Lately, I’ve received numerous inquiries from customers regarding the phenomenon often referred to as “old person smell.” Many have also asked about a particular persimmon soap trending on Instagram that claims to eliminate 97% of the odor-causing compound. Spending quality time with my 86-year-old Dad, who sometimes smells wonderfully fresh and other times less so, prompted me to investigate the validity of this claim. After thoroughly reviewing the research available, I discovered that the scientific support for this assertion is surprisingly limited.

Understanding “Old Person Smell”: Is It a Real Phenomenon?

Throughout my experience caring for numerous elderly individuals, including my father and patients in the emergency room, I’ve noticed a wide variety of body odors. Some individuals maintain a pleasant scent, while others do not. In my informed opinion, there isn’t a singular “Old Person Smell.” Each elderly person has a distinct scent, ranging from pleasant to unpleasant. While research indicates that body odor can change with aging, this does not imply that all older adults share a specific odor profile or that one particular molecule is solely responsible for it.

What Role Does 2-Nonenal Play in Aging and Body Odor?

Research suggests that a compound known as 2-nonenal (or trans-2-nonenal) may increase with age and could contribute to changes in body odor among older adults. The pivotal study highlighting this was published in the Journal of Investigative Dermatology in 2001 by scientists at Shiseido, a renowned Japanese cosmetics firm. This study, which included only 22 subjects, found that when lipids on the skin oxidize, a compound with a greasy, grassy scent, 2-nonenal, is produced. It was observed that the “amount of 2-nonenal tends to increase with aging.”

In summary, this study is over 25 years old, involved only 22 participants, and was funded by a cosmetics company, showing a compound that merely “tends” to increase after the age of 40. Oddly, despite this finding, there has been a lack of follow-up studies. One of the few studies I found evaluated the effects of an antifungal soap on 54 elderly individuals who bathed biweekly, yet it did not mention 2-nonenal among the nine body odor compounds detected. Isn’t it curious that if a distinct “old person smell” had been firmly established, there wouldn’t be more scientific inquiries to support and explore it further?

Evaluating the Evidence Linking 2-Nonenal to “Old Person Smell”

The evidence is weak. Unfortunately, one company claims that “old person smell” stems from a single compound, leading many to accept this as fact, despite the outdated and uncertain science behind it. My assessment, after extensive online research, is that 2-nonenal may be one of many substances that contribute to unpleasant odors in elderly individuals, and that a preliminary scientific observation has been exaggerated into a more compelling marketing claim than the evidence truly supports.

It’s also important to clarify, as I’ve seen on Instagram, that there’s nothing unique about the skin at the base of the skull or behind the ears that leads to “old person smell.” The skin in these areas has a higher concentration of sebaceous and eccrine glands, which made them targets in one study, but there is no “old person smell gland” in these regions. Such areas may be overlooked during washing, allowing odor-producing compounds to accumulate.

Can Persimmon Soap Effectively Eliminate 2-Nonenal?

A leading company selling persimmon soap asserts that its product can eradicate up to 97% of nonenal. They attribute this figure to testing conducted at a partner lab in Japan; however, I could not locate any publicly accessible, peer-reviewed studies detailing the test, methodology, or outcomes. If the claim is substantiated by solid data, it should be available for public and scientific scrutiny.

While I believe that persimmon soap does remove 2-nonenal and other odor compounds effectively, there is no scientific evidence publicly available demonstrating that persimmon soap specifically targets and eliminates 2-nonenal more effectively than standard soap. To clarify, persimmon soaps have received excellent reviews, so please do not misconstrue this article as criticism of persimmon soap; my aim is simply to address the inquiries I frequently receive.

The timeline of events raises some concerns:

1999–2001: Researchers at a Japanese cosmetics firm identify 2-nonenal as a potential factor in age-related body odor based on a very small study. The company also coined the Japanese term for “aging odor” and subsequently developed products aimed at reducing or masking it.

2012: The only human study I could find involving a persimmon-containing soap focused on 20 men aged 43–75. They used a soap blended with persimmon and three other polyphenol-rich plant extracts daily for four weeks, resulting in a significant decrease in 2-nonenal levels. there was no control group using the same soap without the polyphenol complex, only persimmon extract, or standard soap without persimmon. Thus, the study cannot determine whether persimmon was the reason for the improvement or if daily washing would have yielded similar results.

2014–present: Persimmon soaps targeting “aging odor” have gained popularity in the U.S., with some brands using terms like Nonenal® and “Nonenal® Aging Odor” in their marketing. One company has even filed for a U.S. trademark for the term NONENAL in connection with soaps, body washes, and cosmetics. Meanwhile, many similar products echo these claims, which seem significantly stronger than the scientific evidence available.

Can Regular Soap Effectively Eliminate 2-Nonenal?

Currently, there is no substantial published data to answer this question. The persimmon soap company asserts that “other” soaps only remove 35% of 2-nonenal, yet describes “other” soaps as “not tested,” “not approved,” and “chemical.” It remains unclear which “other” soap they referenced, as the data is not publicly accessible.

My common-sense approach suggests that for 2-nonenal to form, oxidized lipids (fats) must be present on the skin. When you wash your skin with soap, you effectively remove many of these surface lipids along with any associated odor compounds. Regular washing, such as daily showers, consistently eliminates both the material that can lead to 2-nonenal formation and any existing 2-nonenal on your skin. Ordinary soap (including Osmia soap) is specifically formulated to emulsify and remove oils, doing so efficiently.

