Chris Callewaert studies body odor and the skin microbiome to find solutions against malodors.
Chris Callewaert
The Intriguing Link Between Earwax and Body Odor
While discussing earwax and body odor may be a subject of amusement or discomfort, these bodily secretions share more than meets the eye. Both are produced by apocrine glands and exhibit surprising consistency across individuals. People often note that individuals with sticky, honey-colored earwax often emit stronger armpit odors, whereas those with drier, flaky earwax tend to have more neutral body scents.
Unraveling the Genetic Factors
Curiosity drove researchers to explore the underlying genetics behind these observations. In 2006, scientists pinpointed the role of the ATP binding cassette subfamily C member 11 (ABCC11) gene in determining earwax type. A single nucleotide polymorphism (SNP)—a change from guanine (G) to adenine (A)—defines whether a person has wet (GG or GA) or dry (AA) earwax.
Julie Horvath, fascinated by microbes, studies the connection between host and microbial genetics.
Matt Zehrer
But the influence of the ABCC11 gene extends beyond earwax. According to Julie Horvath, a primate comparative genomics researcher at the University of North Carolina at Chapel Hill, “Microbe composition in both earwax and armpits is influenced by human ABCC11 genotype.“
The Role of ABCC11 in Microbial Diversity
The ABCC11 gene plays a crucial role in sweat transportation. It encodes a protein responsible for delivering protein- and lipid-rich molecules to the skin’s surface, serving as a resource for bacteria. As these lipids degrade, they produce volatile organic compounds, which predominantly contribute to body odor.
For individuals with dry earwax, the ABCC11 gene doesn’t function properly. Consequently, it restricts lipid delivery to the skin, thereby starving certain bacteria and reducing odor.
Chris Callewaert, a microbiologist at Ghent University, identified Staphylococcus and Corynebacterium as the predominant armpit microorganisms in his research. Corynebacterium is associated with pungent, musty, and fecal-like scents, while Staphylococcus produces more neutral odors, particularly in individuals lacking a functional ABCC11 gene.
The Armpit and Earwax Microbe Project
Horvath initiated the Armpit and Earwax Microbe Project in 2017, a citizen science endeavor aiming to explore the relationship between genetic variations and skin microbial composition. Her study revealed that individuals with similar genotypes exhibit shared yet distinct microbial profiles in both earwax and armpits.
Earwax type appears to correlate with the abundance of certain clinically relevant microorganisms. The findings highlight the intricate interplay between genetics and the human microbiome.
Other Factors Influencing Body Odor
While genetics play a significant role, they are not the sole determinant of body odor and microbial diversity on the skin. Factors such as gender, diet, age, immune health, and deodorant use also contribute to variations in these characteristics.
In the ongoing quest for a better understanding of the human microbiome, researchers are still uncovering the many nuances that influence our individual scents.
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