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Our skin chemistry changes throughout life, and scientists have found that humans may even be able to recognize old age by scent alone. But before you start sniffing your favorite sweater suspiciously, there is an important twist: in blind tests, older people didn't smell worse.
There are certain milestones of getting older that most of us expect.
Reading glasses.
A few gray hairs.
Discovering that restaurant music is inexplicably louder than it used to be.
Developing strong opinions about pillows.
But picking up a favorite sweater one day and thinking:
Why does this smell slightly like my grandmother?
That one probably isn't in the retirement brochure.
Yet there really is some science behind the idea that people smell different as they grow older.
Our skin chemistry changes throughout life. The oils on our skin change. The activity of our sweat and sebaceous glands changes. The microorganisms living on our skin change too.
And together they help create something surprisingly personal:
our smell.
But the familiar stereotype of an unpleasant “old person smell” turns out to be much less scientifically convincing than you might imagine.
Indeed, one experiment produced almost exactly the opposite result.
First: Yes, Our Smell Really Does Change
Human body odor isn't one substance.
It is an extraordinarily complicated mixture of volatile chemicals produced by sweat glands, skin oils, bacteria and other biological processes.
Diet matters.
Smoking matters.
Health can matter.
Personal hygiene matters.
Genetics and the skin microbiome matter too.
And age appears to matter.
A comprehensive 2023 scientific review concluded that age is one of several intrinsic factors influencing body odor, alongside sex and other biological characteristics, while diet, health, climate and hygiene can also alter what we smell like.
So the idea that humans possess an unchanging personal scent from adolescence to old age is probably wrong.
We have something closer to a scent biography.
And one molecule has attracted a great deal of attention.
Meet 2-Nonenal
In 2001, Japanese researchers investigated body odor from 22 healthy people aged between 26 and 75.
The participants wore specially cleaned shirts for three nights, and researchers subsequently analyzed the volatile compounds captured in the fabric using gas chromatography and mass spectrometry.
One compound stood out.
2-nonenal.
It is an unsaturated aldehyde commonly described as having a greasy or grassy odor.
The researchers detected it in 69% of the participants aged 40 or over, but in none of the nine participants under 40.
They also found age-related changes in skin-surface fats and lipid oxidation.
Their laboratory experiments suggested a possible mechanism: certain omega-7 unsaturated fatty acids in the skin can undergo oxidative degradation, producing 2-nonenal in the process.
In other words, the distinctive scent may partly arise because the chemistry of our skin oils changes as we age.
Which is rather less insulting than saying Grandma forgot to shower.
Forty Is Not a Smell Deadline
The finding that 2-nonenal appeared in people over 40 has inevitably produced alarming headlines over the years.
But nobody wakes up on her 40th birthday emitting a new fragrance.
The original study contained only 22 participants, including just nine under 40.
And newer research suggests that human scent is more complicated than a single molecule.
A later study involving Caucasian participants found other volatile compounds that increased with age—including nonanal—but did not reproduce the original 2-nonenal result. A 2023 review suggested differences such as diet might partly explain the discrepancy.
So 2-nonenal is an interesting candidate in the chemistry of aging.
It is not a universal biological perfume that suddenly switches on at 40.
That is probably reassuring news for everyone approaching 39.
And especially for everyone who passed it some time ago.
Then Scientists Asked People to Sniff Each Other
This is where the research becomes considerably more entertaining.
In 2012, scientists asked whether people could actually recognize another person's age by smell alone.
They collected natural body odors from three groups:
young adults aged 20–30;
middle-aged adults aged 45–55;
and older adults aged 75–95.
The donors followed carefully controlled routines. They used odorless soap and shampoo, avoided alcohol, smoking and strongly scented foods, and slept for several nights wearing specially prepared T-shirts containing absorbent pads under the arms.
Researchers then combined samples from several donors so that one unusually pungent individual couldn't accidentally become the scientific representative of an entire generation.
