Why Do Old People Smell?

[Mike047]

Being old myself, I found it a bit insulting when this question was put to me some time back. There are circumstances that clearly can lead to problems, such as poor washing routines through inability to reach everywhere. Being unable to totally control natural processes that can lead to soiled clothing. Yes, we know these are problem areas, but even without these problems, there is still the question about body odour, why?

 

Scientific studies show that aging alters body chemistry, leading to a distinct scent often associated with older adults. The key culprit is a compound called 2-nonenal.

 

To explain:

•     2-Nonenal: This unsaturated aldehyde is produced as the body ages, typically starting around age 40. It has a grassy or greasy odor, often described as musty or slightly sweet.
•     Skin Lipid Changes: Aging alters the composition of skin surface lipids, especially monounsaturated fatty acids. These changes promote the formation of 2-nonenal through oxidation.
•     Lipid Peroxides: Increased oxidative stress in older skin leads to more lipid peroxides, which further contribute to the production of odorous compounds.

 

There are also other factors:

•     Reduced Sweat and Sebum Production: While younger people’s body odor is often driven by sweat and bacterial breakdown, older adults produce less sweat and sebum, shifting the odor profile toward aldehydes like 2-nonenal.
•     Other Compounds: Some studies found elevated levels of benzothiazole, dimethylsulphone, and nonanal in older individuals, suggesting a broader chemical basis beyond just 2-nonenal.

 

In Japan, I believe this phenomenon is so well recognized that it has a name: kareishuu (加齢臭), meaning “aging odor.” It’s considered a natural part of growing older, not a hygiene issue.

 

So, even though it seems like an unpleasant topic to bring up, there’s a solid biochemical basis for the phenomenon—and it’s more about molecular aging than missed showers.