The Bacteria Behind Foot Odor

If you’ve ever taken off your shoes at the end of a long day and caught a whiff of something foul, you’ve experienced foot odor. This unpleasant smell is very common, especially when feet are confined in shoes and socks all day. But what’s actually causing that smell emanating from your feet? The main culprits are bacteria.

Your feet contain over 250,000 sweat glands, making them one of the sweatiest spots on your body. When your feet sweat, they create the perfect warm, moist environment for bacteria to thrive in. The bacteria start munching on the sweat, dead skin cells, and oils on your feet, producing pungent waste products as a result. These waste products are what give foot odor its characteristic smell.

There are two main types of bacteria responsible for foot odor: Corynebacterium and Brevibacterium. Both of these species feed on dead skin cells and fatty acids present in sweat. As they digest these substances, smelly metabolic byproducts are created and released. These include isovaleric acid and butyric acid, which produce odors resembling cheese and vomit. Acetic acid is also produced, giving feet a vinegary smell.

Corynebacterium are commonly found between the toes and in the soles of feet. This bacterium thrives in the moist, dark environment there. Meanwhile, Brevibacterium prefers drier skin and is most abundant on the tops and sides of feet. Both bacteria produce lipases, enzymes that break down fats and oils. This produces glycerol and free fatty acids that further contribute to foot odor when metabolized.

A few other microbes can play a minor role in foot odor as well. Staphylococcus epidermidis is a bacterium usually found on human skin that can cause foot odor when allowed to overgrow. Fungal species like Candida albicans may also accumulate between the toes, exacerbating odor by breaking down keratin proteins.

Certain factors make foot odor worse and allow odor-causing bacteria to proliferate:

  • Sweating heavily, especially due to exercise, heat, or stress
  • Wearing shoes and socks that hold in heat and moisture
  • Having sweaty feet naturally due to overactive sweat glands
  • Not washing feet daily
  • Walking barefoot in public showers, pools, etc
  • Having athlete’s foot or fungal infections on the feet

Luckily, foot odor can be controlled through simple foot hygiene practices:

  • Washing feet with soap and water daily
  • Drying carefully between toes after washing
  • Using antibacterial soap or disinfectant wipes on feet
  • Applying foot powder to absorb sweat and reduce moisture
  • Wearing moisture-wicking socks
  • Alternating pairs of shoes daily to let them fully dry out
  • Disinfecting shoes with sprays or UV light to kill bacteria
  • Getting fungal infections like athlete’s foot treated

Seeing a podiatrist or dermatologist may also help in stubborn cases of foot odor. They can prescribe clinical-strength antiperspirants, specialized foot soaks, topical antibiotics, and antimicrobial foot sprays proven to kill odor-causing bacteria. With consistent foot hygiene and treatment if needed, smelly feet don’t have to be a source of embarrassment. The bacteria behind foot odor can be controlled.