Holy crap! Microbiologists are going gangbusters discovering more and more about the human microbiome. If you haven’t heard of this new area of research you are in for a shock. Turns out that 90 percent of the cells of our bodies are bacteria! They are on our skin, in every bodily orifice, throughout our gut, and more. We are each home to 100 trillion bacteria—an amazing internal garden. How come this is news? In the past, scientists were limited to taking samples and swabs and growing them in a lab. The microbes they saw were the ones who liked growing on Petri dishes. Since DNA sequencing has become less expensive (biology being one of those currently impoverished branches of science), researchers have been able to sequence samples and get complete and accurate censuses of types and numbers of the tiny critters they contain. And wow—what an amazing world they have discovered!
A year ago I wrote about how being exposed to a diversity of bacteria from birth trains our bodies’ immune systems to distinguish dangerous bacteria from benign, and how infants and children who grow up on an old-fashioned farm, surrounded by a variety of plants and animals, are immune to allergies, asthma, and other autoimmune disorders. Amazing! And that obese twins inoculated with their thin twins’ microbiota lost weight. Even more amazing! There’s more—in a year, science has quickly progressed.
E. coli is a bacteria that happily reproduces in a petri dish—that’s
one reason why it’s famous. But there are countless other bacteria,
many of which scientists are just identifying now for the first time.
Over at the American Gut study, you can get your own microbiome checked. This project was co-founded by Jeff Leach. Eleven years ago, Leach and his wife had a daughter delivered by Cesarean section, who they raised in a super-clean suburban house with lots of antimicrobial soap, wipes, etc. She was diagnosed at age two with Type 1 diabetes. Leach, then an anthropologist, researched the cause of his daughter’s early illness and concluded that it was lack of contact with bacteria, which made him feel “guilty and angry.” Leach returned to school, got a master’s and PhD in microbiology, founded the American Gut project, and headed to Tanzania to study the microbiome of the Hanza, the last hunter-gatherer culture left in the world, with—ostensibly—the last “wild” human microbiome.
Since then, American Gut has tested thousands of people (and their dogs). I did it—with their kit, you track your diet for a week and send a sample of your poo. The results were fascinating (is this the newest form of navel-gazing?). My gut bacteria are normal (whew!) and similar to other subjects who don’t eat many processed foods (refined starches and sugars have a huge effect on gut biota). I am home to four rare types of bacteria, one of which hasn’t even been named! This makes me feel special—and a little concerned. My results will be added to their study data. The project is ongoing and you can participate, too.
New aspects of the microbiome are being discovered constantly! One amazing breakthrough is the discovery that wombs and fetuses are not sterile, as has been thought since the 1930s. There are plenty of bacteria in there, clustered in the placenta around the umbilical cord connection. And further, the bacteria of babies carried full term differed dramatically from that of babies born prematurely. Scientists don’t yet know why.
Another observation is that artificial sweeteners have a disruptive effect on the microbiome and the body’s ability to regulate blood sugar. Tests on mice show that microbiota under the influence of artificial sweeteners (saccharin, aspartame, and sucralose) developed a “marked intolerance to glucose,” which can lead to serious illnesses like Type 2 diabetes. Ironically, and dangerously, diabetics often use artificial sweeteners due to dietary restrictions.
Researchers have discovered that our gut microbiome changes composition and gene functions throughout the day, based on when we eat. When our habitual mealtimes change, as often happens when jet-lagged or doing shift work, our microbial mix changes to a combination that nurtures obesity and, again, impairs glucose responses. Stay tuned.
The combined length of the large and small
intestines in humans is about 25 feet.
Scientists may have solved the mystery of why people of western nations get colorectal cancer so much more frequently than residents of less-developed countries. High-fructose corn syrup and refined sugars supply microbes with a feast of carbohydrates, encouraging them to produce small molecules that cause colon cells to produce tumors uncontrollably. Given that colorectal is the third deadliest cancer and that nearly one in fifteen of us will get it, this is an important area of research indeed.
Another discovery is that our microbes can make a huge variety of small molecules that can be used for medications. Small molecules are important for communication between bacteria and us hosts (as above). Our bacteria are capable of making over 44,000 different small molecules, and some of them may lead to whole new kinds of medications.
Smelling money, multinational corporations like Nestlé (“the world’s leading nutrition, health and wellness company”) have become very interested. In January, Nestle Health Science invested $65 million in a startup company that promises to “restore the microbiome.” It’s stupifying—Nestlé, a company that proudly produces candy rich in high-fructose corn syrup and other refined carbs, is planning to sell us back our own microbes to cure the ills caused by their junk food!
There are, and will be, more and more companies selling probiotics and treatments based on this new, but incomplete, knowledge. The savvy person, and their biota, will be wary. It’s widely believed by microbiologists themselves that best way to sustain your internal garden is to get out in your backyard garden and get your hands dirty. Go easy on sanitizers and processed foods. Avoid antibiotics and avoid eating animals fed antibiotics. Hang out on farms with a variety of livestock. I think I like it.
Science News: I love this thin magazine, published by the nonprofit Society for Science and the Public. A great web site, too: sciencenews.org
Science: a fat magazine, most of which I don’t understand. But great for research. Sciencemag.org
Human Food Project and American Gut Project: ongoing research with a great web site: humanfoodproject.org.
Maria Reidelbach is an author and maker who lives, works and eats in Accord, NY. Feedback to email@example.com.