From Alzheimer’s to cancer, earwax can contain valuable indicators of a person’s health. Scientists are now analyzing its chemistry to find new ways of diagnosing diseases.
It’s orange, it’s sticky, and it’s probably the last thing you want to talk about in polite conversation. Yet earwax is increasingly attracting scientists’ attention, who believe it can help reveal insights into diseases and conditions like cancer, heart disease, and metabolic disorders such as type 2 diabetes.
The proper name for earwax is cerumen—a mix of secretions from two types of glands that line the outer ear canal: ceruminous and sebaceous glands. This mixture combines with hair, dead skin flakes, and other debris until it reaches the waxy consistency we know. Once formed, earwax is moved out of the ear by a “conveyer belt” mechanism, carrying skin cells outward at a rate of roughly one 20th of a millimeter per day. It can take months for the wax to travel from the inner ear to the outer ear.
While the primary function of earwax remains debated, it likely helps to keep the ear canal clean and lubricated. It also traps bacteria, fungi, and even insects, protecting the inner ear. However, despite its important role, earwax has long been overlooked by researchers studying bodily secretions.
That is beginning to change.
A Surprising Source of Health Clues
A surprising amount of personal information is hidden in earwax. For example, the vast majority of people of European or African descent have wet earwax (yellow or orange and sticky), whereas 95% of East Asian people have dry earwax (grey and non-sticky). This difference is controlled by the ABCC11 gene, which also influences armpit odor. Around 2% of people—mostly those with dry earwax—have a variant of this gene that results in no underarm odor.
More intriguing, earwax may reveal more serious health risks.
In 1971, Nicholas L. Petrakis, a professor of medicine at the University of California, San Francisco, found that Caucasian, African-American, and German women with wet earwax had approximately a four-fold higher chance of dying from breast cancer compared to Japanese and Taiwanese women with dry earwax.
Later, a 2010 study by researchers at the Tokyo Institute of Technology found that Japanese women with breast cancer were up to 77% more likely to have the gene coding for wet earwax than healthy volunteers. However, this link remains controversial; large-scale studies in Germany, Australia, and Italy have found no difference in breast cancer risk between wet and dry earwax groups.
Still, scientists are finding that earwax can reflect substances related to systemic illnesses more reliably.
Earwax and Diagnosing Diseases
Some rare genetic disorders, like maple syrup urine disease, can be diagnosed through earwax. This disorder prevents the body from breaking down certain amino acids, leading to a buildup of sotolone, a molecule responsible for the distinctive sweet smell (similar to maple syrup) found in the urine—and in the earwax—of affected individuals.
“The earwax literally smells like maple syrup,” says Rabi Ann Musah, an environmental chemist at Louisiana State University. “Within 12 hours of birth, smelling this distinct and lovely scent can reveal the disorder.”
Covid-19, diabetes, and certain heart diseases have also shown up in early studies as detectable through earwax samples. Similarly, Musah’s research identified lower levels of three fatty acids in the earwax of patients with Ménière’s disease, an inner ear condition causing vertigo and hearing loss. This discovery could lead to quicker, simpler diagnosis of a condition that usually takes years to confirm.
“Our interest in earwax as a reporter of disease,” Musah explains, “is focused on illnesses that are hard to diagnose with blood, urine, or cerebrospinal fluid tests, and which are rare or have slow diagnosis pathways.”
Why Earwax Works
Why does earwax store so much information? Nelson Roberto Antoniosi Filho, a chemistry professor at the Federal University of Goiás in Brazil, explains that many diseases—like cancer, diabetes, Parkinson’s, and Alzheimer’s—are fundamentally metabolic disorders. When metabolism changes, mitochondria behave differently, producing or stopping the production of certain chemical compounds. These changes can be captured in bodily fluids—and earwax, with its slow turnover, can preserve these markers longer and more reliably than blood or urine.
Bruce Kimball, a chemical ecologist at the Monell Chemical Senses Center in Philadelphia, agrees: “Earwax builds up slowly. It can capture long-term snapshots of metabolic changes.”
Developing the “Cerumenogram”
Recognizing this, Antoniosi Filho’s team developed the cerumenogram—a diagnostic test analyzing earwax for volatile organic compounds (VOCs) associated with disease. In a 2019 study, they collected earwax from 52 cancer patients (with lymphoma, carcinoma, or leukemia) and 50 healthy individuals. Using a technique that detects VOCs, they identified 27 compounds that acted as a “fingerprint” for cancer diagnosis, correctly predicting whether someone had cancer with 100% accuracy.
Interestingly, while the cerumenogram could detect cancer, it couldn’t distinguish between different cancer types—suggesting the metabolic changes causing these VOCs are common across cancers.
Antoniosi Filho believes that early detection could dramatically improve treatment success rates. In unpublished research, his team found that the cerumenogram could even detect pre-cancerous metabolic changes—before tumors form.
They are also exploring whether Parkinson’s disease and Alzheimer’s disease could be similarly diagnosed via earwax, although this research is in early stages.
In Brazil, the Amaral Carvalho Hospital has already adopted the cerumenogram for cancer diagnosis and monitoring.
Toward Routine Earwax Testing
Looking ahead, Antoniosi Filho envisions a future where the cerumenogram becomes a routine medical test, performed every six months, to screen for cancer, diabetes, Parkinson’s, Alzheimer’s, and other diseases—all from a small earwax sample.
Musah is also developing a quick, over-the-counter-style test for diagnosing Ménière’s disease, similar to Covid-19 home test kits.
Just observing three fatty acid levels in earwax has already opened new doors for diagnosis, treatment, and even understanding how our metabolism shifts over time.
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