Researchers say that regular use of antiperspirants kills off beneficial bacteria that are thought to help protect against infection and disease.
The scientists, from North Carolina Central University, found that alcohol and other chemicals in these products radically altered the populations of single-celled organisms that live in our armpits.
Lead researcher, Dr Julie Horvath, said: “We wanted to understand what effect antiperspirant and deodorant have on the microbial life that lives on our bodies, and how our daily habits influence the life that lives on us.
“Ultimately, we want to know if any changes in our microbial ecosystem are good or bad, but first we have to know what the landscape looks like and how our daily habits change it.”
The scientists tracked 27 people who usually used antiperspirants or deodorants, over an eight-day period. On the first day all of the subjects carried on with their normal routine. They then avoided using the products for five days, before all of them used antiperspirant on the last two days.
When scientists analyzed underarm swabs from those who generally did not use deodorants or antiperspirant, they found high quantities of Corynebacteria, which contribute to body odour — but are also thought to help as a defence against disease. The armpits of regular antiperspirant and deodorant users were dominated by organisms from the Staphylococcus family, described as a “grab-bag of opportunistic bacteria”
The researchers say they don’t know if antiperspirant and deodorant use is harmful to overall health, but called their study findings “important”.