The old smell isn't due to poor hygiene (and you'll be surprised to know what causes it)

The so-called "old smell," a phenomenon known in Japan as kareishu, has been misunderstood for decades and often unfairly linked to poor personal hygiene. However, science has clarified that this scent is a completely natural biological process.

According to studies published in the Journal of Investigative Dermatology , as we age, our skin begins to produce a molecule called 2-nonenal, an aldehyde that emits an oily, slightly rancid odor. This substance is formed by the oxidation of unsaturated fatty acids—especially omega-7 fatty acids—and begins to accumulate in the body starting at age 40, when the body's natural antioxidant levels begin to decline.

The curious thing is that 2-nonenal is insoluble in water, so it is not completely eliminated when showering, and can remain impregnated in clothing or bedding, giving rise to that persistent and recognizable aroma in older adults.

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A scent of time: why the body changes its smell as we age

Far from being a sign of neglect or illness, this odor responds to hormonal and metabolic changes associated with aging. The research, which analyzed skin samples from people between 26 and 75 years old, identified the presence of the compound 2-nonenal, an aldehyde with an oily, herbaceous odor, which begins to develop more intensely after the age of 40. In fact, even young people can begin to develop it earlier if their diet is low in antioxidants or if they suffer significant hormonal changes. It is a natural manifestation of the life cycle, not a lapse in hygiene. Nonenal is a compound produced by the oxidation of omega-7 unsaturated fatty acids, a process that intensifies with age due to the reduction of natural antioxidants in the body.

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Hormonal changes are also present

Researchers also found a correlation between increased lipid peroxides in the skin and the production of 2-nonenal, confirming that aging and hormonal changes are directly related to this phenomenon.

These findings scientifically explain why many older adults develop a distinct body odor and underscore that it is a natural process of the body, not a result of a lack of personal care.

However, there are effective strategies to neutralize or minimize this odor, such as eating a diet rich in antioxidants, maintaining adequate hydration, exercising, and using specific products such as mild soaps, natural deodorants, and breathable clothing.

Additionally, ingredients such as baking soda, apple cider vinegar, and aloe vera are natural allies that help keep skin free of bacteria and odors without harming it.