The Science Behind 'Old Person Smell': A Natural Biological Phenomenon
Can you recall the distinctive scent of a beloved grandparent or elderly relative? Many describe it as a blend of stale oil and musty cardboard, reminiscent of opening old books or unpacking vintage clothing. While more subtle than youthful body odor, this recognizable aroma is often filed away in memory as "old person smell." As it turns out, this scent is an actual biological phenomenon caused by epidermal changes that occur with aging.
The Chemical Culprit: 2-Nonenal
Research has identified the source of this aging odor as an organic compound called 2-nonenal (pronounced noh-neh-nahl), which belongs to a class of chemicals known as aldehydes. According to skin experts, every birthday after age 40 increases the likelihood of these skin changes that produce this distinctive scent.
"As we age, several things happen simultaneously in our skin," explained Dr. Sonal Choudhary, a dermatologist from the University of Pittsburgh School of Medicine. "Antioxidant defenses in the skin decline, the composition of our sebum changes, and our cumulative UV exposure and environmental stress increase oxidative damage in the skin."
Dr. Delphine J. Lee, chief of dermatology at Harbor-UCLA Medical Center, noted that not all aldehydes smell the same. For comparison, cinnamaldehyde gives cinnamon its characteristic aroma, while 2-nonenal produces that distinctive, dusty "granny" smell.
When and Why It Develops
The production of 2-nonenal increases gradually as people get older. "Research suggests measurable increases in 2-nonenal typically begin after age 40, with more noticeable accumulation in the 50s and beyond," Choudhary said. "It's a gradual process, not an instant switch."
Dermatologist Dr. Naana Boakye, founder of Bergen Dermatology, emphasized that this is a common age-related phenomenon. "Evidence suggests that 2-nonenal production is a common age-related phenomenon, not something limited to a small subset of people," she noted. "Studies consistently detect this grassy, greasy scent in older adults of both sexes."
Why You Might Not Notice It Yourself
Many people producing 2-nonenal may not detect it on themselves due to olfactory adaptation, where the brain filters out familiar scents. "People can exaggerate that this smell is unpleasant or disgusting," Lee said. "It may even be more neutral or pleasant than the body odors of younger and middle-aged people."
This gradual process allows your brain to become accustomed to the new scent, similar to how we might notice a friend's house scent but not our own home's unique aroma.
The Challenge of Removing the Scent
Unlike sweat, 2-nonenal doesn't wash off easily because it's a fatty acid that doesn't readily dissolve in soap and water. "It's hard to get rid of this molecule because it's very sticky," said Danielle Reed, chief science officer at Monell Chemical Senses Center. "It loves to stick to your skin and it loves to stick to fabrics."
Boakye suggested antioxidant-based cleansers and products containing tannins, which can bind aldehydes, might help reduce odor persistence. Persimmon soap, which contains tannins, has a long history of use though large clinical trials are lacking.
Emerging Research and Natural Acceptance
Recent research has explored eggplant extract's potential to reduce oxidative stress contributing to 2-nonenal formation. A study published last year found eggplant components exhibited excellent 2-nonenal scavenging activity. However, Lee cautioned that "human clinical data remain limited, so this should not be positioned as a cure."
Ultimately, experts agree there's no sure-fire way to completely eliminate this natural scent. "If you could figure this out, you'd be very rich, but so far there's nothing that's truly helpful," Reed said.
A Natural Part of Aging
Most importantly, this scent represents a normal biological change. "This is a normal biochemical change of aging skin, similar to wrinkles or dryness," Choudhary emphasized. "With thoughtful skin care, antioxidant support and proper laundering, it can often be minimized significantly."
Reed offered perspective on societal attitudes toward scents: "We've decided we don't like the odor of old people, but we love the odor of babies' heads. Perhaps, as a society, we could learn to love the smell of aging."
Lee concluded with a broader view of aging: "As a dermatologist, I emphasize that aging is a natural, lifelong biological process experienced by us all. We should focus on promoting health and well-being across our lifespans, while recognizing and valuing the wisdom, resilience and lived experience that accompany advancing age."
