Anyone who has ever visited a nursing home will know that old people often seem to produce a strong, recognizable smell. Part of this is the natural consequence of having lots of people living together. However, research has shown that there may be an actual chemical cause.
The phenomenon is clearly broad and not limited to the United States. For one thing, there is actually a specific word in Japan just for the smell produced by old people, kareishu. Perhaps it is unsurprising, considering the very large number of retirees in Japan and the ageing population there.
Consequently, The Monell Chemical Senses Center in Philadelphia ran a study to determine the truth behind it. Surprisingly, its studies showed that people could actually identify and differentiate smells based on the age of the person. Its results were interesting in other ways too.
The studies led to a research paper, whose senior author Johan Lundström said, “Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid sick individuals, pick a suitable partner and distinguish kin from non-kin.”
The study was straightforward, done by collecting body odor samples from varying age groups. Each person donating body odor wore nursing pads in their clothes while they slept for five days, which absorbed their scent. Subsequently, the pads were cut up and placed into jars.
Then, a second group of participants had to comment on the intensity and unpleasantness of the odor in each jar they were given. In addition, each person had to figure out which age group the jar’s odor had come from. Notably, the second group of participants were all between 20 and 30 years old.
In essence, the study showed that participants could identify the smell of an old person more accurately than they could any other age group’s. Significantly, participants found it more difficult to differentiate between young and middle-aged people’s smells. However, they did not find old people smelled more unpleasant.
Study author Lundström said, “Elderly people have a discernible underarm odor that younger people consider to be fairly neutral and not very unpleasant. However, it is possible that other sources of body odors, such as skin or breath, may have different qualities.”
Lundström continued, “At the moment, the most interesting implication of this study is that this might be another signal that we can extract and use from body odors. We now know that we can extract information about the senders genetic composition, kinship, sickness and age.”
Nonenal is the name of the the chemical that produces the smell. It gets stronger as folk grow older, which is why participants in Lundström’s study could identify it. In fact, the National Institutes of Health describes it as a grassy or greasy odor.
Curiously, nonenal is also very difficult to smell if you are personally the source. Another key point is that nonenal is said to thrive in closed-off areas, making nursing homes a prime spot for the odor. This goes a long way in explaining why nursing homes are often strong smelling to visitors.
Nonenal is produced by our bodies when we get older, as skin glands make fatty acid. Eventually, this fatty acid becomes unsaturated aldehyde. The older we get, the more this process occurs, meaning more nonenal and a stronger smell that’s tough to cover up.
Unfortunately, because nonenal is oil based, it’s actually very difficult to clean off skin. This is especially true if the person is only using regular soap or toiletries. This means that not only do older people smell more, but it becomes harder and harder to remove the nonenal causing it.
Considering they are the origin of the word kareishu, it is unsurprising that a Japanese company have worked on a solution. As a result, the Mirai Clinical cosmetic firm has released a new product. It is marketed to tackle the problem of the smell caused by nonenal.
In its line of anti-ageing products, Mirai Clinical adds persimmon to combat nonenal. Basically, the tannin contained in persimmon extract can actually dissolve nonenal and work as a deodorizer. Together with special soap and other body washes, Mirai hopes to tackle kareishu head on.
Obviously, some people find it offensive to complain about the smell of old people. In other words it’s disrespectful, since if you bought this type of product for an elderly relative, they’d likely be offended. And old people may not feel comfortable buying it for themselves, perhaps feeling embarrassed.
At the same time, elderly people aren’t the only ones to suffer from unwanted nonenal build-up. It can also be an issue for women going through menopause. In this case, hot flashes and stress can both lead to changes in body odor for women.
Despite all of the talk about nonenal smelling unpleasant, Lundström’s research team uncovered something else. Chiefly, that differences in age and smell are possible reasons women can be attracted to older men. That is to say, changes in body odor might not always be a bad thing.
Lundström’s research report stated, “The ‘good genes’ model has been put forth as an explanation for why female animals are attracted to the odors of older males or why female insects prefer the sex pheromone from older male insects. Signals indicating old age, supposedly regulated by the immune system, are favored.”
The report continued, “[This is] due to the likelihood that individuals who reach old age possess a strong and adaptive immune system, as well as other adaptive advantages that have allowed them to grow older than their peers.” At least for men, they might not want to wash off nonenal after all.