How Good Are Deodorants and Antiperspirants for Our Skin Microbiome

Using antiperspirant and deodorant completely rearranges the microbial ecosystem of your skin – what’s living on us and in what amounts.  (Image:   antiperspirantbottles via  flickr / CC BY 2.0 )
Using antiperspirant and deodorant completely rearranges the microbial ecosystem of your skin – what’s living on us and in what amounts. (Image: antiperspirantbottles via flickr / CC BY 2.0 )

“Like the gut or the mouth, the human skin is covered with life. The precise composition of the skin biome influences its effectiveness as a defensive layer against pathogens, and contributes to bodily odors,” researchers wrote in a new study.

This has been known since the 1950s; however the extent to which human behaviors influence the composition of skin microbes is less known.

The study suggests that while antiperspirant may keep you dry, it also disrupts the bacterial “community” that resides in your armpits.

Julie Horvath, head of the genomics and microbiology research laboratory at the NC Museum of Natural Sciences, an associate research professor at NC Central, and corresponding author of a paper describing the work published in the journal, PeerJ, said in a statement:

Standard deodorants are intended to kill off the microbes that cause body odor, and can include ethanol or other antimicrobials. This, ironically, appears to lead to an increase in microbial activity.

Antiperspirants, however, work by reducing the amount of sweat, which impacts on the moist environments preferred by microbes. This is potentially altering the entire evolutionary process of the natural bacteria.

Rob Dunn, a professor of applied ecology at NC State and co-author of the paper, said:

The experiment consisted of 17 participants, and were monitored for eight days. Five went without deodorant or antiperspirant, while five regularly used deodorant, and the remaining seven regularly used antiperspirant.

All participants had swabs taken of their armpits between 11 a.m. and 1 p.m. The samples were then cultured to determine the abundance of microbial organisms growing on each participant, and how that differed day to day.

Horvath said:

According to NC State University:

“The researchers also did genetic sequencing on all of the samples from days three and six, to determine how antiperspirant and deodorant might affect the microbial biodiversity — the composition and variety of types of bacteria — over time.

“They found that, among study participants who hadn’t worn deodorant or antiperspirant, 62 percent of the microbes they found were Corynebacteria, followed by various Staphylococcaceae bacteria (21 percent), with a random assortment of other bacteria accounting for less than 10 percent.

“Corynebacteria are partially responsible for producing the bad smells we associate with body odor, but they are also thought to help us defend against pathogens. Staphylococcaceae are a diverse group of bacteria that are among the most common microbes found on human skin and, while some can pose a risk to human health, most are considered beneficial.”

However, the participants who regularly used antiperspirant had wildly different results. Sixty percent of their microbes were Staphylococcaceae, only 14 percent were Corynebacteria, and more than 20 percent were filed under “other” — meaning they were a grab bag of opportunistic bacteria.

Horvath noted:

The findings highlight how human behavior can have a profound impact on the evolution of microbial organisms.

“Over evolutionary time, we would expect our microbes to co-evolve with us,” Horvath says. “But we appear to have altered that process considerably through our habits, from bathing to taking steps to change the way we look or smell.”

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