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Body odor (BO), also spelled body odour, is present in animals (including humans), and its intensity can be influenced by many factors (behavioral patterns, survival strategies). Body odor has a strong genetic basis both in animals and humans, but it can be also strongly influenced by various diseases and psychological conditions. Body odor is generally considered to be an unpleasant odor among many human cultures. == Causes == In humans, the formation of body odors is mainly caused by skin glands excretions and bacterial activity. Between the different types of skin glands, the human body odor is primarily the result of the apocrine sweat glands, which secrete the majority of chemical compounds needed for the skin flora to metabolize it into odorant substances.〔 This happens mostly in the axillary (armpit) region, although the gland can also be found in the areola, anogenital region, and around the navel. In humans the armpit regions seem more important than the genital region for body odor which may be related to human bipedalism. The genital and armpit regions also contain springy hairs which help diffuse body odors.〔 The main components of human axillary odor are unsaturated or hydroxylated branched fatty acids with E-3M2H (E-3-methyl-2-hexenoic acid) and HMHA (3-hydroxy-3-methyl-hexanoic acid), sulfanylalkanols and particularly 3M3SH (3-methyl-3-sulfanylhexan-1-ol), and the odoriferous steroids androstenone (5α-androst-16-en-3-one) and androstenol (5α-androst-16-en-3α-ol).〔 E-3M2H is bound and carried by two apocrine secretion odor-binding proteins, ASOB1 and ASOB2, to the skin surface. Body odor is influenced by the actions of the 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. ''Staphylococcus hominis'' is also known for producing thioalcohol compounds that contribute to odors.〔http://www.sciencedaily.com/releases/2015/03/150330213947.htm〕 These smaller molecules smell, and give body odor its characteristic aroma.〔Buckman, Robert (2003). Human Wildlife: The Life That Lives On Us. Baltimore: The Johns Hopkins University Press. pp. 93-4〕 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. Isovaleric acid (3-methyl butanoic acid) is the other source of body odor as a result of actions of the bacteria ''Staphylococcus epidermidis'', which is also present in several strong cheese types. Factors such as food, drink, and diseases can affect body odor.〔 An individual's body odor is also influenced by lifestyle, sex, genetics, and medication. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Body odor」の詳細全文を読む スポンサード リンク
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