What do you dread the most about growing old? Is it the aching muscles after what used to be an easy exercise routine? The need to get up and pee multiple times during the night? Or how about that distinctive “old-person smell” that sneaks into the air whenever a senior citizen is around?

Speaking of that last one, have you ever wondered where that particular odor comes from? Although many people believe that the source of the smell is behind the ears, a team of Japanese researchers have recently disproved this theory after what must have been an excruciatingly odoriferous ordeal. You might want to plug your nose for this one, folks–things are about to smell more than a little fishy around here…

As someone who works mostly with children and teenagers, I’ve never really been in a situation where I had to endure the so-called “old-person smell” for long periods of time. But the following tweets illustrate just how finely attuned others are to the unique smell:

▼”I sat down too quickly and was overcome by the smell of the old man sitting next to me (×_×)”

▼”The destructive power of the old-man smell shouldn’t be taken lightly (-_-)”


▼”A women who looked to be in her late 20s/early 30s was sitting next to me, but she smelled awful–about three times as bad as the younger guy over there. What’s up with that?”

In fact, Japan’s My Navi News recently surveyed 200 of its readers about unpleasant odors. A whopping 40.9% responded that the old-person smell bothered them the most–even more than the smell of sweat or the smell of cigarettes (both ranked in at 14.6%).

So what exactly causes this bothersome scent?

Japanese scientists have recently classified naturally occurring body odors into three main types: smells caused by sweat, smells caused by the chemical compound 2-nonenal (also known as the old-person smell, or 加齢臭 in Japanese), and smells caused by the chemical compound diacetyl (which gives middle-aged folk their own unique smell; the newly coined termed in Japanese is ミドル脂臭 / midoru shishuu). This last category is the result of new research and distinguishes between the body odors of middle-aged people and the elderly.

Let’s now take a look at each of the three categories.

First of all, 2-nonenal is responsible for the distinctive smell of elderly people. Although many people (at least within Japan) mistakenly believe that the odor emanates from behind a person’s ears, it actually comes from the back and central chest areas. If you smell something fishy behind the ears, it’s probably just the smell of perspiration, which occurs when odorless sweat rises to the surface of the skin and mixes with sebum and bacteria.

In addition to those two sources of body odor, Japanese researchers have just concluded that a third type of oily odor is present in middle-aged people due to the presence of a chemical compound called diacetyl. Diacetyl reaches its peak of production when people are in their late 30s or 40s, which is why it gained the nicknamed “the middle-aged person smell.” The chemical is said to be very volatile, and is over 100 times more easily diffused in an enclosed area than is nonenal. Articles have likened this third kind of smell to an old dresser or dead grass, also stating that women may be more sensitive to the smell than men.

▼We assume that “dead grass” means this kind of grass, and not the freshly mowed variety that seems to rank high on people’s lists of most pleasant smells.

Texture from Mayang's Textures

These discoveries about the middle-aged person smell came to light following the conclusion of a research study conducted by the Mandom Corporation (a Japanese manufacturer of hair care, skin care, perfumes, and deodorants), which lasted over seven years and involved approximately 800 middle-aged participants. In the study, researchers got up close (only three centimeters away!) to the participants’ heads, necks, and armpits, and took in big whiffs of body odor to try to pinpoint the source of the particular smell. Impressively, they were able to determine that the smell was strongest at the top and back of the head.

▼Don’t quit your day job, guys…err, wait, this is your day job…


Of course, people’s bodily scents can also vary depending on their individual diets and lifestyle choices. One Japanese source provides a list of tips for those self-conscious readers who wish to decrease their unpleasant natural scents:

  • For protein, eat more fish than meat, and even more soy products than fish.
  • Get plenty of antioxidants by eating dark-colored vegetables, sesame seeds, nuts, and citrus fruits.
  • Eat more brown rice.
  • Try to get at least six hours of sleep. If you don’t get enough sleep, your sebaceous glands will go into overdrive and production of the chemical 2-nonenal will increase.

We hope you’ve enjoyed this brief look at some of the science behind body odor. I’ve certainly gained an increased appreciation for the researchers who–quite literally–stick their noses into unwelcome places in the name of science!

Source: Naver Matome
Top image: Seesaa Blog
Insert images: Mayang’s TexturesDiamond Online