A team of Swedish researchers suggests that humans are able to smell sickness in other people, or at least smell when their immune system has gone on overdrive to fight out infections.
The study was conducted by researchers at Karolinska Institute, in Sweden, who recruited 8 healthy individuals and randomly gave them either a saline injection or lipopolysaccharide (LPS), a toxin known to ramp up an immune response.
They were then made to wear tight t-shirts that were designed to absorb sweat over the next four hours. Participants who had been injected with LPS displayed elevated body temperatures and increased levels of cytokines, a group of immune system molecules. The t-shirts were then given to a separate group of 40 individuals to smell the sweat samples and the researchers found that majority of the participants of the second group said that the t-shirts from the LPS group had a more intense, unpleasant and unhealthy smell compared to the saline group.
"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", lead researcher Professor Mats Olsson said.