Although fitness fanatics may have already known this, a recent study confirmed it: Polyester gym clothes enhance the scent of body odor more than cotton clothing. A team of Belgian researchers collected the sweat-soaked shirts of 26 athletes for some odor-analyzing before coming to this conclusion. However, the reason for cotton’s odor-busting skills is likely not what you imagined.

For the study, 26 volunteers, half of which wore polyester and half of which wore cotton, handed in their sweaty gym wear to scientists after an intense hour-long spin class, the NY Daily News reported. As you may have guessed, the scientists found the cotton t-shirts to smell slightly more pleasant than polyester garments, and first author on the study, Chris Callewaert of Ghent University in Belgium, explained why.

Although body odor is influenced by our hygiene, genetics, food, and the environment, the most influential aspect to what determines an individual’s body odor is bacteria. Odor-causing bacteria produced in our armpits, called micrococci, are able to thrive in larger quantities in polyester than in cotton, thus increasing the scent potential of the sweat. "Freshly secreted sweat has little odor because the long-chain fatty acids the axillaries secrete are too big to be volatile," Callewaert said. "Bacteria break these, as well as hormones and sulfur compounds, down to waftable sized, odoriferous molecules.”

Callewaert did add that although these odors may be unpleasant to others, they are completely normal, despite the effect that bad body odor can have on an individual’s social interaction. "BO is taboo, and its prevalence is greatly underestimated," he said. "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." These individuals have an overabundance of this “bad bacteria” due to a genetic potential, and this causes them to have a pungent smell regardless of how many times they may wash per day, Callewaert explained in on his YouTube channel TEDx Talks.

The researcher’s eventual goal is to eliminate the concern of body odor once and for all by replacing modern day deodorant with a chemistry-based alternative. Check out his website,, where Callewaert describes his research on counteracting “malodor generating bacteria in the armpts, clothes, [and] washing machines.” Until this super-deodorant is created Callewaert recommends we stick to cotton for our workout sessions.

Source: Callewaert C, De Maeseneire E, Kerckhof FM, et al. Microbial Odor Profile Of Polyester And Cotton Clothes After A Fitness Session. Applied and Environmental Microbiology. 2014.