Deodorants alter bacteria's life on your skin

Thousands of bacteria species have the potential to live on human skin, and in particular in the armpit, the researchers said, adding that anti-perspirant and deodorant can significantly reduce the influence of both the type and quantity of bacterial life found in the human armpit's "microbiome".

"Just which of these species live in any particular armpit has been hard to predict until now, but we've discovered that one of the biggest determinants of the bacteria in your armpits is your use of deodorant and/or antiperspirant," said Rob Dunn, professor at North Carolina State University in the US.

The study, published in the journal the PeerJ, focuses on the effect that anti-perspirant and deodorant have on the microbial life that lives on our bodies, and how our daily habits influence the life that lives on us, the researchers said.

To learn about the microbial impact of anti-perspirant and deodorant, the researchers recruited 17 study participants. They then launched an eight-day experiment in which all of the participants had swabs taken of their armpits.

On day one, participants followed their normal hygiene routine in regard to deodorant or anti-perspirant use. On days two through six, participants did not use any deodorant or anti-perspirant. On days seven and eight, all participants used antiperspirant.

The researchers then cultured all the samples to determine the abundance of microbial organisms growing on each participant and how that differed day to day.

The researchers found that once all participants began using anti-perspirant on days seven and eight, very few microbes were found on any of the participants, verifying that these products dramatically reduce microbial growth.