There are plenty of reasons to want to change the bacteria that live on and in you. Scientists have linked a large number of these human-loving microbes to particular measures of health or illness. A certain species of bacteria might make your gut ever-slightly-so more prone to obesity. Another might give you the healthy, regular bowel movements you've been trying to create with endless fiber supplements and diet shifts. Yet another might have made you more prone to asthma as a child.
You might think that the surface of your skin, which comes in contact with countless foreign surfaces teeming with their own bacteria every day, would change with regularity. But previous research has shown that humans tend to change the bacterial makeup of the environments we encounter — we leave our microbial "fingerprints" everywhere, and even colonize hotel rooms with our preferential species within a few hours. According to a study published Thursday in the journal Cell, the microbes on our skin are surprisingly resilient over time.
Senior study authors Heidi Kong of the National Cancer Institute and Julie Segre of the National Human Genome Research Institute found that microbes showed a strong preference for particular skin types, like moist areas around the genitals, oily regions like the outer ear canal or dry areas like the palm of the hand. That wasn't a surprise — previous studies have shown that skin microbes tend to like certain terrain. If you compared your microbiome to that of a total stranger, their armpit bacteria would probably have more in common with your armpit bacteria than the microbes from the skin of your own forearm would.
The new study is small, showcasing just 12 individuals sampled at different intervals over the course of a couple years. But Kong and Segre say they found compelling evidence that microbes linger on the skin for a long time, with some species and sites showing even more resilience than others.
"The stability of a healthy individual’s skin microbial communities extending beyond 1-2 years was surprising," Segre told The Post in an email. "Despite routine skin hygiene and environmental exposures during these time periods, the composition of the skin microbial communities of an individual was relatively consistent. Some sites like the oily areas (back) were more similar over time, whereas some sites like the feet were more varied over time."
The variability of feet may be due to our clothing habits. Most humans wear a rotation of different socks and shoes, and sometimes go barefoot, which means feet spend significant time stewing in different sorts of environments. A few hours in socks, an hour sweating at the gym in different shoes, and a trip to the shower followed by a few hours padding barefoot through your house's carpet might provide more chances for bacterial colonization than a few firm handshakes and quick swipes across foreign surfaces would in hands.
"Knowing that there is relative stability in healthy skin will be important in comparing the skin microbial communities in patients as well as potential future studies that explore whether we can alter our skin microbes," Kong added.
The skin, she explained, is the body's first line of defense against infection. Kong, Segre and their colleagues want to study how particular microbes might make us sick or healthy, but they're also interested in how the overall makeup of a microbial community can increase or decrease the skin's ability to protect us from foreign invaders.
Certain individuals in the study were more or less prone to variability — even at sites like the feet — than others, suggesting that behavior or even genetics could affect how tenacious our bacterial communities are. Understanding how variation helps or hurts an individual could be important. Are you more likely to pick up a dangerous infection if your microbes are stalwart and steadfast, or does a tendency towards quick variability make you more likely to battle those dangerous bacteria quickly? Further study is needed to find the answer.
It's possible that one day scientists will decide what makes a "good" skin microbiome and what makes a "bad" one. If that day ever comes, we could theoretically try to recolonize ourselves with a better mix of bacteria and fungi. But Kong and Segre strongly advise against any DIY attempts like Zayner's.
"The microbial communities provide tremendous health benefit (resisting colonization with pathogens, tuning the immune system), so we need to recognize that most endogenous microbes on our skin, in our guts, in our mouths are healthy," Segre told The Post in an email. Research suggests that bacterial skin communities are pretty individualized. While some individuals may have a luckier lot than others, that doesn't mean swapping one microbiome out for another will have the desired effect. And trying to become sterile enough to make it happen would be nearly impossible at best and incredibly dangerous at worst.
"We should start to think of ourselves as super-organisms," Segre added. "Humans are ecosystems who are a combination of both trillions of human cells and trillions of microbes. Our health is determined by the interplay of all of the cells of our body."
In other words, try to love the skin you're in — and the microbes that live on it — because you're pretty much stuck with most of them.
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