Causes of ageusia or loss of sense of taste

“They didn’t turn out very well, these torries don’t look like anything else! They’re doughy and earthy!” – Martha commented in the kitchen of her house. The truth is that the dessert was delicious as always, but after contracting Covid-19 he became ill. ageusia. That is, he could not taste the food. Despite this, he found the texture of torrija, a pasty dough coated with cinnamon powder and sugar crystals, that his brain found unpleasant.

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To her surprise, Martha was not alone: ​​throughout 2020 and 2021, a large number of people around the world suffered to a greater or lesser extent from the same symptoms that she described in the kitchen of her home.

Ageusia or loss of taste is neurological symptom in which, as a rule, the neurons responsible for transmitting signals from taste buds to the brain stop working correctly. Although there are people who suffer from it from birth, this symptomatology has become especially relevant after the increase in the number of cases of ageusia caused by Viral infection COVID-19.

There has now been progress in knowledge about the mechanisms underlying this symptom, but some questions still remain unanswered. Therefore, to understand why ageusia occurs, the first thing you need to do is understand what is taste

I like it

To imagine taste bud It’s best to think of an orange. If we peel an orange, we will see that it has different segments and a slit in the middle. In the taste bud, several neurons combine to form “segments” of orange and form a lump on the tongue with a small funnel-shaped hole in the middle. The taste bud funnel, called taste timefilled with a special liquid in which the chemicals of everything that enters our mouth can diffuse.

Once inside the pores, the chemicals activate recipients located in the membrane of the nerve cell. These receptors are specially prepared to transmit messages almost instantly into the cell. Depending on the message they send, the cell will understand that it is moving from one food to another and will release specific neurochemicals brain to tell it what food tastes like. Thanks to these little miracles of evolution, humans can distinguish the taste of food almost in real time.

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But not everything happens on the tongue; our perception of taste also depends on smell, texture and even temperature the foods we eat. These features help us add nuance to food and distinguish between two tastes that may be very similar. Moreover, among the products that seem “good” and “bad” to us, there is also a very important psychological component associated with the experience. Now, when certain substances or viruses damage any component of this complex system, our perception of taste can change.

Food is like nothing else to me.

One of the most characteristic symptoms of COVID-19 was Partial or complete loss of smell and taste. This symptom, which caught many patients by surprise, usually persisted for weeks or months after infection, causing concern among doctors and researchers. This concern arose because the cells inside taste and smell receptors are nerve cells, so if the virus was able to damage them, that meant it could also damage other parts of the nervous system.

Tests on this are currently needed, but research suggests that the cause of ageusia and anosmia (loss of smell) will be the death of both the olfactory tissue and the taste receptor neurons. However, this death does not occur because the virus directly infects neurons, but rather This will destroy the cells that are responsible for their nutrition and protection. Without these support cells, the neurons eventually die and stop sending taste signals to the brain, depriving patients of this sense.

But it is worth remembering that COVID-19 is not the only cause of ageusia, but rather With age, taste is lost. After age 60, taste buds begin to decline, especially those that detect sweet and salty. It has even been reported that in very old age the taste may disappear completely.

In addition, some respiratory diseases such as cold or flu They can also greatly influence the perception of taste, and there have been cases from brain injury or surgery this eventually led to permanent ageusia. However, it is worth emphasizing that this rare diseasewhich is most common for preserving the sense of taste throughout life.

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Debunking the myth of taste

Diverging slightly from the main topic, we have all seen a typical picture at one time or another. color image of tongue in which zones that capture certain aromas are divided. This image is called a taste map and typically indicates that sweetness is experienced at the tip, bitterness at the back, and sourness and saltiness at the sides. Unfortunately the image misinterpretation of the study more than a century ago. The reality is that no, the tongue is not divided into “zones” that capture specific tastes, the entire tongue is capable of capturing all tastes, albeit with a huge “but”.

If this There are areas of the tongue with greater sensitivity to a particular taste. as a seminal 1901 paper by German psychologist David Hanig showed. Although the reason for these differences is still not exactly known, it has been observed that there are a huge number of factors that influence taste detection, such as person’s gender, age (as we already mentioned), suffer from autoimmune diseasesor your exposure to certain substances such as tobacco.