Aging Odor (Nonenal): Is It Real, What Causes It, and What Actually Helps

Short answer: Yes, aging odor is real. From around age 40, the oils on the skin change and oxidize more easily, producing a compound called 2-nonenal that gives body odor a faint greasy, grassy note. It is not caused by poor hygiene, it is not the same as sweat odor, and it can be reduced with the right washing routine.

Written by the NENALI team. We make a persimmon soap, so we have a stake in this topic: every scientific claim below names its source so you can check it yourself. Last reviewed: October 2026.

Is aging odor real?

Yes. It was measured in 2001 by a team of Japanese researchers led by Shinichiro Haze. They collected the body odor of people aged 26 to 75 and analyzed it by gas chromatography. One compound, 2-nonenal, was detected only in the participants aged 40 and older, and it tended to increase with age (Haze et al., Journal of Investigative Dermatology, 2001). In Japan the phenomenon has its own word, kareishu.

What causes aging odor?

Your skin makes its own oils. Among them are omega-7 unsaturated fatty acids, which react with oxygen: the same reaction that changes a bottle of oil left open on the counter. The 2001 study found that omega-7 fatty acids and lipid peroxides on the skin surface both increase with age, and that 2-nonenal forms when those fatty acids break down by oxidation.

That is why aging odor is different from sweat odor. Sweat odor comes from bacteria breaking down sweat, mostly under the arms. Aging odor comes from skin oils meeting oxygen, with no sweat required, and it appears wherever those oils concentrate: the neck, chest, back and behind the ears.

At what age does aging odor start?

In the original study, 2-nonenal was found only in people aged 40 and over. It does not switch on at a birthday. It builds gradually, and the amount varies from person to person.

What does aging odor smell like?

Researchers describe 2-nonenal as greasy and grassy. People more often describe a stale, slightly waxy note, like an old book or cooking oil that has been open too long. It is usually faint rather than strong, but it is persistent, and it clings to fabric.

Is "old person smell" a hygiene problem?

No. "Old person smell" is an unkind name for a normal change in skin chemistry, and it has nothing to do with being unclean. In a 2012 study, volunteers smelled body odor samples from three age groups. They could tell the oldest group (aged 75 to 95) apart, and they rated those samples as less intense and less unpleasant than the samples from young and middle-aged adults (Mitro et al., PLoS ONE, 2012).

Why can't I smell it on myself?

Because the nose stops registering a smell it is constantly surrounded by. Fabric, on the other hand, holds the odor and hands it back concentrated. A shirt collar in the evening or a pillowcase in the morning is how most people first notice it.

Why doesn't showering more often get rid of it?

Because it is not a cleanliness problem. The skin keeps producing the compound, so it returns between washes. Washing harder or more often does not change the chemistry. It mostly dries the skin out. Perfume and a stronger deodorant do not solve it either: one covers the smell, and the other is built for sweat bacteria.

How to get rid of aging odor

You cannot switch off the chemistry, but you can reduce how much of the compound stays on your skin and in your fabrics.

1. Wash the right places, with contact time. Neck, chest, back, behind the ears, under-bust and underarms. Lather, then leave it on for twenty to thirty seconds before rinsing.
2. Use a soap made for 2-nonenal. The ingredients with research behind them are plant polyphenols. In a four-week study, 20 men aged 43 to 75 used a soap containing polyphenols from astringent persimmon and three teas every day, and the amount of 2-nonenal measured from their bodies fell significantly (Tatsuguchi et al., Journal of Japan Association on Odor Environment, 2012). The study was small and company-run, but it is the idea behind persimmon soap.
3. Look after fabric. Change pillowcases often and wash collars, undershirts and bedding regularly, because the odor builds up there.
4. Keep your deodorant for sweat. It does a different job, so use both rather than one instead of the other.
5. Do not over-scrub. Mature skin is drier, and harsh washing makes that worse without removing the cause.

A sudden or strong change in body odor is different. Mention it to a doctor, because it can have a medical cause that no soap addresses.

Does a body wash or deodorant work for aging odor?

A body wash can, if it is built on the same ingredients as the soap. The format matters less than the formula and the contact time. A standard deodorant or antiperspirant targets sweat and the bacteria that feed on it, so it helps with underarm odor but not with the compound that forms on the neck, chest and back.

NENALI makes three products on one persimmon tannin base: the Reset Aging Odor Soap, the Daily Wash body wash and a Full-Body Deodorant. Each comes with a 60-day money-back guarantee.

Frequently asked questions

What is nonenal?

2-Nonenal is an unsaturated aldehyde produced when omega-7 fatty acids on the skin oxidize. It was identified in human body odor in 2001 and is the compound most associated with aging odor.

Is aging odor the same as kareishu?

Yes. Kareishu is the Japanese word for age-related body odor, and it is the term used in much of the Japanese research on 2-nonenal.

Does aging odor mean something is wrong with my health?

No. A gradual change in body odor from around 40 is a normal part of aging skin. A sudden or strong change is different and is worth mentioning to a doctor.

Does regular soap remove aging odor?

Only briefly. Regular soap washes the surface, but the skin keeps producing 2-nonenal, so the odor returns between washes.

What is the best soap for aging odor?

Look for a soap made for 2-nonenal, with plant polyphenols such as persimmon tannin and green tea extract, a moisturizing base and little fragrance. Use it daily and give it about four weeks.

Related guides

• Persimmon soap: what it is, benefits and whether it works
• Aging odor soap: how to choose one that works

Sources

1. Haze S, Gozu Y, Nakamura S, Kohno Y, Sawano K, Ohta H, Yamazaki K. 2-Nonenal newly found in human body odor tends to increase with aging. Journal of Investigative Dermatology. 2001;116(4):520–524. doi:10.1046/j.0022-202x.2001.01287.x
2. Mitro S, Gordon AR, Olsson MJ, Lundström JN. The smell of age: perception and discrimination of body odors of different ages. PLoS ONE. 2012;7(5):e38110. doi:10.1371/journal.pone.0038110
3. Tatsuguchi I, Matsuoka T, Izumi R, Ijichi S, Shibata H. Preventive effect against the aged men's body odor by the soap containing polyphenol. Journal of Japan Association on Odor Environment. 2012;43(5):362–366. doi:10.2171/jao.43.362

NENALI products are cosmetics. They are not intended to diagnose, treat, cure or prevent any disease.