthy and improve overall health, beginning with breast milk in infancy and continuing with a diet that includes fermented foods.
Humans have consumed live bacteria in fermented foods since ancient times. We’re accustomed to hosting these beneficial “bugs,” as Carolina microbiologist Andrea Azcarate-Peril calls them.
Yogurt, sauerkraut and beer are just a few fermented favorites that often appear on shopping lists and dinner tables.
Microorganisms hitch a ride on these foods and enter our guts, where some will find a permanent home and jobs keeping us healthy. Others enjoy a temporary stay, then continue their journey. All, along with the other bacterial residents, make up the gut microbiome.
Probiotics: the good microbes
Good microbes are called probiotics, and when enough of them get together, the party starts. They begin doing things to help us, like producing substances that prevent or fight diseases or regulate body functions. Examples include Lactobacillus, Bifidobacterium and the yeast Saccaromyces boulardii.
The happiest probiotics are ones with plenty of prebiotics, food substances that humans don’t digest, to munch on. Prebiotics fuel beneficial microbial activities in the gut and include resistant starches in seeds, nuts, legumes and other fiber-rich foods.
Andrea Azcarate-Peril.
To answer questions about ways probiotics help us, the history of fermentation and how enriched foods shape digestive processes and improve our health, Azcarate-Peril and two other scientists recruited top researchers to share their expertise on human-bacteria interactions. The resulting new book is “Fermented Foods Feed a Healthy Gut Microbiota: A Nutrition Continuum.” Azcarate-Peril, an associate professor in the School of Medicine and director of the University’s Microbiome Core, edited the book along with Roland Arnold, professor of diagnostic sciences in the Adams School of Dentistry, and Jose Bruno-Barcena, associate professor of microbiology at North Carolina State University.
Roland Arnold.
“This book is really a first of its kind,” Azcarate-Peril said. “The concept that our microbiota need feeding or seeding is novel as are the book’s concepts on fermented foods as a source of microbes to ‘feed’ our microbiota, the mouth as a gatekeeper and the gut.”
A healthy microbiome benefits us
“Having a healthy gut microbiota is clearly beneficial for us,” Azcarate-Peril said. “We are in a symbiotic relationship with our associated microbes.”
Microbiota generate important substances for our body, such as vitamin B and neurotransmitters that make our nerves work, including Gamma aminobutyric acid, an amino acid that calms the nervous system. Microbes also combat and prevent the colonization of disease-causing bacteria.
While the book looks at how the bugs live, it also looks at how we kill them. One chapter describes the depletion of our gut microbiota through antibiotic overuse, leaving little or no defense against potentially pathogenic bacteria such as Clostridium difficile (C Diff).
Here are a few tips about probiotics and keeping our gut bugs happy.
Begin with breast milk
Breastfeeding infants establishes their healthy gut microbiota and sets the stage for healthy adulthood. Breast milk is the most complete source of nutrition for infants and their microbes, according to Azcarate-Peril.
“Scientists around the world recommend exclusively breast-feeding during at least the first six months of life, then begin supplementing with solid foods up to a year or two beyond,” she said.
Breast milk is also the main source of healthy microorganisms for infants and prebiotic human-milk oligosaccharides that help establish beneficial bacteria in the gastrointestinal tract.
The resulting healthy gut microbiota help babies develop a robust immune system and avoid allergies, infectious diseases, obesity and diabetes, and shape good brain development.
Shop the dairy aisle
Look for fermented dairy products such as kefir, yogurt and some cheeses to add microbial diversity to your life.
Many such microbes from dairy are either identical or share physiological traits with species known to promote good intestinal health. They include bacteria such as the yeast S. cerevisiae, used as a starter for kefir or koumiss, and gamma-aminobutyric acid, which can calm our nervous system and prevent seizures. Such bioactive components or active compounds can help you, so consider trying different products.
“For example, if you’re lactose intolerant, you can try yogurt. Bacteria should have consumed the lactose,” Azcarate-Peril said. “That transformation is not only physical, but it’s also chemical and provides other substances in the yogurt’s culture.”
Remember your fruits and vegetables
Fresh produce usually has some measure of good bacteria on the outside, even after washing. Also check store shelves for products such as fermented vegetables, miso and tempeh or veggie mixtures.
Research has proposed that plants pass on beneficial bacteria to their seeds, which then becomes part of the harvest for humans, Azcarate-Peril said.
Go easy on cleaning
Today’s hand sanitizers, scrubbed surfaces and processed foods eliminate good bacteria before they can reach us. That hyper-sanitization during the second half of the 20th century, combined with a western diet dominated by low fiber and refined carbohydrates, and antibiotic overuse to reduce infectious diseases, has led to an increase in chronic and autoimmune conditions. So consider cleaning less vigorously.
“We have to achieve a balance. I’m a microbiologist, and I hate hand sanitizers,” Azcarate-Peril said. “However, I’m not going to suggest that you eat raw chicken. So there’s a balance that includes our exposure to good bacteria.”
Cook at home and try fermentation
Cooking at home avoids processed food that’s been overcooked and sterilized to avoid pathogens like salmonella to the point that no beneficial microbes survive. That won’t happen at home. “When you wash a tomato and put it in your salad, it has small amounts of bacteria, maybe the right amounts to stimulate your immune system,” Azcarate-Peril said.
Consider home fermentation. Check the Web for how-to’s or find a cookbook. Determine what you need, such as starter culture and canning supplies, then give it a go. Keep it simple or try artisanal fermentation with different flavors and varieties of, say, kefir, kimchi, mixed vegetables or sausage.
Microbial exposure through your own cooking or fermentation recipes may help prevent problems such as irritable bowel disease and a reactive immune system.
Eat right as you and your microbiota age
It’s important to eat a diet that feeds prebiotics to your probiotics, especially as you age, to prevent the loss of diverse, beneficial bacteria.
How the gut ages has been difficult to research because of many factors such as diet changes, medication, frailty and life events that decrease microbiota diversity and increase disease-causing bacteria. But researchers speculate that during your adult years into old age, probiotics will contribute to your overall health and prevent disease.
“I’m very interested in aging because the beginning and the end of life is when the gut microbiota are most fragile,” Azcarate-Peril said. “As we deteriorate physically, our immune system deteriorates. We may reach an age when we have a problem with digesting food, so we lose the equilibrium and resiliency that we’ve had our whole life.”
Take care of your microbiome, and it will take care of you
In the book’s last chapter on diseases of western civilization, Emiliano Salvucci expands on his concept of the holobiome, which is you as a human individual, plus your associated microbiota. Despite differences in microbiomes from one person to the next, they mostly perform the same key functions. To keep ourselves healthy, we also need to keep our associated microbes healthy.
Azcarate-Peril, who has worked with probiotics for over 20 years, said that the concept of beneficial bacteria received little credence early on.
“When I started working with probiotics, a researcher would publish a paper and there was almost no impact in medical and biomedical communities,” she said. “Today, everybody is talking about how important it is to maintain healthy gut microbiota and the importance of keeping our bugs happy.”
