Studies on Antiperspirants And Underarm Bacteria
That antiperspirant may keep you dry, but it might also disrupt the bacterial "community" that resides in your armpits, a new, small study suggests.
Researchers say it is not known if disruptions have any adverse effects or if they could be advantageous. These findings, which were published online in Peer J on Feb. 2, raise concerns about modern life's potential impact on the human "microbiome."
This term is used to describe the billions of microbes and bacteria that live inside the body. According to U.S. National Institutes of Health(NIH), most of the microbes that are found on our skin are beneficial or harmless.
According to the NIH, some microbes protect skin against harmful insects and can also help "educate" immune system cells living in skin.
Julie Horvath, lead researcher said that "we know that these microbes affect the immune system." It's crucial to think about what daily routines do to skin's microbiome.
According to Horvath (head of the North Carolina Museum of Natural Sciences' genomics and microbiology research laboratory), the purpose of the study wasn’t to stigmatize deodorant.
The microbial community can be affected by any type of skin product, including lotions and makeup. The NIH also mentions other factors like age, gender, and sun exposure.
Horvath was interested in the antiperspirant effects of her laboratory colleagues after they conducted an experiment together: The participants took swabs from their arms and cultured them to discover what microbes lived there.
Horvath was experiencing some public-speakingjitters. Horvath used the clinical strength antiperspirant. It turned out her armpit swab wasn't contaminated with microscopic organisms.
"I wondered, 'Where are your microbes?" She replied. "Then I thought of the clinical-strength antiperspirant."
Horvath's group recruited 17 volunteers to participate in an eight-day study. Seventeen of the women and men used antiperspirant on a regular basis, while five used deodorant. Five others used both.
All volunteers maintained their usual hygiene habits on day 1. They stopped using any underarm creams from days 2 through 6. All used antiperspirant on the last two days.
Researchers found that armpit samples from antiperspirant users showed far less bacteria than those taken from non-users. In fact, deodorant users had more bacteria.
Horvath explained that there is no reason to expect antiperspirant and non-deodorant users to be different. While deodorants have antimicrobial components that reduce odor, antiperspirants stop sweating because bacteria loves sweat .
The situation became more complex when all the participants stopped using underarm products. By the sixth day, everyone had similar levels of bacteria on their armpit swabs. However, the types and diversity of the bacteria were very different.
The most prevalent bacteria was found among people who used no products. This group is called corynebacteria and accounts for 62 per cent of all microbes detected in their armpits. Another 21 percent was made up of Staphylococcaceae.
This pattern reversed for people who normally used antiperspirant and deodorant. Staph bacteria was dominant.
Horvath explained that Corynebacteria partly contribute to body odor. However, they also defend against harmful bacteria. Although staph bacteria has a poor reputation, most strains of the organism are good. Horvath claimed that the type of staph bacteria carried by participants in her study was not determined by her team.
Pieter Dorrestein is an associate professor at University of California San Diego's Skaggs School of Pharmacy and Pharmaceutical Sciences. He found out that many personal care products, from shampoo to deodorant, to lotion and even shampoo, remain on skin after just a few days.
Dorrestein who wasn't part of this new study, said: "The data also suggested personal care and lifestyles might influence the microbes which reside on the skin surface."
He stated that he was pleased to see others take a more detailed look at one product in personal care products. He also noted some weaknesses in the research, such as the limited number of participants and the eight-day experiment chosen.
Dorrestein stated that it is not clear whether the armpit swabs of people reflect an increase in skin bacteria. Another explanation is that people who used underarm creams didn't reach as many bacteria through their barrier.
Dorrestein noted the drastic drop in bacteria swabbed on the seventh day -- the very first day all volunteers started using antiperspirant (or reusing it)
However, he stated that the study hypothesis was sound and that it would surprise him if skin care products didn't alter the skin's microbial communities.
That leaves the big question of what it means.
Horvath, study coauthor and researcher said "We have a bit of knowledge about the skin microbiome." We still have so many things to learn," Horvath said.