Cotton vs Polyester: What to Wear to Reduce Body Odor
It is well known that numerous forms of bacteria thrive inside the human body. For example, it has been estimated that about five pounds of bacteria reside within the intestinal tract of a healthy adult. Unfortunately, our coexistence with microorganisms does not end there, as bacteria also flourish on every inch of the skin. These bacteria propagate in varying quantities in different areas; about 100 bacteria live within each square centimeter on one’s forearm, versus 10 million per square centimeter in the armpits, navel, groin, and spaces between the toes. These colonies have a large role in the development of body odor when an individual sweats, even though perspiration in itself is known to be sterile and not produce foul odors. New research shows that it is primarily the environment we provide for these microbe havens (in the form of clothing) that has a major impact on the development/severity of embarrassing aromas.
A novel investigation recently published in Applied and Environmental Physiology conducted by researchers of Ghent University in Belgium, has confirmed what many anecdotal reports by gym goers have already speculated; polyester clothing attracts and captures odor-causing bacteria more than cotton. This often makes polyester-based clothing smell notably worse than cotton following exercise. First author Chris Callewaert had 26 healthy participants (13 men and 13 women) hand in their shirts after an intensive hour-long spinning class. Half of the individuals wore polyester, the other half cotton. The apparel was placed in plastic bags and stored in the dark for 28 hours to simulate tossing one’s gym clothes in a musty locker after training. After the 28-hour storage period, an independent panel of odor connoisseurs judged the polyester shirts to be noticeably more malodorous than the cotton-based shirts.
As explained by Callewaert, "Freshly secreted sweat has little odor, because the long-chain fatty acids the axillaries secrete are too big to be volatile… bacteria break these, as well as hormones and sulfur compounds, down to waftable sized, odoriferous molecules." The polyester shirts had a worse scent because of a specific type of bacteria that can thrive on the fabric (but not cotton). The culprit, known as Micrococci, was found in significant quantities in the armpit regions of the shirts. The research team suspects that the malodorous microbes reside in “sweat pools” between synthetic fibers – a perfect environment for bacterial proliferation. To further explore their theory, they took various pungent species of bacteria and tried to grow them in Petri dishes coated with a number of different fabrics, including; polyester, acryl, nylon, fleece, viscose, cotton and wool.
The above results may help inform clothing manufacturers on how to create less smelly apparel. Nico Boon, microbial ecologist and coauthor for the study explains, “Many manufacturers have started adding antimicrobials, like nanosilver, to their clothes.” It is believed that such additives may be associated with elevated free radical activity and immunosuppression due to the propensity for the compounds to penetrate skin cell membranes after liberation from the clothing’s fibers after a few washes. Nico continues, “This could potentially throw off our immune systems… We should manage and control the existing microbial community, so that we steer the germs in the way that we want, instead of killing everything.”
Callewaert’s team concludes that clothing hybrids may be optimal for reducing workout odors. They suggest construction of apparel where cotton is used in the armpit areas, and synthetic fibers are used for the rest of the shirt for reduced heat accumulation and greater overall comfort. This information provides the personal trainer with advice on how to help mitigate problems associated with clients that appear to neglect hygiene, but instead have just purchased the wrong type of workout gear.