There's a Smell You Develop After 40 That You Cannot Detect on Yourself. And Almost No One Will Tell You.
It isn't sweat. It isn't poor hygiene. It's a skin compound called nonenal. In Japan, they've been washing it away for generations with something most Westerners have never heard of.
The "towel test": the first place most people finally notice it isn't their skin. It's their pillowcase or towel.
Here's an uncomfortable fact about human noses: they go blind to any smell they're exposed to constantly. Scientists call it olfactory adaptation. It's why you can't smell your own home, your own perfume after an hour, or your own skin.
Now combine that with something else. Beginning around age 40, skin chemistry changes. Research published in the Journal of Investigative Dermatology identified a compound called 2-nonenal that appears on the skin of adults over 40 and was essentially absent in younger subjects. It has a distinct greasy, grassy, slightly musty odor. In Japan, where it was first studied, it even has its own word: kareishū (加齢臭), which means "aging odor."
Put the two together and you get the cruelest part:
You develop a new, persistent odor at exactly the age your nose stops being able to detect it on yourself.
Your spouse notices. Your kids notice. Your grandkids notice. And out of politeness, almost none of them will ever say a word. The pillowcase, the towels, the collar of a jacket all carry it. You just can't smell it.
It hides in fabric first. Most people discover it exactly like this.
What Nonenal Actually Is (and Why It's Not Your Fault)
Nonenal is not a hygiene problem. It's a chemistry problem.
How it forms on your skin
- With age, your skin produces more of certain fatty acids (like palmitoleic acid) in its natural oils.
- At the same time, your skin's natural antioxidant defenses decline.
- With less protection, those fatty acids oxidize on the skin's surface.
- The oxidation byproduct is 2-nonenal, a waxy, oily compound with that unmistakable "older" smell.
Notice what's not on that list: sweating, skipping showers, or anything you did wrong. Nonenal shows up on people who shower twice a day and wear expensive cologne. Which brings us to the real problem.
Why Your Soap Isn't Working (Even the Expensive One)
Left: water and regular soap roll off the waxy nonenal film. Right: persimmon tannin binds it and carries it away.
Regular body odor is mostly water-soluble. Soap and water handle it. That's what soap was designed for.
Nonenal is different. It's an oily, waxy lipid that bonds to the skin's surface and to fabric. Water rolls off it. Standard surfactants only partially lift it. So you step out of the shower feeling clean, and within hours the compound your soap never fully removed is noticeable again. On you, and slowly baked into your towels and sheets.
Deodorants and fragrance make it worse, not better: perfume layered over nonenal creates that specific "cologne over mustiness" note most of us can instantly recall from childhood visits to older relatives. Covering it doesn't work. It has to be removed at the source.
The 500-Year-Old Japanese Answer
Kakishibu, fermented persimmon tannin, has been used in Japan since the samurai era.
Japan noticed this problem centuries before Western science named it. Their answer came from an unlikely place: the persimmon.
Fermented persimmon extract, known as kakishibu, is extraordinarily rich in a specific tannin. For hundreds of years it was used across Japan as a natural purifier and deodorizer: on fabric, on wood, and on skin. What modern chemistry later confirmed is why it works so well here:
Persimmon tannin binds directly to nonenal molecules and breaks them down into odorless components. It doesn't mask the smell. It doesn't perfume over it. It chemically neutralizes the compound itself. Then the wash carries it away.
This is also part of why "aging odor" is openly discussed and managed in Japan, while in the West most people over 40 have never even heard the word nonenal.
What CURO Did With It
CURO's Deodorizing Soap with Persimmon takes that traditional ingredient and builds a modern cleansing bar around it, formulated specifically for age-related odor:
- Japanese persimmon extract to bind and neutralize nonenal on contact
- Deep-cleansing base strong enough to lift the waxy lipid layer, gentle enough for daily use on mature skin
- No heavy fragrance, because the goal is the absence of odor, not a new one on top
| Regular soap | Deodorant / fragrance | Persimmon soap | |
|---|---|---|---|
| Removes sweat odor | ✓ | Masks only | ✓ |
| Removes waxy nonenal layer | ✗ | ✗ | ✓ |
| Neutralizes the compound itself | ✗ | ✗ | ✓ |
| Stops odor transferring to towels & bedding | ✗ | ✗ | ✓ |
Deodorizing Soap with Persimmon
From SFr. 23.99 · Free shipping on bundles · Ships from EU stock
Check Availability →60-day money-back guarantee. If you (or your family) don't notice the difference, you don't pay.
Where to Use It: The 5 Zones
Nonenal concentrates where skin oils naturally collect. Tap the pulsing points to see what accumulates where:
Tap each point · Most people notice the change on pillowcases and towels within two weeks
