Sweat is a mysterious thing.If you ran a couple of miles, wiped a touch of sweat from your forehead and held it to your nose, it wouldn’t smell. But what if you swipe your underarm and sniff? You stink. Extraordinarily, sweat itself doesn’t generally smell, at least not at first. So what does?
Even though the skin is not a component of sweat, what’s on it is also responsible for why you smell. In fact, there are 100 different volatile organic compounds on human skin, the largest organ on your body. One is benzothiazole, a smelly sulfur compound often used as a food additive. Scent scientists suspect that the concentration of these compounds varies with age.
Beyond the science of stink, eventually all those VOCs emanating from skin may signal health problems, if we develop the technology to detect them.
Bacteria truly go wild for foot sweat. Foot smell is frequently sharp, and shoes and socks give a delectable feeding ground to microscopic organisms that chow down on the sweat and waste matter discharged by the sole of the foot.
Scientists who study foot scent have discovered high levels of fatty acids in those with very smelly feet. The fundamental guilty party is by all accounts isovaleric acid, a short-chain unsaturated fat generally found in cheddar and beer. Sweat likewise contains propionic corrosive, another unsaturated fat that have stronger odor than vinegar.
For years and years, scientists have been studying why armpits are so vile. Along with all the bacteria and apocrine, eccrine and hair glands present under the crook of your arm, underarm sweat contains androstenone and other steroids. Androstenone is found in both males and females, and, for what it’s worth, boar saliva.
In humans, androstenone produces a rather unpleasant musky, woody smell. It’s also associated with the scent of urine. On the flip side, some folks perceive its scent as sweet and floral, and still other sniffers can’t smell it at all.
Why is it that some people smell like cleaning liquid after a heavy workout? That’s because their bodies are processing protein.
When, say, a weightlifter eats a protein-rich diet and exercises afterward, that person’s body may turn the proteins into energy. How? By ditching the nitrogen and transforming the remaining molecule into glucose, which the body uses for fuel. The nitrogen, in turn, may then combine to form ammonia, which we can expel as urea through urine. We can also sweat it out.
If your sweat stinks of ammonia, you may want to try to up your carb intake and, of course, see your doctor.
Humans have two main types of sweat glands. Eccrine glands cover most of the body and produce a salty, watery sweat. You likely have between 2 and 5 million of them. Apocrine glands are found typically under our armpits and groin. They grow and begin to function after puberty. Apocrine glands secrete a milky type of sweat, the main ingredient of which is water, along with proteins, lipids, fatty acids, cholesterol and iron-containing salts.
When all that sweat encounters the bacteria brimming on your skin, odors start to rise. The bacteria, such as Staphylococcus epidermis and S. aureus, break down the sweat and generate smelly byproducts. So, in a sense, we cheated a bit on this one. The bacteria don’t pose the problem, the byproducts do. We’ll get to a few of them, too.