Volunteers have sniffed the body odor of infants and teenagers, and it’s no surprise that they found that young children smell “like flowers” while teenagers smell “like goats.”
Many of us are familiar with the sweet scent of babies, while it’s hard not to grimace at the odor of a sweating teenager who hasn’t used deodorant.
Scientists have identified the chemicals that make teenagers “smelly.” (Source: iStock).
Previous studies have also found that parents prefer the scent of infants over that of teenagers, which may influence their emotional bonding with their children.
Attracted by the role of scent in relationships, the lead author of the study, Helene Loos, a scent scientist at Friedrich Alexander University in Germany, conducted a study aimed at exploring the changes in body odor (BO) throughout a person’s life.
Helene Loos and her colleagues prepared T-shirts with cotton pads sewn into the armpits for 18 infants aged 0-3 years and 18 teenagers aged 14-18 participating in the study.
After the participants wore the T-shirts overnight, the researchers collected samples of the odorous substances that had absorbed into the cotton pads.
The scientists used gas chromatography, a technique for separating chemicals with different properties, to isolate and detect the individual odor compounds in each BO sample. They then asked volunteers to smell and describe the scent of each substance.
Loos noted that 42 odor compounds were identified, and both age groups produced most of them.
Infants have a sweet, fragrant scent. (Photo: iStock).
She also pointed out that a single odor compound can activate multiple scent receptors in the nose, and the combination of many odor compounds can trigger unique and complex patterns of activity unlike that of an individual compound.
However, the components of the fragrance will affect whether it smells pleasant or unpleasant to the person smelling it.
Loos commented on the odor compounds discovered: “We were not surprised by the overall findings, but it is interesting to see the rich diversity of compounds.”
Among these, a group of compounds known as aldehydes was the most diverse, producing scents “like cardboard,” “fried food,” and “hazelnut.”
BO in both age groups also contained carboxylic acids, a type of organic compound. Some were quite pleasant, emitting fruity scents or “like dried plums.” Others were less pleasant, with “cheesy,” “moldy” scents or “goat-like” odors.
The research team diluted each carboxylic acid multiple times to assess the contribution of each acid to BO in both groups.
Carboxylic acids from teenagers’ armpits retained their scent even after dilution, in contrast to those from infants, suggesting that these chemicals may be secreted at higher concentrations after puberty.
Teenage BO also contained two types of steroids not found in infants’ samples. One had a scent similar to sandalwood, a common fragrance in perfumes. The other smelled like sweat and urinals.
Teenage BO contains two types of steroids not in infants’ samples. (Source: Getty Images).
Changes in human BO from infancy to puberty may relate to changes in their skin, including hormonal shifts; alterations in lipid and fat composition on the epidermis; differences in skin microbiota; or activation of sweat and sebaceous glands secreting lipids.
Loos mentioned that while studying the natural body odors of participants, the scientists carefully considered “all potential sources of contamination.” They asked parents of infants and teenagers to avoid strong-smelling foods and spices, such as onions or garlic, and to provide unscented soaps and detergents for both groups.
However, many odor compounds found in BO samples were also detected in these unscented soaps and detergents, so it is unclear how much they influenced the research results.
In addition to the T-shirts with odor-absorbing cotton pads in the armpits, the researchers also provided each participant with a second T-shirt to be kept in the room. Most of the 42 odor compounds were also found in these unworn T-shirts, but it is unclear whether they permeated from the participants or came from another source.
Some chemicals previously linked to BO were not detected in this study, including acetic acid, which gives vinegar its characteristic smell. This may be explained by the small, non-diverse participant group or the fact that different techniques have varying capabilities for detecting different substances.
Loos and her colleagues plan to use other methods to obtain more types of odor compounds, as well as to explore how BO changes in different age groups, including older adults.
They also want to study higher-intensity BO in individuals after exercising or after multiple nights of sleep.