Forty-one young adults were subsequently asked to smell the samples without knowing anything about the people who produced them.
The researchers wanted to know:
Could people smell age?
To some extent, yes.
Participants were particularly capable of grouping the oldest people's scents together and identifying them as coming from older adults more often than expected by chance.
So there does appear to be something distinctive about the natural scent of later life.
But then came the surprise.
Older People Didn't Smell Worse
The researchers asked participants to rate both the intensity and pleasantness of the different samples.
If the cultural stereotype were correct, you might expect the oldest group to perform rather badly.
They didn't.
The odors from the 75–95-year-olds were rated less intense and less unpleasant than those from the young and middle-aged groups.
The older people's odor was essentially rated as neutral.
And among the male samples, things became particularly awkward for middle age.
Middle-aged men's odor was rated the most unpleasant. Older men's odor was rated the most pleasant.
Somewhere, a 78-year-old gentleman is entitled to feel rather smug.
Among women the pattern was more complicated, and not every age comparison was statistically significant. The study was also small, so none of these findings should be turned into universal claims about which generation smells best.
But the main result is rather charming:
Older people smelled different. They did not smell especially bad.
Perhaps the Label Is Worse Than the Smell
The researchers themselves were surprised.
Popular descriptions of “old person smell” tend to assume that it is unpleasant.
Yet when people encountered older adults' body odor without knowing where it came from, the smell was rated neutrally.
That raises another fascinating possibility.
Perhaps part of our reaction isn't coming from the nose.
It is coming from the story we attach to what the nose detects.
Smell is unusually sensitive to context.
An odor described as cheese can evoke one response.
The same odor described as feet may receive a rather different reception.
The researchers noted previous evidence that simply attaching a negative label to an otherwise neutral odor can alter how pleasant people perceive it to be. They therefore suggested that knowing an odor came from an older person might itself influence the judgment.
That doesn't prove that age stereotypes cause negative reactions to older people's scent.
But it raises an interesting question:
Are we sometimes smelling the person—or our expectations about the person?
We All Have an Age-Related Smell
There is also something misleading about discussing “old person smell” as though distinctive body chemistry suddenly appears in later life.
Every stage of life has characteristic biology.
Babies smell different.
Puberty dramatically changes sweat and sebaceous-gland activity.
Adult body odor reflects hormones, bacteria, diet, environment and lifestyle.
Later in life, glandular activity and skin-lipid composition change again.
So perhaps it is more accurate to say:
Humans smell different at different ages.
Older adults haven't uniquely acquired body chemistry.
They simply possess the latest version.
Is It a Hygiene Problem?
Not necessarily.
Normal age-related changes in body odor are not evidence that someone is dirty.
Body odor originates partly from interactions among skin secretions, oils and microbes. Aging changes some of those ingredients before personal hygiene even enters the equation.
Obviously, ordinary bathing, clean clothing and clean bedding influence how people smell.
But specialized products marketed specifically to eliminate “old person smell” deserve more skepticism.
Some soaps and body washes claim to neutralize 2-nonenal. Persimmon-based soaps, in particular, are frequently promoted for this purpose.
The scientific evidence demonstrating that these products meaningfully eliminate age-related body odor in humans remains limited. The Guardian's experts likewise cautioned that such products have anecdotal support but little convincing clinical evidence.
So before spending a small fortune on anti-aging soap, it may be worth remembering what the blind experiment found.
Other people may be considerably less bothered by your scent than you are.
Our Noses Aren't Quite as Clever as We Think
There is another reason not to become too self-conscious.
Although the participants in the 2012 experiment showed some ability to distinguish older people's odors, their performance was far from extraordinary.
Some individual age comparisons initially reached statistical significance but failed to remain significant after adjustment for multiple testing.
The researchers themselves emphasized that the effects were modest and participants expressed little confidence in their judgments.
In normal life, things are considerably messier still.
Perfume.
Shampoo.
Laundry detergent.
Food.
Weather.
Medication.
Pets.
