Men Smell Like Cheese, Women Smell Like Onions

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Men Smell Like Cheese, Women Smell Like Onions

Body odor (BO) is not fun, either in private or social situations. If always present, it must be dealt with daily as BO is the target of endless jokes in bad taste.

But now, there is something new that can be said about this situation - and note that this post is not a joke. A research team in Switzerland recently took a close look at how human BO is processed by the olfactory system and the brain. This research analyzed armpit sweat from two dozen men and 25 women after each person had been in a sauna or ridden an exercise bike for 15 minutes. 



The sweat from women contained high levels of a sulfur compound that had no odor. The bacteria commonly found in armpits turn this compound into another one known as thiol that smells like onions. Men have only one tenth of the female amount of their odorless armpit sweat compound - a fatty acid in men. When male armpit bacteria process this fatty acid, the result is a compound that smells like cheese, although men are not able to generate the highest levels of unpleasant ‘malodor’ that can be synthesized by women.

Christian Starkenmann

The researchers found marked differences in the sweat from men and women.

"Men smell of cheese, and women of grapefruit or onion," says Christian Starkenmann of Firmenich, a company in Geneva that researches flavors and perfumes for food and cosmetics companies.


The team found that the women's armpit sweat contained relatively high levels of an odorless sulphur-containing compound - 5 milligrams per milliliter of sweat versus 0.5 milligrams in men.
When the researchers mixed this compound in the lab with bacteria commonly found in the armpit, the bugs turned it into a thiol - a previously discovered odor from armpits that is akin to onion.


"The more sulphur precursor we added, the more intense was the malodor," says Starkenmann, whose team's results appear in Chemical Senses (DOI: 10.1093/chemse/bjn076). Bacterial enzymes turn the otherwise odorless precursor into the malodor.
The men, meanwhile, had relatively high levels of an odorless fatty acid which turned into a cheesy odor when exposed to the same types of bacteria. The balance of oniony to cheesy precursors in women's sweat made it smell worse than men's as rated by independent smell assessors.


Chemicals in men's bodies can cause their female sex partners to be more fertile, have more regular menstrual cycles and milder menopause, landmark research shows. And women who have sex with men at least once a week benefit most from the chemicals, which apparently work through the sense of smell. 


"The exciting part is the effect we have on each other. Men are important to women," says Dr. Winnifred B. Cutler of Philadelphia, whose studies show for the first time that chemicals called pheromones exist in humans. Pheromones have long been known to exist in animals, as scents that attract sex partners. Cutler's new studies...show women are affected by pheromones from men and women:
*Women with unusually long or short menstrual cycles get closer-to-average cycles after regularly inhaling male essence, described as a compound of male sweat, hormones and natural body odors. "You just walk into a male locker room," Cutler says, "that's the odor."
*Women exposed to another woman's "female essence" menstruated at the same time after a few months, confirming a long-observed phenomenon that women who live together menstruate at the same time.
Cutler's other studies show women who have sex with men at least once a week have regular menstrual cycles and fewer fertility and menopause problems, apparently because of exposure to pheromones....

Many factors will influence the production of BO in both men and women: diet and supplements, soaps and trace elements in washing water, family and ethnic group genetics, local climate and the material used in clothing. Plastic clothing made from synthetic fibers such as polyester is well known to cause excessive sweating in many people.

This Swiss research could lead to new deodorants and pharmaceuticals to block the synthesis of thiol in women and the fatty acid or armpit molecular in men.
Compounds might be synthesized that prevent armpit bacteria from converting the odorless precursor molecules into compounds that smell like onions or cheese.
At the end of the day, however, all is not negative. Without any deliberate thought, a woman cooking and eating a cheeseburger or grilled cheese sandwich might notice a pleasant sensation unrelated to favorite food odors.

A ‘cheesy’ smell might call forth pleasant thoughts and feelings about a favorite man in her life.
The male armpit molecule that smells cheesy has a representative in any grilled cheese sandwich.
Men, when smelling onions, may have a similar, evocative reaction.



Who would have ever imagined that onions and cheese could be emitting human pheromone analogs?

Sources:
newscientist.com
athena.science
bennet