Belly Button Odor Could One Day Help Detect Parkinson's, Cognitive Impairment, and COVID-19

One day, medical professionals may sniff out diseases instead of relying on invasive tests to diagnose conditions. Our bodies emit various molecules depending on our lifestyle and metabolic state, some of which transform into gases that can be captured and analyzed to understand our health without a blood draw. Researchers from the Fraunhofer Institute for Integrated Circuits IIS in Germany gathered and tested scents from participants' belly buttons, inner noses, and outer ears.

In their study published in Scientific Reports, they found that the scent profiles of healthy individuals, participants with Parkinson's, mild cognitive impairment, or COVID-19 differed from one another, potentially leading to a new noninvasive diagnostic tool.

Traditionally, diagnosing a disease involves a range of tests, such as blood or tissue biopsies, to gather and analyze samples. However, researchers are exploring less invasive methods, including analyzing biofluids like sweat, urine, and saliva, and the odors our bodies release. These gases, known as volatile organic compounds (VOCs), are generated through normal metabolic processes and their profiles can vary between individuals based on factors like diet, lifestyle, and medical conditions, creating a unique scent "fingerprint" for each person.

The research team decided to collect samples from body parts least exposed to external influences, focusing on the inner nose, outer ear, and belly button. They swabbed these areas of 24 participants, with six having Parkinson's disease, six with mild cognitive impairment, six with COVID-19, and six serving as healthy controls. Samples were then analyzed using laser-based photoacoustic spectroscopy (LPAS), a method identifying VOCs by measuring sound waves produced when the sample absorbs light from a laser.

The results revealed distinct molecular profiles for people with Parkinson's, mild cognitive impairment, or COVID-19, with the most pronounced differences appearing in nasal and belly button swabs. Surprisingly, the clearest scent profiles emerged from healthy participants and those with cognitive impairment. Although the study has limitations, such as a small sample size and laboratory-controlled conditions, the researchers concluded that LPAS-based headspace analysis holds promise for detecting disease-associated spectral patterns, potentially paving the way for new diagnostic strategies in the future.