A few years ago, I stumbled upon one of those stories that makes you pause and say, "Nah... this can't be real."
It was about a Scottish woman named Joy Milne. For years, she insisted that her husband smelled different. Not bad. Just... different. She described it as a strange musky odor that wasn't there before. Friends brushed it off. Doctors certainly weren't interested.
Then her husband was diagnosed with Parkinson's disease.
That alone would have been an interesting coincidence. But things took an even stranger turn.
Researchers invited Joy to participate in an experiment. They gave her several T-shirts that had been worn by different people; some living with Parkinson's disease and others who were perfectly healthy. Without knowing who wore which shirt, she identified every Parkinson's patient correctly.
Well... almost.
There was one shirt she identified as belonging to someone with Parkinson's disease, but according to the researchers, the owner was healthy. They assumed she'd finally made a mistake.
About eight months later, the healthy volunteer was diagnosed with Parkinson's disease.
That was the day scientists stopped laughing.
Not long after reading that story, I came across another one on Reddit. A lady claimed she could tell whenever her boyfriend was about to have a seizure, not because he looked sick or complained of feeling unwell, but because of how he smelled.
She said it had happened repeatedly. Days before each seizure, she noticed a distinct scent coming from him. She even mentioned that she could identify people living with diabetes in the same way, although nobody around her seemed to notice anything unusual.
If you've spent enough time on the internet, you'll know that people claim all sorts of unbelievable things. But this one caught my attention because it reminded me of Joy Milne.
Could there actually be something to it?
As it turns out, science says... maybe.
Every second you're alive, your body is releasing thousands of tiny chemicals into the surrounding air. They leave through your breath, sweat, urine and even your skin. We don't see them, and most of us certainly don't smell them, but they're there. 1
Scientists call them volatile organic compounds, or VOCs.
Think of them as your body's invisible chemical signature.
Whenever something changes inside your body; whether it's an infection, cancer, diabetes or a neurological disorder, your metabolism changes too. Those metabolic changes alter the mixture of VOCs your body produces. In other words, disease can literally change the way you smell.
Doctors have known some of this for centuries without even knowing the chemistry behind it. Someone experiencing diabetic ketoacidosis often has breath that smells fruity because of acetone. Patients with severe kidney failure may develop breath that smells like ammonia.
Advanced liver disease can produce a sweet, musty odor known as fetor hepaticus.
Certain bacterial infections have such distinctive smells that experienced clinicians can sometimes recognize them before laboratory results arrive. Modern technology has shown that many diseases produce unique VOC patterns long before symptoms become obvious.
Researchers have identified characteristic chemical fingerprints for several cancers, Parkinson's disease, tuberculosis, and even Alzheimer's disease. Hospitals around the world are now testing electronic noses capable of detecting these invisible chemical signatures from nothing more than a person's breath.
It sounds like science fiction, but it's already happening.
So where do people like Joy Milne fit into all this?
Scientists believe that a very small number of people possess an unusually sensitive sense of smell, a condition known as hyperosmia. Their noses can detect concentrations of chemicals that most of us would never notice. What seems impossible to the average person may simply be another smell to them.
Animals have been exploiting this ability for years. Dogs can detect certain cancers, warn diabetic patients when their blood sugar is dropping, and even alert some epilepsy patients before a seizure occurs. They aren't performing miracles, but showing chemistry at play.
Which brings us back to that Reddit post. Can someone genuinely smell a seizure days before it happens?
At the moment, science doesn't have a definite answer. Researchers know that significant chemical and physiological changes occur before some seizures. Hormone levels shift. Brain activity changes. Stress hormones fluctuate. Any of these could potentially alter the VOCs released by the body.
Whether those changes begin several days earlier, and whether a few unusually sensitive individuals can detect them, remains an open question. But it is no longer an idea scientists dismiss outright.
Perhaps the most unsettling question of all is whether humans can smell death itself.
Hospice nurses sometimes describe a peculiar odor in patients who are approaching the end of life. Family members have reported noticing it too. While there is no single smell of death, the body's chemistry changes dramatically as organs begin to fail, cells break down, and bacteria alter their activity. Those processes create a different mixture of VOCs.
Whether a handful of people are naturally gifted enough to perceive those changes is still being investigated. The truth is, the human body has probably been broadcasting its internal condition through invisible chemical signals since the beginning of time.
We're only now developing the science and the technology to understand what those signals are saying.
So the next time someone tells you they can smell that something isn't right, don't be too quick to dismiss them.
History has already shown that sometimes, the nose knows long before the doctor does.
