A study conducted in Belgium confirms what your workouts may already have taught you: that polyester attracts and captures odour-causing bacteria more than cotton, making polyester clothes smell worse than cotton clothing after exercise.
First author Chris Callewaert of Ghent University in Belgium asked 26 athletes to hand in their shirts after an intensive hour-long spinning class. Half of the shirts were cotton and half were polyester.
"Freshly secreted sweat has little odour, because the long-chain fatty acids the axillaries secrete are too big to be volatile," says Callewaert. "Bacteria break these, as well as hormones and sulfur compounds, down to waftable sized, odoriferous molecules."
For many, even the first part of Callewaert's statement may seem confusing, so we're breaking down his findings into a guide to basic body odour-causing bacteria:
The culprit is micrococci, according to Callewaert, and these take up residence in polyester in significantly greater quantities than cotton.
Odour-causing corynebacteria are produced in the armpits and Callewaert says they fail to grow on all textiles, even polyester. He cautions against over-using antiperspirant because this can actually encourage their conglomeration on the skin.
Staphylococci inhabit both axillary skin and adjacent textiles, although the odour they create is normal and non-malodorous, according to Callewaert.
"BO is taboo, and its prevalence is greatly underestimated," he says. "There is little these people can do to help themselves. Some of them are too psychologically distressed to talk to strangers, or even to leave the house, afraid of what people might think of their smell."
Callewaert hopes to one day wipe out body odour for good by transplanting microbes from sweeter-smelling relatives of corynebacteria and micrococci and he says early results are promising. For more information, see his website: drarmpit.com.
A trend of adding antibacterial compounds into textiles for athletic wear was harshly criticized in a 2012 study by the Swedish
Chemical Agency due to the speed at which silver, triclosan and triclocarban parted, sometimes after just three washings. Triclosan and triclocarban, they noted, could be harmful to human health and the environment.
Sportswear companies solved the problem by adding silver nanoparticles which, according to researchers at Empa Swiss Federal Laboratories for Materials Science and Technology, whose study on the subject was published in June, are less likely to wash out of the textiles.
The use of silver nanoparticles was criticized in a Danish study published in February that found they could penetrate cell membranes, creating free radicals, an abundance of which can lead to serious diseases such as cancer and Alzheimer's.
By recommending cotton, Callewaert may be onto something. His study was published in the journal Applied and Environmental Microbiology.