Why does sweat smell?

Why does sweat smell?

We all know the feeling when we have been busy or physically active - the feeling of smelling of sweat and longing for a shower in order to become odorless. But why is there a difference in how much our sweat smells?

What is sweat?

Sweat is the body's natural temperature regulator. This means that if the body temperature rises, the production of sweat will increase in order to keep the temperature down. You can experience this function when you are in the gym, running or generally busy. However, sweat production may also increase due to your emotional state, e.g. if you are afraid or stressed.


Why does sweat smell?

Sweat is in itself odorless, but when the sweat travels from the sweat gland and onto the skin, where it is mixed with the bacteria of the skin, this can create obnoxious smells.

There are various reasons as to why sweat smells, for example: 

  • Hereditary conditions:Your sweat will most likely smell the same as your other family members. A Swiss study conducted on 12 pairs of twins showed that the pattern and amount of carboxylic acid (the chemicals that occur most in body odor) were up to 10 times more similar in identical pairs of twins than if they were compared to people that they were not related to. 
  • Bacteria:All people have an individual blend of bacteria on the skin of the armpit. One study has shown that there are especially three types of bacteria that can cause your sweat to smell:
    • Corynebacterium (creates a smell of goat)
    • Staphylococcus (creates an smell of onion)
    • Anaerococcus (creates a smell of caraway)

If you have all three bacteria on your skin, your sweat will smell distinctly while a smaller amount of these bacteria will create a more neutral smell of sweat. The study also showed that women have more Staphylococcus bacteria (onion odor), while men have more Corynebacterium bacteria (goat odor). 

  • Types of sweat glands:The type of sweat gland also determines how much sweat smells. Sweat glands that are located in the armpits and crotch also secrete lactic acid and urea. These substances help nourish the bacteria that are on the skin which increases the pungent odor. The sweat glands on the rest of the body only secrete sweat that contain salts. The bacteria cannot live off these salts, thus, this kind of sweat does not smell.


What can be done to reduce the smell of sweat?

There are a number of things you can do on your own to avoid the smell of sweat, including:

  • Bathe: Preferably daily, and use soap to limit the amount of bacteria on the skin
  • Avoid synthetic clothing: Clothes made of cotton smell less after a workout than clothes made of polyester. This is because bacteria grow better on polyester than on cotton
  • Antiperspirants: Reduce sweat production and can be used in the armpits and on hands and feet. Read and follow the directions for use for the particular product
  • Change shoes frequently: If you experience issues with sweaty feet, avoid using the same shoes for two consecutive days
  • Food: Certain foods can enhance the smell of sweat, so avoid or cut down on foods such as caffeinated beverages, onions and garlic
  • Stress: If your sweat production is stress-dependent, it may help to do meditation, yoga or breathing exercises

1. https://videnskab.dk/krop-sundhed/lugten-af-din-armsved-er-arvelig
2. https://illvid.dk/mennesket/kroppen/bakterier-giver-din-sved-en-lugt-af-ge…
3. https://www.ncbi.nlm.nih.gov/pubmed/23950955
4. https://videnskab.dk/kort-nyt/svedlugt-bomuld-stinker-mindre-end-polyester…
5. https://www.sundhed.dk/borger/patienthaandbogen/hud/sygdomme/svedgener/sve…

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