The textiles that make up our clothing protect our bodies against external factors. However these textiles are not sterile and can be a place where high bacterial counts live as sweat and as bacteria that is transmitted from the skin. This can cause unpleasant odours. The main culprit bacteria are known as micrococci because they are able to transform and break down long-chain fatty acids – freshly secreted sweat with little odour, hormones, sulfur compounds and amino acids into smaller, volatile and more waftable sized compounds that typically have a bad odour. Corynebacteria are the main cause of bad odours in the armpits but fail to actually grow on textiles according to first author of the study Chris Callewaert.

The study conducted in the journal, Applied and Environmental Microbiology, investigated this microbial growth and odour development in cotton and synthetic fabrics after the wearers underwent an intense workout session. The study collected t-shirts of both polyester and cotton fabrics from 26 healthy individuals after a spinning session and was incubated for 28 days before even being analyzed. The use of a trained odour panel was used to determine the differences between these two fabrics.

What it found was that the micrococci bacteria were able to grow better on polyester than cotton due to the suspected nature of its surface. It was found solely on the synthetic shirts. Polyester t-shirts then had a significantly less pleasant and more intense odour than the cotton t-shirts.

Unpleasant body odour is a big problem with many people suffering from it. By wearing cotton clothes when working out will really help reduce the problem somewhat but Callewaert wants to take it further to solve the problem of body odour entirely.

“Body odour 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.”

He also advises that if people suffer from very smelly armpits they should avoid overusing antiperspirants as they encourage enrichment of the corynebacteria growth.