Just Read Today: A 2001 study in the Journal of Investigative Dermatology detected 2-nonenal in the body odor of participants aged 40 and older, but not in the younger participants studied. The researchers also found that omega-7 fatty acids and lipid peroxides increased in skin-surface lipids with age. They proposed that the oxidation of these fatty acids may generate 2-nonenal.pubmed.ncbi.nlm.nih
A later Japanese study tested a soap containing a mixture of polyphenols from tea and astringent persimmon. In a small four-week study involving 20 men aged 43 to 75, the amount of 2-nonenal decreased, and participants reported an improvement in odor. This is encouraging, but it is still a small study, not proof that all persimmon soaps work, or that persimmon is uniquely necessary.
Persimmon contains tannins and other polyphenols that may bind some odor molecules or provide antioxidant effects. The most reasonable conclusion is that a persimmon-containing cleanser may help reduce this particular odor for some people. It should not be advertised as a miracle treatment or as the only solution.
The name is also sometimes confused online. The main compound identified in the original aging-odor research is 2-nonenal, not “nonenal” as a vague marketing term. Some recent popular explanations have referred to 2-nonenol, but the best-known aging-odor research concerns 2-nonenal.pubmed.ncbi.nlm.nih
The Chemistry and Smell of Growing Older
Recently, I read about something called “aging odor”, a phrase that made me pause.
The article claimed that ordinary soap cannot remove the odor and that only persimmon soap can do the job. At first, I wondered whether this was another clever piece of advertising disguised as science. But behind the exaggerated claim there is a genuine chemical story, and as often happens with science the truth is more interesting than the advertisement.
The molecule most often associated with this odor is called 2-nonenal.
It is a small, volatile chemical produced when certain fatty substances on the surface of the skin undergo oxidation. In simpler language, some of the oils naturally present on our skin gradually react with oxygen. As we grow older, the composition of these skin oils may change, and the body’s antioxidant defenses may also become less efficient. One result can be the production of more 2-nonenal.
Scientists describe its smell in different ways: grassy, oily, stale, or slightly musty. In Japan, where the phenomenon has been discussed for many years, it is sometimes called kareishu, or “the scent of aging.”
The phrase itself is uncomfortable. It seems to reduce a long human life to a smell. Yet the chemistry is not a moral judgment. It does not mean that a person is dirty, careless, or neglecting personal hygiene. It is not evidence of failure. It is simply one possible consequence of the changes that accompany the passage of time.
A small molecule and a large subject
A 2001 study found 2-nonenal in the body odor of people aged 40 and older, while it was not detected in the younger participants examined in that study. The researchers connected the compound with the oxidation of omega-7 fatty acids present in skin-surface oils.pubmed.ncbi.nlm.nih
The study was important because it gave a chemical name to something that people had noticed but could not easily explain. Still, we should be careful. Human odor is never produced by one molecule alone. Sweat, skin bacteria, clothing, diet, medications, illness, household surroundings, and personal habits may all contribute.
Nor does everyone develop the same odor. Some older adults may produce more 2-nonenal, while others may not. Even among people of the same age, bodies differ.
Age is not a single biological event. It is a gradual collection of changes some visible, some invisible, some welcome, and some less welcome. Our skin becomes thinner and drier. Its texture changes. Hair may become silver. Muscle mass may decline unless we work to preserve it. The chemistry of the skin may also change in ways that we do not notice until someone else notices them for us.
What about persimmon soap?
The persimmon connection is not entirely fanciful.
Astringent persimmons contain tannins and other polyphenols. These substances may interact with odor-producing compounds and may also have antioxidant properties. A Japanese study tested a soap containing a mixture of polyphenols derived from tea and persimmon. After four weeks, the study reported a reduction in 2-nonenal and an improvement in perceived odor among 20 men between the ages of 43 and 75.
That is a useful finding, but it is not the same as saying that persimmon soap is the only effective remedy. The study was small, and the soap contained several plant-derived ingredients. We cannot assume that every bar labeled “persimmon soap” contains the same concentration or formulation.
Nor is ordinary soap entirely useless. Soap and water remove sweat, dirt, excess oils, and many odor-producing substances. A cleanser containing persimmon or other polyphenols may provide an additional benefit, but the claim that regular soap can never remove the odor is too strong.
The sensible approach is modest: wash gently, keep clothing and bedding clean, moisturize dry skin, and try a persimmon-based cleanser if one wishes to see whether it helps. It should not be used so aggressively that it irritates or dries the skin. A damaged skin barrier can create problems of its own.
The odor we cannot smell in ourselves
There is another curious feature of body odor: we may not notice our own.
The human brain becomes accustomed to familiar smells. The scent of our home, our clothing, and even our own body can fade into the background of consciousness. This may explain why a person can be unaware of a change that another person detects immediately.
That possibility calls for kindness from both sides.
If we notice a change in someone else, we should resist the temptation to turn it into a joke. If someone gently brings a change in our own odor to our attention, we should not automatically experience it as an insult. Bodies are not machines that remain unchanged simply because we would prefer them to do so.
Aging asks us to negotiate with change repeatedly. We adjust our glasses, our medications, our diets, our exercise, our sleep, and sometimes our expectations. We learn that maintenance is not vanity. It is one form of self-respect.
But we should also remember that no soap can preserve youth, and no fragrance can conceal the whole truth of a human life. A person is not a chemical compound.
Beyond the commercial message
The commercial message says: “Buy this special soap and erase the odor of aging.”
The scientific message is more restrained: a compound called 2-nonenal may increase in some people as the skin changes with age; persimmon-containing products may help reduce it; and the evidence remains limited.
The human message is larger still.
We are all living organisms, and living organisms change. The skin records time in wrinkles, dryness, pigment, texture, and sometimes scent. These changes are not signs that we have become less worthy of affection. They are traces of having occupied a body for many years.
I may try a persimmon soap. I may also continue using ordinary soap, clean clothes, fresh sheets, and a little common sense. But I hope I will not become so anxious about the chemistry of aging that I forget the deeper chemistry of human companionship, the warmth of a conversation, the comfort of friendship, the familiar presence of someone who has known us for a long time.
Perhaps the best response to aging odor is not embarrassment but attentiveness.
We can care for the body without declaring war on age.
AI Overview:
The chemistry of growing older is driven by cumulative molecular damage, oxidative stress, and epigenetic alterations that change how cells function. Research shows that this molecular aging is not entirely linear; humans experience rapid, dramatic biomolecular shifts and distinct aging waves in their mid-40s and early 60s.
- Oxidative Stress: Reactive oxygen species from normal metabolism damage lipids, proteins, and DNA over time.
- Glycation: Excess sugar molecules bind to proteins and lipids, forming advanced glycation end-products that stiffen tissues and blood vessels.
- Epigenetic Drift: Chemical tags on DNA shift as we age, altering gene expression and turning off protective cellular maintenance pathways.
- Inflammaging: A chronic, low-grade sterile inflammation builds up in tissues, fueled by cellular debris and a leaky gut barrier.
- Genomic Instability: Accumulated mutations break DNA strands faster than cells can fix them.
- Telomere Attrition: Protective chromosomal caps shorten with each cell division.
- Loss of Proteostasis: Damaged or misfolded proteins aggregate and disrupt cellular work.
- Mitochondrial Dysfunction: Energy production drops while toxic byproducts increase.
- Cellular Senescence: Damaged cells stop dividing and secrete inflammatory chemicals that harm neighboring tissue.
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