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January 10, 2019

BehindTheMedspeak: Old-people smell

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Long story short: it exists, and results from high levels of 2-Nonenol (above) produced by skin.

• Contrary to popular supposition, the so-called "old-person smell" is rated as less intense and less unpleasant than body odors of middle-aged and young individuals.

• In humans, a unique "old person smell' is recognized across cultures. This phenomenon is so acknowledged in Japan that there is a special word to describe this odor, kareishūh.

It was first characterized in a paper published in 2001, whose abstract is below.

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Human body odor consists of various kinds of odor components. Here, we have investigated the changes in body odor associated with aging. The body odor of subjects between the ages of 26 and 75 was analyzed by headspace gas chromatography/mass spectrometry. 2-Nonenal, an unsaturated aldehyde with an unpleasant greasy and grassy odor, was detected only in older subjects (40 y or older). Furthermore, analysis of skin surface lipids revealed that ω7 unsaturated fatty acids and lipid peroxides also increased with aging and that there were positive correlations between the amount of 2-nonenal in body odor and the amount of ω7 unsaturated fatty acids or lipid peroxides in skin surface lipids. 2-Nonenal was generated only when ω7 unsaturated fatty acids were degraded by degradation tests in which some main components of skin surface lipids were oxidatively decomposed using lipid peroxides as initiator of an oxidative chain reaction. The results indicate that 2-nonenal is generated by the oxidative degradation of ω7 unsaturated fatty acids, and suggest that 2-nonenal may be involved in the age-related change of body odor.

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A study published in the British Journal of Dermatology in 2008 confirmed the earlier findings; the conclusions of that paper are below.

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The natural variation in nonaxillary skin odorants described in this study provides a baseline of compounds we have identified from both endogenous and exogenous sources. Although complex, the profiles of volatile constituents suggest that the two body locations share a considerable number of compounds, but both quantitative and qualitative differences are present. In addition, quantitative changes due to ageing are also present. These data may provide future investigators of skin VOCs with a baseline against which any abnormalities can be viewed in searching for biomarkers of skin diseases.

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Finally, an exhaustive study published in 2012, titled "The Smell of Age: Perception and Discrimination of Body Odors of Different Ages," concluded that "Humans are able to discriminate age based on body odor alone, and this effect is mediated mainly by body odors emitted by individuals of old age."

January 10, 2019 at 02:01 PM | Permalink


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