Scientists have discovered exactly what causes body odour

Scientists have traced the source of body odour to a particular enzyme, which lives in the armpit (Photo: Shutterstock)

Scientists have traced the source of body odour to a particular enzyme, which lives in the armpit.

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Researchers at the University of York traced the mechanism behind underarm odour to a certain enzyme, and believe the discovery could help make more effective antiperspirants and deodorants.

The science behind BO

The study, which was published in Scientific Reports, found out how the odour from armpits is produced.

“We’ve discovered how the odour is produced. What we really want to understand now is why,” said Professor Gavin Thomas, a senior microbiologist on the team.

Humans do not produce the most pungent constituents of body odour (BO) - known as thioalcohols - directly. The team in York previously discovered that most microbes on the skin cannot make thioalcohols.

However, further tests revealed that Staphylococcus hominis was a major contributor, which produces fumes then released by sweat glands in the armpit.

The scientists explored Staphylococcus hominis in order to learn how it made thioalcohols, discovering an enzyme that converts Cys-Gly-3M3SH, released by apocrine glands, into the pungent thioalcohol, 3M3SH.

Mr Thomas said, “The bacteria take up the molecule and eat some of it, but the rest they spit out, and that is one of the key molecules we recognise as body odour.”

In order to prove that the enzyme was the culprit behind the smell of body odour, the scientists then transferred it into Staphylococcus aureus, which is a common relative that normally has no role in body odour. This then began to emanate bad smells.

“Our noses are extremely good at detecting these thioalcohols at extremely low thresholds, which is why they are really important for body odour. They have a very characteristic cheesy, oniony smell that you would recognise. They are incredibly pungent,” adds Mr Thomas.

Findings could improve antiperspirants and deodorants

The research, which is in a collaboration with Unilever, now raises new opportunities for deodorants that target just the most active microbes that produce body odour.

Mr Thomas explains, “If you can have a more targeted approach that selectively knocks down Staphylococcus hominis, it could be longer lasting.”

Co-first author, Dr Michelle Rudden, from the group of Prof Gavin Thomas in the University of York's Department of Biology, said, "Solving the structure of this 'BO enzyme' has allowed us to pinpoint the molecular step inside certain bacteria that makes the odour molecules.

“This is a key advancement in understanding how body odour works, and will enable the development of targeted inhibitors that stop BO production at source without disrupting the armpit microbiome."