How Good Gut Bacteria Could Transform Your Health

By Gretel H. Schueller, "The Wild World Within," July/August 2014

Scientist Jeff Leach is studying gut microbes that have the potential to improve our weight, mood, allergies, heart and more.

"Catching up on my magazine subscription and just read this article - WOW! Thank you to Jeff for his work, thank you to Gretel for writing this article, and thank you to Eating Well for publishing it. "

Barefoot and coated in fine desert dust, Jeff Leach hops around the fire, adjusting logs. Its roaring glow provides the only light as the sun sinks behind the Chisos Mountains and the desert air cools.

It’s dinnertime here in Terlingua, the tiny town in southwest Texas that Leach sometimes calls home. We’ve just finished piercing roughly chopped pieces of leek, onion, beef, green peppers and garlic onto metal skewers, and Leach works at balancing them over the fire. Juices sizzle and the roasting aroma makes my mouth water.

“Have you ever held a colon in your hands?” he asks. Whoa…

Talk of belly bacteria, stool samples, bowel movements or your colon isn’t supposed to be part of polite (or appetizing) dinner conversation. But eating with Leach requires new rules of etiquette. Actually, it requires rethinking a whole slew of “rules.”

Once you get talking to Leach and his research colleagues around the world, you quickly realize it’s not just about changing dinner-table etiquette—we may be changing how we talk about health entirely. It all centers on the trillions of bacteria living in our gut.

We are more microbe than human. We each carry an estimated four to ten times more bacterial cells than human cells. If you could mush all the bacteria together they’d be the size of a basketball and weigh about three pounds.

The invisible world of bacteria that live on and in us is called the microbiome; the gut microbiome is the term for the diverse collection living along our intestinal tract, where the bulk of our tiny partners make their home.

Research on the gut microbiome has exploded over the past few years. This bold new frontier may just provide the string theory of all human disease. “Name just about any ailment plaguing us and you’ll find some ­researchers discovering the microbial angle for a connection,” says Leach, whose latest book, Bloom: Reconnecting with Your Primal Gut in a Modern World, is due out this fall. Recent studies have implicated gut microbes in everything from autism and depression to cancer and diabetes to heart disease and obesity. “It’s a water­shed ­moment for human health,” says Leach.

He should know. Leach—with his frenetic energy, powerful charisma and uncanny ability to step back and connect diverse dots—is one of the most visible leaders of the gut-health movement. In 2012, Leach founded the Human Food Project, a global effort to study how diet affects the microbial world within us.

A major arm of that is the American Gut Project, thought to be the largest microbiome project in the world, co-led by Rob Knight, Ph.D., a professor at the University of Colorado’s BioFrontiers Institute and a Howard Hughes Medical Institute Early Career Scientist. The goal is to map the diversity of the ­human gut—and tease out patterns shaped by diet, age and lifestyle to understand the factors most important for a healthy gut microbiome.

So far, more than 7,000 people have signed up for the gut project. After completing a questionnaire and a 7-day food journal, and paying $99, participants send a fecal sample to be analyzed.

Some of the questions might seem odd: How many different plants do you eat in a week? Born by C-section? Own a pet? Used an anti­biotic in the past month?

But Leach explains that all of these things affect your microbiome. And what he and his colleagues are finding is that Americans generally have less-diverse gut microbiomes than other populations. No one knows what the perfect gut microbiome should look like—or if there even is one. But one thing is clear: diversity is key. And we’re losing it.

Building the Microbiome

Until the moment we are born, we are still 100 percent human. In other words, bacteria-free. Most of us get our first dose of microbes while traveling through the birth canal. The second big dose comes from breast milk. As babies grow, they pick up critters from dirt, pets, family members and friends. By age 3, the microbiome has pretty much set up camp.

But changing lifestyles are chipping away at that microbiome. Early studies indicate that children born by C-section—which reduces the microbes an infant is first exposed to—have a higher risk of celiac disease, obesity and type 1 diabetes. Add to that decreased breast-feeding and “our overzealous use of antibiotics,” says Leach, who compares what antibiotics do to the gut microbiome to clear-cutting a forest.

From birth to age 5, children receive more anti­biotics than during any other five-year period in their lives. One of Leach’s colleagues, New York University microbiologist Martin Blaser, M.D., believes antibiotics have “deranged” the micro­biome—even causing some species to go extinct—and that their overuse is why many health problems, including type 1 diabetes, obesity and allergies, are on the rise.

Numerous studies also show that scrubbing away our microbes may be weakening our bodies’ natural defenses—something Leach has experienced firsthand: 12 years ago, at age 2, his daughter was diagnosed with type 1 diabetes, an autoimmune disease.

“My daughter was born C-section—strike 1; breast-fed very short—strike 2; strike 3, she received antibiotics at a very young age; strike 4, she lived in an environment where we basically wet-wiped everything and bathed her twice a day.” Leach feels strongly that her disease is a by-product of our culture.

At the time, Leach, who has a Ph.D. in anthropology, was studying how ancient people acquired and cooked foods. “When my daughter was diagnosed, the only thing I could do was to try to under­stand why she was sick. I just started emailing microbiologists and asking questions.”

He learned that this autoimmune disease is an overreaction of the immune system. And the bulk of immune cells live in the gut.

So into the gut he went—and stayed.

His new focus is actually not that much of a leap from anthropology. “If microbiome research is anything, it’s anthropology—about how people interact with their environment,” notes Leach.

Here in this remote desert town, Leach’s life is a sharp contrast to his sanitized suburban past.

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