Foot odor

Foot odor is a type of body odor that affects the feet of humans and is characterized by a smell generally regarded as unpleasant.

Cause
Foot odor often results from wearing shoes and/or socks, especially shoes or socks with inadequate air ventilation, for many hours. Since human feet are densely covered with sweat glands (and men have larger feet and sweat more), excessive perspiration of the feet is the result. This perspiration and warmth provide ideal conditions for bacteria and/or fungi to thrive. The presence of the bacteria and/or fungi does not in and of itself cause odor; instead, as the bacteria consume dead skin cells and moisture, they in turn produce waste material. This waste material is the cause of foot odor. As physical activity increases, foot perspiration, bacterial growth, and bacterial waste production all increase, causing odor to intensify.

Since socks directly contact feet, their composition can have an impact on foot odor. Nylon is a common material used to create socks, but does not provide as much ventilation as cotton, another common sock material, so wearing nylon socks increases perspiration and therefore intensifies foot odor. Since socks absorb varying amounts of perspiration from feet, wearing shoes without socks may increase the amount of perspiration contacting feet and thereby increase bacterial activities that cause odor. People wearing nylon stockings or pantyhose may experience increased foot odor.

Odor qualities
The quality of foot odor is often reported as a thick, cheesy scent, Some describe the smell like that of Malt Vinegar, but can sometimes be ammonia-like. Brevibacteria are considered a major cause of foot odor, as they ingest dead skin on the feet, especially on the soles and between the toes, converting in the process the amino acid methionine to methanethiol which has a sulfuric aroma. The brevibacteria is also what gives cheeses such as Limburger, Bel Paese, Port du Salut, and Muenster their characteristic pungency (a sharp acrid smell).

Prevention
Among the earliest foot deodorants were aromatic herbs such as allspice, which nineteenth-century Russian soldiers would put in their boots. Some types of powders and activated charcoal insoles, such as Odor Eaters, have been developed to combat foot odor, but they are not as effective as thoroughly washing feet, choosing shoes with proper ventilation, changing socks regularly, and wearing shoes only when necessary. It is also recommended to wear socks that fit properly and are made of 100% cotton. A more natural solution would be to go barefoot though the practicality of this solution in an urban environment is questionable. If foot odor becomes offensive enough to become an issue in daily life, a physician should be consulted.

Reactions to foot odor
People grow up believing foot odor is unpleasant, making people embarrassed about how their feet smell. For this reason, in Western countries, where shoes are worn for most of the day, some people avoid removing their shoes around others. This is paradoxical, since going shoeless is one of the best ways to reduce foot perspiration. Reactions to foot odor vary across cultures; for example, there is less foot odor stigma in countries where shoes are removed upon entering the home. (For a more detailed discussion of this topic, see shoes.)

Although some people find the scent of feet unpleasant, some people find smelling feet sexually arousing. This can be part of a foot fetish or an obsession. Some people also have fetishes for the sock or shoe scent that usually accompanies warm feet (for example as part of a shoe fetish) or foot worship fetish.