Wearing Deodorant Fundamentally Alters the Bacteria On Your Body

What’s crawling around in your armpits? One scientist wants to know.

Julie Horvath, an evolutionary genomicist at North Carolina Central University, studied 17 citizen-scientists’ armpits to assess their microbial makeup. The participants were divided into three categories: people who wear antiperspirant, people who wear deodorant, and people who don’t wear any underarm product at all. Those participants then went through a series of trials to uncover the effects of not wearing deodorant or antiperspirant.

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Your daily habits influence what life forms live on you.

What they found was that antiperspirants generally did a better job of killing off microbes. More surprisingly, though, they discovered that the microbial contents of participants’ armpits were dramatically different from one another even just a few days after they quit using their respective products. (And that’s even after some deodorant user’s underarms were more bacteria-rich than other participants’ “naked” armpits to begin with.)

In other words, when deodorant- and antiperspirant-wearing participants stopped using their product, their underarm ecosystem didn’t even come close to matching that of an initially product-free armpit. Their results were published in the journal PeerJ.

It may not sound like this finding matters much, but scientists are genuinely intrigued by the creatures living under your arms.

Here’s Erin Blakemore, reporting for the Washington Post:

“I’m excited about armpits,” admits Horvath. In humans and apes, armpits (or, to get technical about it, the much less stinky-sounding axilla) are a real hotspot of evolutionary potential. Since they’re shielded from the elements, they’re a place where microbes can freely propagate. And, conveniently, they’re home to the glands that produce the most body odor, which can affect how animals mate and pass on genetic material.

In addition, Horvath’s research could help us better understand disease, antibiotic resistance, and even evolution. Eventually, she and her colleagues want to study the microbes found in earwax to see if they can discern similar differences between groups of people.