Biological causes and psychological reactions to foot odor

Foot odor is primarily caused by microorganisms, such as Staphylococcus epidermidis, rather than sweat itself. When sweat and skin cells accumulate in the warm, moist microclimate of a shoe, bacteria break down these components into odorous metabolic products like isovaleric acid.

Research indicates that shoe materials and environmental conditions significantly influence odor intensity. For instance, polyester can retain odorous compounds more stubbornly and promote higher microbial accumulation compared to cotton. Proper drying, foot hygiene, and ventilation are key to managing these odors.

Psychologically, the aversion to feet and their scent is linked to the brain's 'behavioral immune system.' This evolutionary mechanism triggers disgust to protect individuals from potential pathogens found in bodily fluids or decaying matter. This reflex can even cause individuals to feel disgust toward their own feet due to associations with hygiene or physical appearance.