A pungent blend of onions, cheese, and cat urine. Most of us don’t need more than one whiff to identify that generally unpleasant, the characteristic smell we call body odor. It is a universal human experience. So what is this odor, exactly? Where does it come from? And what can we do anything about it?
In order to produce this familiar scent, You just need two things your armpit’s own secretions and the bacteria that feed on them. Most people associate body odor with sweat.
The amount of odor you produce—and the power of its stench—is actually based in-part by your genetics, which helps determine what types of molecules your body produces, and in what quantity. And your body is truly a b.o. wonderland: different regions of the body produce their own strange molecular secretions and play host to different sorts of microbes.
The human body has two types of sweat glands: eccrine and apocrine. Eccrine glands are present all over your skin and secrete mainly water. Their purpose is to keep your body cool when you’re exposed to heat or enduring intense exercise.
Apocrine glands, on the other hand, develop at puberty in your armpits and a few other places on your body, these secretions are usually odorless and they don’t really do much to cool you down. Instead, they release proteins and fats. Bacteria that live on the outside of your armpits feed on the secreted fats, allowing them to thrive. They also disrupt the outer shell of the proteins that are secreted, releasing the odor.
When the bacteria feed on the proteins and fats in apocrine sweat, they turn the odorless compounds into new ones that can smell very unpleasant. Some of the worst offenders may be sulfur-containing chemicals, those give body odor its oniony aroma.
Carboxylic acids are in the mix, too, adding notes of cheese. These molecules waft up from the armpit and can be sucked directly into your noses, where they’re trapped and detected by an array of specialized receptors. Those can recognize odor molecules at concentrations of less than one in a million.
So what determines how strong your body odor might be? It depends on the resident microbial populations in your armpit and the nutrients that your glands provide them with.
Bacterial composition and concentration also vary between individuals and plays a part. Even what you eat can have a small effect on how you smell. So how can we deal with body odor?
Washing the armpits with soap and water helps but won’t remove all the bacteria since many are buried in deeper layers of the skin.
The reason certain odors are worse than others is that microbes become ecologically adapted to the environments that they are in. At some point, some kind of microbe-induced smell might have served a purpose.
Eating spicy food, onions, curry, or garlic is not going to make your body produce more potentially smelly proteins. But certain foods can still make you smell worse: if pungent foods contain fat-soluble compounds that dissolve in your body fat, they’ll often get released in your sweat. So you won’t make more odor proteins.
There is a popular theory—that the sweat you produce when you are nervous is more smelly than the sweat you produce if you are trying to cool yourself down—this is actually quite true. That’s because the sweat you produce as a result of an anxious moment contains more apocrine secretions.
Deodorants, however, inhibit bacterial activity and mask odors at the same time. Antiperspirants work by forming tiny gel plugs that block sweat glands, drying out the armpits. While we continue to battle body odor, scientists are trying to understand it. We don’t know why the brain often interprets these particular odors as off-putting.
Studies in other animals have found that such odors can have physiological effects on the body that promote reproduction, which in turn helps you pass on your genes and create new humans for microbes to feast on. some researchers have proposed that secretions from the armpit could have a positive function, too, like cementing social bonds and providing a means of chemical communication. We don’t know yet if that’s the case. For now, body odor seems to be just another smelly part of the human condition.
Smell is a potent wizard————————–Hellen Keller.
The article is gleaned originally from TEDEd- What causes body odor? but with added details and more credible sources (already included in the video description). If you’re interested, you can watch the video below.