Normally, most individual variation in the sensitivity to smell and taste lies within the normal biological range. However, a low sensitivity to taste or smell becomes a problem if it affects your health and/or well-being.

In The Netherlands, an estimated number of 250.000-300.000 people suffer from smell and/or taste disorders. Taste and smell dysfunctions can be inborn or due to trauma, disease or medicine use. For example, certain medication affects saliva production or epithelial cells in the oral cavity. It may also be that brain trauma causes taste phantom sensations, these are sensations while the actual stimulus is not present. An example are patients with Burning Mouth Sensations, these people experience very intense somatosensations  (i.e., touch, temperature, pain/burn) without the stimulus being present.

Another well-known example of a condition affecting smell and taste is COVID-19. The loss of smell and taste is even recognized one of the diagnostic criteria for infection with the virus. How COVID-19 changes taste and smell exactly, remains unknown. The virus seems to affect cells supporting the olfactory nerve. This can block the signals going from this nerve through the brain, causing loss in smell (and taste through the loss of smell).

See this link for more information about the treatment of taste and smell disorders.

Smell and taste Centre

Studying clinical taste and smell disorders tells us more about how the sensory systems work on a neurological level. In the Smell and Taste Centre, a joined force from Wageningen University and Hospital Gelderse Vallei, people with taste and smell loss undergo intensive protocols to further unravel these disorders. Olfactometers and gustometers are machines that are used in this research to deliver specific odors and tastes in a controlled manner to patients. Simultaneously, brain responses can be measured using fMRI and EEG, to identify the underlying causes for taste and smell loss.

In the short video below, Dr. Elbrich Postma tells you more about smell and taste loss in her talk “How to taste with your nose”