BSIP via Getty Images Nonenal, a chemical compound that people develop as they age, is the culprit behind the smell.

Nonenal, a chemical compound that people develop as they age, is the culprit behind the smell, which has been described by the National Institutes of Health as an “unpleasant greasy and grassy odor.” It is often hard to self-detect, but will linger on fabric such as shirt collars and pillow cases. Nonenal odors thrive in confined environments, according to Aging Care.

Japanese culture, which holds its elderly population in high regard, even has a special word for “old people smell:” Kareishu. Nonetheless, Japanese companies have set out to rid the world of it.

Given that the companies leading the charge against Nonenal also stand to gain financially from it, it would be easy to write this off as just an innovative way to capitalize on people’s insecurities.

Truth is, “old people smell” ― while arguably not the nicest or most respectful way to talk about our elders ― is a real thing.

Here’s how body odor works for older people: Hormonal imbalances that occur during aging often result in more lipid acid, a fatty acid produced in our skin. And as skin matures, its natural antioxidant protection decreases, resulting in greater oxidation of lipid acid. When lipid acid is oxidized, the chemical compound Nonenal is produced.

Given that it’s real, is it something we need to address beyond scolding the young that “old people smell” is an offensive descriptor? Maybe not. A 2012 Swedish study found that seniors’ body odors were the least offensive of any age group.

That said, they may forebear other changes that do warrant attention. For example, many women experience body odor changes during menopause. Hot flashes and night sweat during menopause cause excessive perspiration and increased fatty acids, resulting in Nonenal. And that old bugaboo, stress, can exacerbate the production of Nonenal in both women and men.