Understanding taste disorders

Taste disorders are conditions that can manifest as a reduced ability to taste, distorted taste sensations, or even a complete loss of taste. These disorders can significantly impact quality of life, affecting not only the enjoyment of food but also health and nutrition.

Professor Carl Philpott, renowned ear, nose and throat specialist, provides an expert insight into taste disorders, exploring the different types, their causes and symptoms, as well as the available treatments.

What are the different types of taste disorders? What's the most common one?

From a medical perspective, when we talk about taste, we are referring to the sense responsible for detecting salt, sweet, sour, bitter, and umami, (which is a savoury sensation), that are experienced through the tongue and other receptors inside the mouth. This sense is separate from the sense of smell. Disorders of smell affect the pathways that begin in the nose and go upwards to the brain.

When we’re eating food, we smell and taste together, and so a lot of people who experience loss of smell believe they’re experiencing loss of taste when, in fact, their sense of taste is actually fine.

So, true taste disorders are actually a rare entity. They probably account for only 1-2% of all cases we see in our smell and taste clinic when testing is conducted. Roughly speaking, they can be divided into two groups:

• Loss of taste, which refers to the reduced ability to perceive the five basic tastes.
• Disturbances of taste, where you experience distortions in taste, such as a persistent salty sensation in the mouth.

Overall, these can be caused by a number of different things. We don’t always identify a cause in a lot of the cases we encounter, but common causes for disturbances include medications that cause side effects that affect taste. Certain mineral and vitamin deficiencies are also associated with taste disorders.

Additionally, some blood disorders such as anaemia can contribute, and occasionally, autoimmune conditions may also play a role. 

The other group of patients we see with taste disorders are those who are affected following surgery, typically operations in the ear, nose, and throat area. For example, the taste nerve that supplies the front part of the tongue can be cut during ear surgery, and sometimes this is a necessary step in order to access the problem within the ear.

Operations in the mouth, such as the removal of the tonsils or a procedure known as a microlaryngoscopy, where the voice box is examined under anaesthetic, can affect some of the other nerves that supply taste sensation to the back parts of the tongue and mouth.

Furthermore, other causes are dental surgery and surgery in the neck that affects the lingual nerve, which again is the part of the pathway that supplies taste to the front part of the tongue.

Can taste disorders be sudden? What are the other symptoms?

Whether they occur suddenly will depend on the cause.

For instance, with ear surgery, if the nerve is cut during the procedure, you would suddenly notice the difference upon waking up from that. If the ear surgery is only on one side, that usually resolves itself over the coming weeks, because the other side of the tongue compensates, so you typically wouldn’t notice any persistent changes.

If medication is the cause, for instance, then it’s more likely to be a gradual process as the medication takes effect, but this can vary from person to person. Additionally, the timing of the onset in relation to starting the medication may be a critical factor in making the diagnosis.

In terms of other symptoms, smell and taste disturbances often go together. Usually, because people mistake loss of smell for loss of taste, and that’s partly due to our language; we often talk about tasting food when, actually, a lot of what we’re doing is smelling the aroma of food when it's inside our mouth.

For example, in patients who have suffered a head injury, if the injury has affected the parts of the brain where smell and taste are received, then you could actually experience loss of smell and taste of sudden onset, carrying around from the head injury. This may occur in the aftermath of the incident, with the symptoms occurring together at the same time.

What conditions cause them?

A large group of taste disorders that I see in practice tend to have no identifiable cause, which we refer to as idiopathic.

Regardless, it’s important for us to understand any detail in the patient's medical history that may have contributed to this condition. As I mentioned before, this includes head injuries, any previous surgery in the head and neck area, existing medical conditions such as autoimmune disorders and anaemia, as well as any other relevant medical factors.

For the cases where we believe we can’t find an identifiable cause from the history, we go through a careful process of testing the patients’ sense of taste and also conducting tests to look for rare causes. This can involve a series of blood tests and possibly an MRI, which will help us see if there are any underlying issues.

How are taste disorders treated?

This will again depend very much on the cause. If there is a cause in itself that can be treated, such as if medication is causing the problem, then trying to stop the medication will usually help. Similarly, if if the cause is anaemia, then treating the anaemia may be helpful.

If the taste disorder has been caused by a head injury, then obviously managing the head injury as a whole becomes the relevant issue, and treatment will depend on the severity of the injury. In certain circumstances, particularly with distortions of taste, treating the distortion itself may be helpful.

Sometimes, using a supplement known as Zinc Gluconate can be helpful for true taste disorders. Additionally, modifying distorted signals with medications such as Amitriptyline and Gabapentin can help patients with marked disturbances of taste.

Are there ways to manage taste disorders alongside medication?

Yes, absolutely, and a good place to find non-medical support is through our charity's website (Fifth Sense), where you will find a range of support, particularly for people with true taste disorders.

One of the key aspects of support often relates to food. So, if the sense of smell is preserved and true taste is lost, then there may be ways to enhance enjoyment through the smell side of food, as well as through texture and temperature changes. Therefore, you will typically still retain the preservation of function, regarding the ability to sense spiciness and the hot and cold aspects of food.

If you would like to book an appointment with Professor Carl Philpott, head on over to his Top Doctors profile today.