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December 11, 2020

The science behind parosmia

Investigating the flavour compounds that trigger parosmia

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Barry Smith, Simon Gane and Jane Parker covered so much of interest when we brought them together in our 10 November webinar on Parosmia. We couldn’t resist digging a bit deeper into Jane’s work.

Flavour chemistry

Dr Jane Parker is an Associate Professor of Flavour Chemistry at the University of Reading and long before Covid brought parosmia into the limelight, her work has been in understanding the molecules within flavours.

In the laboratory, Jane and her team put people through a series of tests to assess their ability to smell, looking at aspects like the strength of smell and picking out different smells. Over the last few months they have adapted their tests to try and understand more about the parosmia experienced by recovering Covid patients.

One of the biggest challenges in Jane’s work is getting people to describe smell. Parosmic smells in particular are very difficult to find words for. ‘Rubbery’ ‘cigarette smoky’ ‘sickly sweet’ are common descriptions from which Jane is starting to build a picture of different types or groups.

What is emerging quite clearly is that compounds that contain sulphur or nitrogen are key triggers. Smells including coffee, meat and peanuts contain molecules of sulphur among the hundreds of other chemical compounds that make up their individual smell pattern. When parosmia disrupts the pattern it’s the unpleasant sulphur compounds that poke through.

Another common trigger is food that is baked, roasted, toasted or grilled. Here it’s nitrogen that seems to be the common culprit.

What can we do about it

Although not everyone with parosmia reacted to the same triggers, the researchers have been able to identify ‘families’ of compounds that may trigger parosmia. This could lead us both to a greater understanding of what has changed within our olfactory systems, and also to the creation of a useful guide on foods and smells to avoid if you’re sensitive to a particular ‘family’.

Understanding what triggers parosmia for you can help you avoid those situations where you know you will be overwhelmed by smells. Interestingly though, the panel were in general agreement that longer term, avoiding those triggers might not be the best solution. Patients who keep exposing themselves to known triggers and keep experimenting seem to be more likely to get over parosmia more quickly.

You can watch the whole fascinating discussion - including the panel's thoughts about poo - on our YouTube channel