Detecting sickness by smell

Humans are able to smell sickness in someone whose immune system is highly active within just a few hours of exposure to a toxin, according to new research published in Psychological Science, a journal of the Association for Psychological Science.

According to researcher Mats Olsson of Karolinska Institutet in Sweden, there is anecdotal and scientific evidence suggesting that diseases have particular smells. People with diabetes, for example, are sometimes reported to have breath that smells like rotten apples or acetone.

Being able to detect these smells would represent a critical adaptation that would allow us to avoid potentially dangerous illnesses. Olsson wondered whether such an adaptation might exist already at an early stage of the disease.

"There may be early, possibly generic, biomarkers for illness in the form of volatile substances coming from the body," explains Olsson.

To test this hypothesis, Olsson and his team had eight healthy people visit the laboratory to be injected with either lipopolysaccharide (LPS)—a toxin known to ramp up an immune response—or a saline solution. The volunteers wore tight t-shirts to absorb sweat over the course of 4 hours.

Importantly, participants injected with LPS did produce a noticeable immune response, as evidenced by elevated body temperatures and increased levels of a group of immune system molecules known as cytokines.

A separate group of 40 participants were instructed to smell the sweat samples. Overall, they rated t-shirts from the LPS group as having a more intense and unpleasant smell than the other t-shirts; they also rated the LPS shirt as having an unhealthier smell.

The association between and smell was accounted for, at least in part, by the level of cytokines present in the LPS-exposed blood. That is, the greater a participant's , the more unpleasant their sweat smelled.

Interestingly, in a chemical assay the researchers found no difference in the overall amount of odorous compounds between the LPS and control group. This suggests that there must have been a detectable difference in the composition of those compounds instead.

While the precise chemical compounds have yet to be identified, the fact we give off some kind of aversive signal shortly after the has been activated is an important finding, the researchers argue. It grants us a better understanding of the social cues of sickness, and might also open up doors for understanding how infectious diseases can be contained.

More information: pss.sagepub.com/content/early/… 97613515681.abstract

Related Stories

Team finds molecule that triggers septic shock

Sep 12, 2013

The body's immune system is set up much like a home security system; it has sensors on the outside of cells that act like motion detectors—floodlights—that click on when there's an intruder rustling in ...

Explainer: What is the immune system?

Jan 08, 2014

The immune system is an integral part of our body, keeping us safe from diseases – from the common cold to more severe illnesses such as cancer.

Recommended for you

Research shows seven-year-olds can think strategically

8 minutes ago

(Medical Xpress)—A study by Melissa Koenig of the University of Minnesota and colleagues shows that by the time they reach the age of seven, children can think strategically, in an adult manner. The researchers ...

Discovery hints at why stress is more devastating for some

4 hours ago

Some people take stress in stride; others are done in by it. New research at Rockefeller University has identified the molecular mechanisms of this so-called stress gap in mice with very similar genetic backgrounds—a ...

Family dinners reduce effects of cyberbullying in adolescents

16 hours ago

Sharing regular family meals with children may help protect them from the effects of cyberbullying, according to a study by McGill professor Frank Elgar, Institute for Health and Social Policy. Because family meal times represent ...

The Edwardians were also fans of brain training

22 hours ago

Brain-training programmes are all the rage. They are part of a growing digital brain-health industry that earned more than US$1 billion in revenue in 2012 and is estimated to reach US$6 billion by 2020. The extent to which they actually improve brain function re ...

Report advocates improved police training

Aug 29, 2014

A new report released yesterday by the Mental Health Commission of Canada identifies ways to improve the mental health training and education that police personnel receive.

User comments