Short answer: foot odor is largely a microbial chemistry problem. Feet have many sweat glands, and shoes can trap heat and moisture. Skin bacteria then metabolize components of sweat and skin, producing volatile compounds that smell strong.
One well-studied odor molecule: isovaleric acid
A microbiology study found that Staphylococcus epidermidis, a normal resident of human skin, can produce isovaleric acid by breaking down leucine in sweat. The researchers also associated Bacillus subtilis with stronger foot odor in their samples.
That is more precise than saying feet “smell like corn chips because of one magic bacterium.” Different people, shoes, moisture levels and microbial communities can produce different odor profiles.
When smell is not just smell
Persistent odor by itself is common, but pain, cracking, intense itching, drainage or a spreading rash can indicate a skin problem that deserves medical attention.
Quick follow-ups
FAQ
Is sweat itself smelly?
Fresh sweat is not usually the main source of strong foot odor; microbial metabolism produces many of the characteristic volatile compounds.
Do only dirty feet smell?
No. Warmth, moisture, footwear, sweat rate and the skin microbiome all affect odor, even with normal hygiene.
Check the evidence
Sources
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