It’s that time of the year again when we get colds and the flu. Often when we get sick with flu we don’t taste what we eat and drink. Why does this happen? Our taste and smell are closely entwined. Our noses, believe it or not, play a big role in what flavours the tongue can identify, and when the nose is blocked because of flu and the nasal cavity becomes congested with mucus it tends to make the food tasteless.
The nose and the mouth are connected by the nasal and oral cavities running into each other. That is why when the cavities are full of mucus when you have the flu it nullifies the different flavours of food.
Receptor cells in the mouth and the nose
Our tongues have thousands of taste buds and they help us to identify the four different primary tastes – salty, sweet, sour and bitter, while the olfactory receptor cells in the nasal cavity measures the odours that provide the great flavours in our food. When these cells are stimulated they send out signals to certain areas of the brain that make us aware of the perception of taste. So the messages that process our taste and smell converge giving us an all round idea of what we consume.
When we eat our taste buds detect tastants that are the chemicals in the food. There are between 5,000 to 10,000 taste buds on every persons tongue. With each taste bud consisting of 50 to 100 specialised sensory cells, which awakens when the tastants in the food such as salts, sugars or acids are detected.
Mucus membranes that line the roof of the nose have specialized sensory neurons that identify odorants or odour molecules. To get the savoury or not so savoury flavours – the odorants get stimulated by the chemicals or smells in food, which initiates a pattern sent to the olfactory bulb. After passing the primary olfactory which is situated in the frontal lobe in the brain, the message is then carried to the adjacent parts of the orbital cortex where the perception of flavour is created, through the combination of odour and tastes.
When your nasal passages are blocked with thick mucus caused by the flu, the molecules from the air and the food won’t be able to reach your olfactory receptor cells. In other words your brain will not be able to receive the signal that identifies the odour, and then everything you eat tastes the same. However, you will still be able to feel texture and the temperature of the food because this information is processed on the tongue.
Post nasal drip can also cause a lack of taste. Post nasal drip is a condition where the mucus drips down the back of your throat instead of out your nose. Post nasal drip is caused when you have a cold, the flu or have nasal allergies. All of these contribute to wiping the flavour from foods.
So in a nutshell, what causes your inability to taste food when you have the flu is all related to the sniffling. Our taste and smells are the perception of the chemicals in the air or in the food we eat. So next time you have the flu and your food tastes like cardboard, remember not to blame your taste buds, put the blame on your clogged up nose.