“Every kind of living thing is dependent on communities of microbes we call microbiomes, and that includes humans,” says Lita Proctor. “Without bacteria, viruses, fungi, and other microorganisms, there wouldn’t be life on earth, and we wouldn’t be here.”
Proctor is director of the Human Microbiome Project, an eight-year research mission of the National Institutes of Health to explore the role of the microbiome in human health and disease.
“It’s hard to wrap our heads around the idea that microbes also play a major role in supporting our health,” Proctor explains. “That’s because so much of our human history of exposure to bacteria and viruses has been through infectious diseases and plagues.”
The microbes in and on our bodies break down undigested food, make vitamins, prime our immune system, secrete neurotransmitters that allow nerve cells to communicate with each other, help defend us against invading bugs, and more.
Our largest and most complex microbiome
That’s the one in our large intestine. “The average adult carries three to five pounds of microbes there,” notes Proctor.
Our fingers, hands, ears, navels, toes, mouth, and other nooks and crannies each have their own unique community of bacteria, viruses, and yeasts.
The best microbiome?
“There is no one healthy microbiome,” says Elisabeth Bik, of Stanford University. “There’s a huge variety of microbiomes among healthy people.” Bik publishes microbiomedigest.com, a website that updates investigators on new research.
What’s more, a healthier gut microbiome has many families of microbes. But for the vaginal microbiome, less diversity seems to be healthier. “This drives researchers crazy,” says Proctor, “because they want clear rules of the road.”
The best food for your gut microbiome
“Eating dietary fiber is associated with a very different microbiome, one that’s richer, with a higher number of bacterial species compared with eating a low-fiber diet,” says Bik.
“But you can’t get the fiber from a drink or a pill,” notes Proctor. “You have to present your microbes with a diverse array of fibers from a lot of different plant materials, such as beans and green vegetables.”
Think of yourself as a zookeeper for the community of little creatures inside you, says Bik. “Eating fiber is good not just for us: It also keeps them happy.”
Your gut microbiome changes as you age
It gets “noisier,” says Proctor. “We find less diversity—fewer families of microbes—in the microbiomes of people 65 and older, and there’s a lot more variability between older people than between younger folks.”
That could be the result of repeated antibiotic use, says Bik. “Or maybe they’re eating softer, less fibrous food or spending less time outdoors exposed to microbes.”
The bottom line:
Don’t cut back on fiber-rich plant foods as you get older, says Proctor. Your healthy gut microbiome needs that fiber.
Find this article about your microbiome interesting and useful? Nutrition Action Healthletter subscribers regularly get sound, timely information about how nutrients can affect their health. They also receive science-based advice about diet and diabetes, heart disease, cancer, osteoarthritis, and other chronic diseases; delicious recipes; and detailed analyses of the healthy and unhealthy foods in supermarkets and restaurants. If you’re not already subscribing to the world’s most popular nutrition newsletter, click here to join hundreds of thousands of fellow health-minded consumers.