Why do lazy things smell bad

People recognize diseases by their smell - they pay too little attention to it

Such abilities leave us amazed, but basically every person with a functioning sense of smell could learn to recognize various disease odors. People are very good at detecting disease, says Valerie Curtis, a health care researcher at the London School of Hygiene and Tropical Medicine.

"Signs of illness are one of the things that people find grossest," says Curtis. These include, for example, mucus, vomit, and pus. Disgust is our way of avoiding things that could harm us. "It just makes evolutionary sense that we use our noses to notice diseases." (Worth reading: Those who are disgusted by these images may suffer from trypophobia)

But why do sick people smell differently at all? Our bodies are constantly releasing volatile chemical compounds into the environment. They are in our breath and literally come out of every pore. These substances vary according to age, diet and health status. The microbes that live in our intestines and on our skin also influence our body odor by breaking down our metabolic products.

Basically, you're an odor factory on legs. And once you start paying attention to body odors, you may notice changes.

This is not a patchouli

Recently, the case of a woman who can smell Parkinson's has brought back attention to the idea of ​​disease sniffing. Parkinson's is notorious for being extremely difficult to detect early. Most people have already lost half of the dopamine-producing brain cells that fall victim to this disease by the time they are diagnosed. About six years before her husband was diagnosed with Parkinson's disease, Joy Milne noticed that he smelled strange.

Les had "a kind of woody, musky smell," as Milne told the Telegraph. Years later, in a room full of Parkinson's patients, she noticed that it wasn't just Les who had that smell. All Parkinson's patients smelled like that.

She mentioned this to Tilo Kunath, a Parkinson's researcher in Edinburgh, who in turn told his colleague Perdita Barran, a chemist. They decided that the well-meaning Mrs. Milne must have smelled the characteristic smell of old people. "We talked ourselves out of it," says Barran.

And that's where the story could have ended. But another biochemist encouraged the duo to track down Milne and do a t-shirt blind test with her: she smelled sweaty T-shirts from people diagnosed with Parkinson's and six shirts from a healthy control group. Milne correctly identified all six Parkinson's disease patients by the smell of their shirts, but also stated that a healthy patient's shirt had Parkinson's disease.

Despite the mistake, Barran was intrigued - all the more so when she learned about eight months later that the supposedly healthy person whom Milne had indicated to be sick in the olfactory test had been diagnosed with Parkinson's disease.

The smell test

The t-shirt test was exciting, but one to be treated with caution. After all, there are a ton of reasons why some people's smells are similar.

In the late 1960s, researchers became convinced that there was a certain smell associated with schizophrenia - a fatty acid called TMHA. The compound, which allegedly smelled of goat, was identified and described in the renowned specialist magazine "Science". It was even hoped that this connection was the cause of schizophrenia, which would open up new treatment options.

But in the following years the results could never be confirmed in further experiments. Thus the TMHA theory disappeared from the table again.

Barran is now working at the Manchester Institute of Biotechnology, trying to identify Parkinson's odor using biochemical methods. She and her colleagues want to develop an odor test for Parkinson's - a more precise and practical one than letting Mrs. Milne smell T-shirts.

How do diseases smell?