What Other Factors Contribute to Body Odor in Older Adults?

Many factors contribute to body odor across different age groups! Thousands of volatile organic compounds are produced by the human body, many of which can influence our scent.

Infrequent Bathing and Hygiene Changes

My father, for reasons I cannot fully understand, has become resistant to showering. It could be due to physical stiffness or weakness, or perhaps he enjoys watching his favorite shows like Murder, She Wrote, which he loves! Another possibility is that his diminished sense of smell prevents him from noticing when he begins to emit an odor. Reduced hygiene and resistance to bathing are also common in individuals with cognitive impairments like Alzheimer’s disease.

Dental Health, Dry Mouth, and Dentures

According to Memon et al., “80% to 90% of halitosis is due to intra-oral factors,” with a coated tongue, periodontal disease, and poor oral hygiene being primary contributors. When oral care is neglected, it can lead to unpleasant odors.

Urinary Incontinence

From my experience working in hospitals and nursing homes, I can attest that once the strong scent of urine enters your nostrils, it can linger for days. Even a minor amount of leaking urine can create a noticeable odor detectable from several feet away. This is a potent and distinct smell, especially when it has been allowed to fester.

Soiled Clothing, Bedding, and Household Fabrics

As bathing frequency often declines with age, so can the regularity of laundry and cleaning. Clothing, bed linens, and furniture absorb oils from skin and hair, and if not washed regularly, these oils can oxidize and develop unpleasant odors, contributing to the perception of an “old person smell.”

Diet, Medications, and Health Conditions

Certain foods like garlic and onions, as well as alcohol, can significantly influence body odor. Some medications can increase sweating, which may worsen body odor. Although I do not believe there is a singular scent tied to aging, various illnesses can alter the volatile compounds emitted by the body. Conditions such as cancer, metabolic disorders, liver or kidney diseases, infections, and others can all affect how a person smells.

Is Special Soap Necessary for Addressing “Old Person Smell”?

Let me be clear: you do NOT require a specialized soap to combat “old person smell,” and it frustrates me that companies are making you feel as if you do. Am I suggesting that persimmon soap won’t improve your scent? Not at all. It has positive reviews on Amazon and may be a delightful product that many enjoy. robust evidence does not support its claim to achieve results that no other soap can provide.

Additionally, I feel compelled to express my frustration with yet another assault on aging perpetuated by the beauty industry. While this message is distinct from the narrative that one must appear younger to be beautiful, the underlying strategy remains unsettlingly similar: identify an age-related change, instill fear or shame about it, and then market a product to resolve it.

Everyone deserves the right to embrace aging in their own way, and there is absolutely nothing wrong with wanting to smell clean and fresh. it is crucial to recognize how industry influences our collective perception of aging and ensure that your attitude towards aging is uniquely your own.

Practical Tips for Preventing “Old Person Smell” as You Age

Here’s a practical checklist for seniors—whether you are one or caring for someone—to help maintain a fresh and healthy scent!

• Shower more frequently, ideally daily. While this may be challenging, shower chairs and assistance can make it easier!

• For sensitive or delicate skin, opt for unscented soap and follow up with an unscented lotion or body oil to retain moisture and support skin barrier function.

• Maintain oral hygiene, and avoid wearing dentures overnight.

• Change underwear, socks, and shirts daily, and wash pajamas, robes, towels, and bedding regularly.

• Pay special attention to areas that are easily overlooked, such as behind the ears, back of the neck, under the breasts, skin folds, feet, groin, and underarms.

• If urinary incontinence is an issue, promptly change pads or underwear and gently but thoroughly cleanse the skin.

• Ensure frequently used chairs, cushions, mattresses, and other fabrics are cleaned regularly, as they can absorb body oils and odors over time.

• Stay hydrated, as dry mouth can contribute to bad breath.

• If you notice sudden changes in body odor, or if it becomes unusually strong or different, consult a healthcare provider. Medications, infections, metabolic conditions, and other health issues can alter body scent.

• Lastly, don’t stress over 2-nonenal. Regular, mindful hygiene practices are far more crucial than purchasing a specialized soap for a compound that may not be produced in significant quantities.
  

With love and a delightful scent until the very end,

The information in this post is intended solely for educational purposes and should not be used for diagnosing or treating any physical or mental conditions, diseases, or skin issues.

References:

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Nalcaci R, Baran I. Oral malodor and removable complete dentures in the elderly. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008 Jun;105(6):e5-9.

Memon MA, Memon HA, Muhammad FE, Fahad S, Siddiqui A, Lee KY, Tahir MJ, Yousaf Z. Aetiology and associations of halitosis: A systematic review. Oral Dis. 2023 May;29(4):1432-1438

Ishino K, Wakita C, Shibata T, Toyokuni S, Machida S, Matsuda S, Matsuda T, Uchida K. Lipid peroxidation generates body odor component trans-2-nonenal covalently bound to protein in vivo. J Biol Chem. 2010 May 14;285(20)

Tatsuguchi I, Matsuoka T, Izumi R, Ijichi S, Shibata H. Preventive effect against the aged men’s body odor by the soap containing polyphenol. J Japan Association on Odor Environment. 2012;43(5):362–366.