Your breath may indicate if you have liver disease or diabetes (Picture: Getty)
Have you ever been paranoid that you smell?
Well, you do – but not in the way you think.
The human body releases hundreds of chemical streams from our bodies into the air every day, but they’re giving away much more than just our personal hygiene routine.
They are giving off health indicators about our bodies.
The Greeks did it first (of course) when Hippocrates used the ‘art of smell’ to diagnose diseases, in a concept known as the Miasma theory.
The theory, that smells can cause illness, has long since been abandoned, but really it just had things upside down – because scents from the body can help diagnose disease.
In 1971, Nobel Laureate chemist Linus Pauling counted 250 different gaseous chemicals in our breath, known as volatile organic compounds (VOCs), which originate from millions of skin glands removing metabolic waste from the body.
The Miasma Theory
It was thought that epidemics were caused by bad air from rotting organic matter
The theory formed the basis of the plague mask, where pleasant-smelling organic matter was placed at the end of the beak to stop the bad air from spreading the plague
The theory was replaced by the germ theory in the 1800s after the theory was first challenged by John Snow (developer of anesthesia and medical hygiene) and confirmed by Robert Koch (a German microbiologist who discovered the cause of deadly infectious diseases)
The Miasma theory has been widely used in popular culture, especially in anime
Professor Aoife Morrin, from Dublin City University, says: ‘VOCs from skin are the result of millions of skin glands removing metabolic waste from the body, as well as waste generated by bacteria and other microbes that live on our skin.
‘Sweating produces extra nutrients for these bacteria to metabolise which can result in particularly odorous VOCs. Odour from sweat only makes up a fraction of the scents from VOCs though.’
These VOCs can give away more you think.
For example, when your breath has a strong musty smell, it could be a sign that your liver is not filtering out toxic substances as it should – which is known as fetor hepaticus.
Another well-known example is sweet-smelling breath, which could signify diabetes.
Dogs are able to smell certain cancers off people (Picture: Getty Images/iStockphoto)
As well as our breath, these VOCs also come from our skin, urine and faeces.
In one case, a woman noticed her husband began to smell differently 12 years before he developed Parkinson’s.
Nicknamed ‘the woman who can smell Parkinson’s’, Joy Milne and her hypersensitive senses helped scientists develop a simple swab test to help diagnose the condition.
But it’s not just humans who can sniff out disease.
Animals with more sophisticated olfactory abilities such as dogs have shown they can detect various types of cancer in humans such as colon cancer, prostate cancer, breast cancer, and melanoma.
Although rarely detectable by the human nose, the cases provide evidence that humans emit different scents when there is something up with the body.
Can you sniff out a Valentine?
Professor Morrin says: ‘In the animal kingdom, there is good evidence VOCs can act as aphrodisiacs. Mice for example have microbes which contribute to a particularly smelly compound called trimethylamine, which allows mice to verify the species of a potential mate. Pigs and elephants have sex pheromones too.
‘It is possible that humans also produce VOCs for attracting the perfect mate.
‘Scientists have yet to fully decode skin – or other – VOCs that are released from our bodies.
‘But evidence for human love pheromones so far is controversial at best. One theory suggests that they were lost about 23 million years ago when primates developed full colour vision and started relying on their enhanced vision to choose a mate.’
However, the exact relationship between VOCs, bacteria and our health is still being studied, in a bid to maintain our health and alert us to any diseases.
Professor Morrin and her team are looking into whether the skin VOC signature can reveal different attributes of the person it belongs to, with the ability to already predict a person’s age with reasonable accuracy to within a few years from their skin VOC profile.
Writing for The Conversation, she said: ‘We are at a relatively early stage in this research area, but we have shown that you can tell males from females based on how acidic the VOCs from skin are.
‘We believe skin VOCs can reveal who and how we are, in terms of things like ageing, nutrition and fitness, fertility and even stress levels. This signature probably contains markers we can use to monitor our health and diagnose disease.’
So who nose (sorry), maybe one day we will be able to detect diseases by just breathing into a device.