Body odor

Body odor
Classification and external resources
ICD-10	L75.0
ICD-9	705.89
DiseasesDB	28886
eMedicine	derm/597

Body odor or body odour, sometimes colloquially abbreviated as B.O., is the smell of bacteria growing on the body. The bacteria multiply rapidly in the presence of sweat, but sweat itself is almost completely odorless to humans.

The condition can be known medically as bromhidrosis, apocrine bromhidrosis, bromidrosis, osmidrosis, ozochrotia, fetid sweat, body smell or malodorous sweating.^{[1]:779[2]:707}

Specificity

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

Propionic acid (propanoic acid) is present in many sweat samples. This acid is a breakdown product of some amino acids by propionibacteria, which thrive in the ducts of adolescent and adult sebaceous glands. Because propionic acid is chemically similar to acetic acid with similar characteristics including odor, body odors may be identified as having a vinegar-like smell by certain people.^{[citation needed]} Isovaleric acid (3-methyl butanoic acid) is the other source of body odor as a result of actions of the bacteria Staphylococcus epidermidis,^[3] which is also present in several strong cheese types.

Genetics

Body odor is largely influenced by 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 have shown that potential sexual partners tend to be perceived more attractive if their MHC composition is substantially different.^{[citation needed]} This behavior pattern promotes variability of the immune system of individuals in the population, thus making the population more robust against new diseases.

One study suggests that body odor is genetically determined by a gene that also codes the type of earwax one has.^[4][5] East Asians (those of Chinese, Japanese, Korean, and Vietnamese descent) have the type of sweat glands that even after hitting puberty still don't produce the chemicals found in the perspiration of other ancestral groups. 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.

Alterations

Body odor may be reduced or prevented or even aggravated by using deodorants, antiperspirants, disinfectants (e.g., triclosan), special soaps or foams with antiseptic plant extracts such as ribwort and liquorice, chlorophyllin ointments and sprays topically, and chlorophyllin supplements internally.^[6] Although body odor is commonly associated with hygiene practices, its presentation can be affected by changes in diet as well as the other factors discussed above.^[7]

Causes

Body odor is caused by the actions of skin flora, including members of Corynebacterium, which manufacture enzymes called lipases that break down the lipids in sweat to create smaller molecules like butyric acid. These smaller molecules smell, and give body odor its characteristic aroma.^[8]

See also

Butyric acid Drug resistance Foot odor Halitosis (bad breath)            Human flora

Olfactophilia Pheromone Sweat gland Trimethylaminuria Underarm liners

References

Notes

1. ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0721629210.
2. ^ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0071380760.
3. ^ Ara K, Hama M, Akiba S et al. (2006). "Foot odor due to microbial metabolism and its control". Can. J. Microbiol. 52 (4): 357–64. doi:10.1139/w05-130. PMID 16699586. 
4. ^ Wade, Nicholas (2006-01-29). "Japanese Scientists Identify Ear Wax Gene". New York Times. http://www.nytimes.com/2006/01/29/science/29cnd-ear.html?ex=1296190800&en=7f6c667589328421&ei=5088&partner=rssnyt&emc=rss. Retrieved 2007-07-05. 
5. ^ Yoshiura K, Kinoshita A, Ishida T et al. (2006). "A SNP in the ABCC11 gene is the determinant of human earwax type". Nat. Genet. 38 (3): 324–30. doi:10.1038/ng1733. PMID 16444273. http://www.nature.com/ng/journal/v38/n3/abs/ng1733.html. 
6. ^ "Chlorophyll and Chlorophyllin". http://lpi.oregonstate.edu/infocenter/phytochemicals/chlorophylls/. Retrieved 2010-01-29. 
7. ^ "Learn How to Fight Body Odor". http://www.mdhealthnetwork.org/BodyOder.html. Retrieved 2007-07-05. 
8. ^ Buckman, Dr. Robert (2003). Human Wildlife: The Life That Lives On Us. Baltimore: The Johns Hopkins University Press. pp. 93-4

External links

• Flores G (2004). "Immunity, smell linked". The Scientist 5 (1). http://www.the-scientist.com/news/20041105/02. 
• Male sweat boosts women's hormone levels -- from UC Berkeley, February 2007
• "Odors and metabolic disease" from Miami Children's Brain Institute
• Causes of body odor