Why is armpit sweat much more pungent than sweat from other areas of the body, such as back sweat?
In: Biology
Bacteria. Most of the foul odor we ascribe to sweat is actually caused by skin bacteria. Your armpit is a fairly unique environment where bacteria can remain relatively moist and protected from the outside, which is also why groin sweat can be rather pungent. Sweat on other parts of your body, say on your face, will come into contact with normal skin bacteria, but not for as long before drying off, which means that there is both less bacteria and different kinds of bacteria living on your face than your armpit. Sweat by itself is fairly odorless since its just salty water.
Okay, imagine our body has little workers who sweat to keep us cool. When these workers sweat in the armpits, there are more smelly bacteria. These bacteria mix with the sweat and make it smell stronger than sweat from other places like the back.
Apocrine sweat glands produce an odorless fluid (sweat) but begins to stink because of bacteria on skin surface
two kinds of sweat glands, eccrine and apocrine. Eccrine are most of your body’s sweat producers, while the apocrine are the majority in your armpits and perineal (taint).
Eccrine are largely responsible for cooling your body by evaporation, some excretion of water and electrolytes, and skin protection by maintaining your skin’s acid mantle (protects against bacteria colonies)
Before puberty, the apocrine sweat glands are inactive; hormonal changes in puberty cause the glands to increase in size and begin functioning. The substance secreted is thicker than eccrine sweat and provides nutrients for bacteria on the skin: the bacteria’s decomposition of sweat is what creates the acrid odor. Apocrine sweat glands are most active in times of stress and sexual excitement.
In mammals (including humans), apocrine sweat contains pheromone-like compounds to attract other organisms within their species. Study of human sweat has revealed differences between men and women in apocrine secretions.
So, daily cleaning of armpits and crotch (imo, face and hair, as well) should be mandatory, especially by adolescents.
Apocrine sweat glands start working around puberty. They are attached to hair follicles in the armpits and groin areas. They produce an oily substance rich in protein that certain bacteria on the skin’s surface consume. The waste products from the bacteria is what produces the odor.
Interestingly, a variant of the ABCC11 gene prevents the production of the proteins in the apocrine sweat glands that bacteria use to produce body odor. Only 2% of White/Caucasian people have this gene (I am one of them). This gene also causes ear wax to be white and crumbly rather than yellow/brown/red and wet or sticky.
So if you have white and crumbly ear wax, you might not even need to wear deodorant.
Body odor actually comes from bacteria, but the reason why odor is connect with sweat, is because the bacteria only produce stinky smells, when they eat organic compounds produced by certain sweat glands.
Here’s the catch: the stinky sweat glands — apocrine glands — only exist in certain areas of the body. The armpits and the genitals are the two most-important areas where apocrine glands exist, so those are the main places where bacteria turn the sweat into stink.
Back sweat isn’t produced by apocrine glands, so it doesn’t have the organic compounds that bacteria turn into stinks.
So for a few years my armpits didn’t produce any smell *as far as I could tell*. Didn’t use deodorant but sparingly for like three years, all of a sudden I started to catch a smell. I didnt usually sweat at all unless it was incredibly hot or doing very strenuous tasks, nowadays I sweat more but still not as much as some of my coworkers. What do you causes that just the lack of sweat?
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