Restaurants.
Car seats.
That cardigan you really should have washed last Tuesday.
All of them become part of the enormous chemical cloud surrounding a human being.
So while age may leave a detectable olfactory fingerprint in laboratory conditions, nobody appears to possess a reliable biological age detector hidden inside her nose.
What Science Still Doesn't Know
For something every human carries around all day, body odor remains surprisingly under-researched.
The original 2-nonenal study involved only 22 people.
The age-recognition experiment involved 41 people doing the smelling.
The latter study's authors themselves acknowledged that lifestyle differences, medication among some older donors and the highly controlled collection procedure could have affected how well the results translate into ordinary life.
Researchers also still don't fully understand why some people's scent changes more noticeably than others.
Skin microbiome differences may matter.
Diet may matter.
Genetics may matter.
Health may matter.
Climate may matter.
And different populations may produce somewhat different chemical patterns.
So there is plenty still to sniff out.
Scientifically speaking.
Perhaps Aging Simply Has a Scent
There is something strangely intimate about smell.
We recognize the smell of someone's house.
A partner's pillow.
A baby's head.
A parent's coat.
An old book.
A grandmother's wardrobe.
Sometimes a smell can bring back a memory faster than a photograph.
So perhaps it shouldn't be surprising that our own scent changes as we move through life.
The chemistry is changing because we are changing.
Skin becomes different.
Hormones change.
Glands change.
Microbes change.
The body that carried us through 25 is not chemically identical to the body carrying us through 75.
Why should it smell exactly the same?
Lydia's™ Take
There is something rather wonderful about the fact that scientists once persuaded people aged up to 95 to sleep in specially prepared T-shirts so that strangers could later sniff them in the name of research.
And we should be grateful they did.
Because they discovered something unexpectedly reassuring.
Yes, older people appear to have a somewhat distinctive natural scent.
No, other people don't necessarily think it smells bad.
That seems worth remembering.
Growing older already comes with enough things to be unnecessarily self-conscious about without adding one's molecular aroma to the list.
Our skin changes.
Our hair changes.
Our faces change.
Apparently our chemistry changes too.
Perhaps aging isn't making us smell worse.
Perhaps after several decades on Earth, we simply acquire a slightly more complicated bouquet.
And if science eventually discovers that wisdom has a scent as well, Lydia™ will be sure to report it.
Editorial Note
This article discusses research into normal age-related changes in human body odor. Body odor can also be influenced by diet, medications, health conditions, hygiene and other factors. A sudden or unexplained change in body odor may therefore have causes unrelated to normal aging and can be discussed with a healthcare professional if there is concern.
Research & Trusted Sources
Haze S, Gozu Y, Nakamura S, et al. “2-Nonenal Newly Found in Human Body Odor Tends to Increase with Aging.” Journal of Investigative Dermatology (2001).
This small laboratory study of 22 adults identified age-related differences in 2-nonenal and proposed a biochemical pathway involving oxidation of omega-7 fatty acids in skin-surface lipids.
Mitro S, Gordon AR, Olsson MJ, Lundström JN. “The Smell of Age: Perception and Discrimination of Body Odors of Different Ages.” PLOS ONE (2012).
Researchers tested whether young adults could distinguish body odor from people of different ages. Older adults' odors were distinctive enough to aid age classification but were rated less intense and less unpleasant overall than odors from younger groups.
Di Cicco F, Evans RL, James AG, et al. “Intrinsic and extrinsic factors affecting axillary odor variation: A comprehensive review.” Physiology & Behavior (2023).
A broad review of factors influencing human body odor, including age, sex, microbiome, diet, health and hygiene. It also notes that later chemical studies have not uniformly replicated 2-nonenal as the defining marker of aging body odor.
The Guardian — “Do people really smell different as they get older? The truth behind ‘old person smell’” (2026).
The contemporary article that prompted this Lydia™ exploration, including interviews with clinicians and one of the researchers behind the age-discrimination experiment.