Body odor

Bromhidrosis or body odor (also called bromidrosis, osmidrosis and ozochrotia) is the smell of bacteria growing on the body. These bacteria multiply considerably in the presence of sweat, but sweat itself is almost totally odorless. Body odor is associated with the hair, feet, groin (upper medial thigh), anus, skin in general, armpits, genitals, pubic hair, and mouth.

Specificity
Body odor is specific to the individual, and can be used to identify people, though this is more often done by dogs than by humans. An individual's body odor is also influenced by diet, gender, genetics, health, medication, and mood.

Genetics
Body odor is largely influenced by the major histocompatibility complex (MHC) molecules. These are genetically determined and play an important role in immunity of the organism. The vomeronasal organ contains cells sensitive to MHC molecules in a genotype-specific way. Experiments on animals and volunteers shown the potential sexual partners tend to be perceived more attractive if their MHC composition is substantially different. This behavior pattern promotes variability of the immune system of individuals in the population, thus making the population more robust against new diseases.

A recent study suggests that body odor is genetically determined by a gene that also codes the type of earwax one has. East Asians evidently have a greater chance of having the 'dry' earwax type and reduced axial sweating and odor. This may be due to adaptation to colder climates.

Treatment
Although body odor is commonly associated with hygiene, its presentation can be affected by changes in diet. The use of anti-bacterial soap while bathing is recommended.