Why do feet smell?

The soles of the feet are among the most densely packed areas of sweat glands on the body, with an estimated 250,000 glands across both feet. Sweat itself is almost odourless, but shoes and socks trap it in a warm, dark space where bacteria thrive. Microbes such as Staphylococcus epidermidis break down sweat and dead skin into compounds like isovaleric acid, which has a cheesy smell. Brevibacterium, another foot bacterium, is closely related to the microbes used to ripen strong cheeses such as Limburger. Washing daily, drying between the toes and alternating shoes so they dry out all reduce the smell.