Taste and smell are separate senses with their own receptor organs, yet they are intimately entwined. Taste is detected by the taste buds which, when stimulated in certain ways, send signals to specific areas of the brain.
Similarly, specialised cells in the nose transmit certain messages when they pick up odorants. These messages about taste and smell converge, allowing us to detect the flavours of food.
As anyone with a head cold will tell you, food ‘tastes’ different when the sense of smell is impaired. That’s because only the taste, and not the food odours, are being detected.
So, when your sense of smell goes south, taste usually follows. Here are a few things that can cause loss of taste and smell.
As you age, your taste buds decline in number; the 10,000 you are born with start decreasing once you hit middle age. The taste buds that you’re left with may shrink and become less sensitive, making it harder to perceive taste.
Salty and sweet flavours tend to weaken first, often causing people to add more salt and sugar to their meals. Later, it may be more difficult for you to taste things that are bitter or sour.
You can’t reverse age-related loss of taste but don’t assume it’s just a side-effect of ageing – speak to your GP to ensure there’s no other cause.
Your sense of smell can also weaken with age.
Illness or infection
Anything that irritates and inflames the inner lining of your nose and makes it feel stuffy, runny, itchy, or drippy can affect your sense of smell and/or taste. This includes the common cold, sinus infections, allergies, sneezing, congestion, the flu, and COVID-19. In most cases, your senses will return to normal when you feel better.
Read more: Losing sense of smell to coronavirus
Your sense of smell can be thwarted if you physically can’t pull enough air through your nose when you inhale. This can be caused by blockages such as nasal polyps or a deviated septum.
In some people, a change in taste or smell can be an early sign of Alzheimer’s or Parkinson’s. Certain medical conditions can affect the parts of your brain responsible for receiving smell and taste information. Nerve damage can be caused by conditions such as diabetes, Bell’s palsy, Huntington’s disease, Klinefelter syndrome.
Cancer and treatment
Cancer treatments can change the messages sent between your sensory cells and your brain, causing muted sensations or unexpected ones. For example, chemotherapy can cause the patient to have a metallic taste in their mouth and make certain smells seem stronger or different. These issues often disappear when treatment ends.
Cancerous tumours in the head and neck can also cause sensory loss.
Some prescription and over the counter medications can wreak havoc on your senses. The most common medications that affect taste are angiotensin-converting enzyme inhibitors, which are used to treat high blood pressure.
Other medications can alter your taste buds, scramble the messages sent and received or change your saliva.
Another common way medication affects taste is by contributing to dry mouth, which makes it hard for the taste buds to recognise taste chemicals.
Some common medications that cause dry mouth are:
- CNS medications
- muscle relaxants
- thyroid medications
Read more: Are you losing your senses?
A loss of taste and smell could be the way your body is telling you you’re low in something. Certain vitamins and minerals are necessary for taste buds to function properly.
Deficiencies in the following nutrients may lead to a loss of taste:
- vitamin A
- vitamin B6
- vitamin B12
The dangerous chemicals in cigarettes, such as carcinogens and alkaloids, can injure or kill the receptors attached to your taste buds.
In one study, researchers explored changes in the perception of taste in smokers who quit smoking. Initially, a high nicotine dependence correlated with a lower taste sensitivity in study participants. As the study period progressed, the researcher observed improvements in taste-bud function in as little as two weeks.
Trauma to the head, neck or brain can damage your olfactory nerve, which carries scent information to the brain. Damage to the lining of your nose, nasal passages of parts of the brain that process smell can also cause a shift in the sense. It may be immediately obvious after a head injury or can come on over time. In some mild cases, the sense may return on its own. If the trauma was more severe, you may partly recover and only be able to taste and smell very strong flavours and scents.
Read more: Poor smell linked to dementia risk
A sudden change in your taste buds or a sudden loss of taste can indicate an underlying medical condition but most causes, such as the common cold, can be treated at home.
However, in some situations, certain viral or bacterial illnesses can overwhelm the immune system. If you are having trouble eating, drinking, or breathing, you should seek medical attention right away.
Have you noticed a change in your sense of smell or taste as you age? Why not share your favourite scent in the comments section below?
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Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.