3 ms·

Anecdotally, sweat starts to smell after it has soaked for a bit in bodily hair. The sweat on my forehead, back and chest never smells of anything, but the swea

Anecdotally, sweat starts to smell after it has soaked for a bit in bodily hair. The sweat on my forehead, back and chest never smells of anything, but the sweat on my scalp and in my armpits does. My theory is that the smell develops from sweat reacting with (or releasing something from) perhaps the sebum.

JohnBooty 3y ago
I find that trimming armpit hair helps a lot. Wearing sleeveless shirts (when feasible, obviously) of course helps even more.
- daneel_w 3y ago
  I did the same for a while when I was young, and it definitely reduced the build-up of odour after exercise and sports. The flip side was that I lost a lot of "wicking" ability and consequently had ridiculously large wet spots under my arms and a feeling of being "slippery" or lubricated under my arms already from just light exercise.
  - JohnBooty 3y ago
    There seems to be a big debate in popular culture re: whether or not armpit hair keeps you cooler. I certainly don't think it does. Evaporative cooling works via evaporation and armpit hair seems to do the exact opposite, at least if it's trapped under clothing and not exposed to a breeze. But... you have had the opposite experience and I am sure you are not hallucinating or lying!
throwaway4aday 3y ago
that's still bacteria that causes that
- audunw 3y ago
  It’s also a lack of bacteria. Nitrifying bacteria will generally eat up the nasty smelling compounds. But most of us basically exterminate all of them whenever we wash ourselves. They might be essential to good skin health. We’d be covered with them in the environment that evolved in. But there’s not much research being done yet in that field. I experimented with it a bit myself a while ago, both «mother dirts» commercial product and making a growth medium for them myself and adding some soil. Did a blind test with my wife to see if they affected smell, and there was a very clear difference. But where I live mother dirt is not available and it’s rather expensive anyway. The experiment encouraged me to use only the mildest body soaps and a gentler washing process which anecdotally has been good for my skin. Maybe I have a healthier skin microbiome now
- daneel_w 3y ago
  It's remarkable how I manage to get none of that on my body besides on the head and under my arms, and practically none on my clothes. My sweaty t-shirts build up smell only under the arms.
- maxerickson 3y ago
  There's also different types of sweat glands. The product of apocrine glands has more odor when broken down by bacteria than eccrine gland sweat.
0x_rs 3y ago
With your anecdote you've mostly described the difference between apocrine and eccrine sweat glands, their locations, and their effect, with the former generally causing the noticeable odour from bacterial enzymes breaking their secretion. Body hair does have a significant effect in those areas, too. Some people also don't experience this, or in a very limited manner. https://www.sciencedirect.com/science/article/pii/S0022202X15346832 https://www.sciencedirect.com/science/article/pii/S0022202X1...

JohnBooty 3y ago

I find that trimming armpit hair helps a lot. Wearing sleeveless shirts (when feasible, obviously) of course helps even more.

daneel_w 3y ago
I did the same for a while when I was young, and it definitely reduced the build-up of odour after exercise and sports. The flip side was that I lost a lot of "wicking" ability and consequently had ridiculously large wet spots under my arms and a feeling of being "slippery" or lubricated under my arms already from just light exercise.
- JohnBooty 3y ago
  There seems to be a big debate in popular culture re: whether or not armpit hair keeps you cooler. I certainly don't think it does. Evaporative cooling works via evaporation and armpit hair seems to do the exact opposite, at least if it's trapped under clothing and not exposed to a breeze. But... you have had the opposite experience and I am sure you are not hallucinating or lying!

throwaway4aday 3y ago

that's still bacteria that causes that

audunw 3y ago
It’s also a lack of bacteria. Nitrifying bacteria will generally eat up the nasty smelling compounds. But most of us basically exterminate all of them whenever we wash ourselves. They might be essential to good skin health. We’d be covered with them in the environment that evolved in. But there’s not much research being done yet in that field. I experimented with it a bit myself a while ago, both «mother dirts» commercial product and making a growth medium for them myself and adding some soil. Did a blind test with my wife to see if they affected smell, and there was a very clear difference. But where I live mother dirt is not available and it’s rather expensive anyway. The experiment encouraged me to use only the mildest body soaps and a gentler washing process which anecdotally has been good for my skin. Maybe I have a healthier skin microbiome now
daneel_w 3y ago
It's remarkable how I manage to get none of that on my body besides on the head and under my arms, and practically none on my clothes. My sweaty t-shirts build up smell only under the arms.
maxerickson 3y ago
There's also different types of sweat glands. The product of apocrine glands has more odor when broken down by bacteria than eccrine gland sweat.

0x_rs 3y ago

With your anecdote you've mostly described the difference between apocrine and eccrine sweat glands, their locations, and their effect, with the former generally causing the noticeable odour from bacterial enzymes breaking their secretion. Body hair does have a significant effect in those areas, too. Some people also don't experience this, or in a very limited manner. https://www.sciencedirect.com/science/article/pii/S0022202X15346832 https://www.sciencedirect.com/science/article/pii/S0022202X1...