WASHINGTON For women, apparently there's nothing like the smell of a man's sweat.
Researchers at the University of California at Berkeley said women who sniffed a chemical found in male sweat experienced elevated levels of an important hormone, along with higher sexual arousal, faster heart rate and other effects.
They said the study, published this week in the Journal of Neuroscience, represents the first direct evidence that people secrete a scent that influences the hormones of the opposite sex.
The study focused on androstadienone, considered a male chemical signal. Previous research had established that a whiff of it affected women's mood, sexual and physiological arousal and brain activation. Its impact on hormones was less clear.
A derivative of testosterone, it is found in male sweat as well as in saliva and semen. It smells somewhat musky.
"It really tells us that a lot of things can be triggered by smelling sweat," Claire Wyart, who led the study, said in an interview on Wednesday.
The researchers measured levels of the hormone cortisol in the saliva of 48 female undergraduates at Berkeley, average age of about 21, after the women took 20 sniffs from a jar of androstadienone. Cortisol is secreted by the body to help maintain proper arousal and sense of well-being, respond to stress and other functions.
Cortisol levels in the women who smelled androstadienone shot up within roughly 15 minutes and stayed elevated for up to an hour. Consistent with previous research, the women also reported improved mood, higher sexual arousal, and had increased blood pressure, heart rate and breathing.
For comparison's sake, women also smelled baking yeast, which did not trigger the same effects.
This was the first time that smelling a specific chemical secreted by people was shown to affect hormonal levels, the researchers said. The women had no skin contact with androstadienone.
The researchers used only heterosexual women in the study out of concern that homosexual women may respond differently to this male chemical.
Wyart said while this marked the first time a specific component of male sweat was demonstrated to influence women's hormones, other components of sweat may do similar things.
The study did not determine whether the increase in cortisol levels triggered mood or arousal changes or whether those changes themselves caused the cortisol elevation.
The researchers also said their findings suggest a better way to stimulate cortisol levels in patients who need it, such as those with Addison's disease. Instead of giving cortisol in pill form, which has side effects such as peptic ulcers, osteoporosis, weight gain and mood disorders, smelling a chemical like androstadienone could be used to affect cortisol levels, they suggested.