Your funky belly button could hold vital clues about your health — including signs of Parkinson’s, which is notoriously hard to diagnose.

No single lab or test can confirm a Parkinson’s diagnosis, and doctors are left to rely on symptoms, medical history, and tests like MRIs to rule out other conditions. Sometimes it can take years to get answers.

In fact, people send their T-shirts to a woman in Scotland named Joy Milne, who claims she can sniff out the condition long before symptoms appear.

She smelled it first on her husband about a decade before he was diagnosed with Parkinson’s. Milne was even put to the test at The University of Edinburgh — and nosed out who had the disease with “incredible” accuracy.

New research is uncovering how Parkinson’s may leave a detectable chemical signature in body odor, and opening the door to earlier and more accessible diagnoses — without shipping to Scotland.

What the research showed

All day, every day, your body is producing oil, sweat, and dead skin. Everything from what you eat to the medications you take are processed by the body and come out in these secretions, plus your breath, urine, and saliva.

Most of this stuff gets removed by cleaning every day. What researchers deliberately tested here were places that escape regular cleaning: the belly button, inside the nose, and bowl-shaped area outside the ear canal.

So even with exceptional cleaning, smells usually accumulate in these areas. They are “less exposed to perfume, soap, and other factors,” they explain, which makes them “an easily accessible source of human body odor volatilome,” aka bodily smells.

Researchers in Germany looked at volatile organic compounds, or VOCs, chemicals that evaporate into the air at room temperature. Many have strong smells — like perfumes, fresh paint and some glues — but others can’t be detected by smell.

They swabbed 24 participants — six with Parkinson’s, six with mild cognitive impairment, six with COVID-19 and six healthy control participants.

Researchers blasted the swabs with highly purified air, making the VOCs come out to be analyzed by lasers. They were able to get a kind of fingerprint of the mix of VOCs in each swab, and compare swabs to each other to see if there were any in common.

They found each group patterns across each participant’s fingerprints. They even tested several more Parkinson’s participants a few weeks later to see if the results would be consistent, and they were.

Why it matters

This was a very small study with only two dozen participants, so we can’t say yet that this will be the new way to diagnose Parkinson’s — or COVID-19, or cognitive impairment.

However, it did its job as a proof of concept: showing that non-invasive sampling combined with laser spectroscopy might form the basis of a screening tool in the future.

Scientists say future research will need to test larger populations, especially to determine whether the patterns seen here were a result of Parkinson’s, aging, or a combination of both. That means comparing people of similar ages with and without Parkinson’s.

Further research also will need “real world” testing that deals with the reality of variable soap, perfumes, hygiene, and other contaminants that might affect this kind of test.