A Tasteless Virus – COVID and Taste Perception

What’s the point of having a variety of foods if we have lost our perception of taste? In a tasteless world grocery stores would provide options based solely on texture and nutrition. Our ability to have mouth feel would still be there and so would the preference for different textures. In a tasteless world, leaving out the spice aisle along with the sauce wouldn’t cause much dismay. 

While quarantined with COVID I experienced tastelessness. Taste relies on the olfactory system just as much as our taste buds. I was not alone as 40-60% of people with COVID experienced olfactory disruption along with 38-50% having gustatory problems (https://www.frontiersin.org/articles/10.3389/fcimb.2021.716563/full). It was a strange experience. I didn’t indulge in uber eats because eating was far from being uber. Instead, I opted for plain foods which serviced my body solely for nutrition. The experience was strange because I knew what these foods should taste like, however, I was unable to taste them. I even tried to imagine while I was eating what they would taste like if I didn’t have the virus. It was a case taste memory being at odds with current experience. The same food should produce the same taste perception, and this is important to establish a memory of taste preferences and aversions. In a state of tastelessness, however, what you used to enjoy doesn’t matter. I could’ve eaten fermented shrimp paste without making the “EW” face, but with the aches and pains I wasn’t feeling that adventurous. 

Tasting Domino’s 

Taste is a complicated biological process. Even more so is the experience of finding your next meal and eating. Perceiving taste relies on taste buds composed of many cylindrical “taste” cells. Given the different kinds of taste, we need different types of cells to perceive. A salty taste is recognized by one type of cell whereas something sweet may be recognized by a different subset of cells. The current research subscribes to this paradigm where one flavour may be recognized by one type of cell where others are recognized by a subset of cells. A Michelin starred meal is said to have the right flavour balance of the big 5: sweet, sour, bitter, salty, and umami. You may strive for the same at home but may never reach that level. Nevertheless, perceiving tasty meals rely on a complicated interplay of these cells being activated. When I say activated, I am referring to the specific receptors, likely bound to the surface of these cells. These receptors, termed G-protein coupled receptors, are responsible for perceiving sweet, umami, and bitter tastes. Salty and sour tastes relegated to receptors coupled to ion channels – a more direct line to firing neurons which translates to perception. Sometimes salty or sour foods cause one to salivate before eating it and maybe this direct connection to an action potential is the reason why. In humans, the other mechanism via G-protein coupled receptors (GCPRs) are more understood. These receptors are like sense organs for “taste” cells and bind to molecules like sugar or sweeteners. When this happens, the receptor is activated and the signal, like toppling dominos, is passed on and eventually ends up travelling through the nervous system. The act of sense perception in a complex human or a relatively simple amoeba is the same: signalling > signalling domino effect > perception > response, and if your home cook meal lives up to the ambitions of Gordon Ramsay, the response will be a resounding “mmm!” 

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