Can taste be affected in MS?


1 February 2016

The study in brief

Problems with taste and smell are thought to be extremely rare symptoms in MS, but as they are interconnected it can be difficult to study each of them individually.

This study aimed to investigate taste in people with MS to work out how common problems with taste are. 73 people with MS and 73 control participants matched for age, gender, ethnicity and education level took part. Each participant took part in the taste test where the researchers placed a small amount of liquid containing a sweet, salty, sour or bitter ingredient on to part of the tongue of each participant. The participant then had to identify what type of taste it was and also how intense they perceived the taste to be.

The study found that participants with MS had more problem identifying tastes when compared to the control participants. Participants with MS rated the intensity of the bitter taste lower than control participants, but were still able to rate the intensity of the other tastes appropriately. Suggesting MS has a stronger effect on the ability to taste and identify what it is, rather than how strong the taste is.

This study demonstrates that more people with MS could have problems with taste than previously thought.

The study in detail

Background

Our sense of taste is really important to us. It protects us from eating something that is dangerous or unsafe. Our tongues are covered in thousands of little bumps which are taste buds, these recognise five main tastes: sweet, sour, bitter, salty and umami (which can be described as a savoury taste). Women tend to have more taste buds than men. Taste is closely related to smell, your tongue can identify the five main types of taste but your nose is more sensitive that the taste buds and can distinguish many hundreds of substances, even in very small amounts. Both taste and smell work together so you can experience flavours, if you have had a cold you will know you can temporarily lose your sense of smell and whatever you eat tastes really bland.

Problems with taste and smell are thought to be extremely rare symptoms in MS, but as they are interconnected it can be difficult to study each of them individually.

This study investigated taste in people with MS and aimed to work out how common problems with taste are, how severe they are, if MS only affected the recognising of particular types of taste and if problems with taste could be matched with locations of brain lesions.

How this study was carried out

73 people with MS and 73 control participants matched for age, gender, ethnicity and education level took part in this study. This study was part of a larger study looking at the senses (including taste, hearing, smell) in people with MS.

Each participant took part in the taste test. The researchers tested four of the main taste types using:

  • sucrose – a type of sugar (sweet)
  • sodium chloride – the main component of table salt (salt)
  • citric acid – the type of acid commonly found in citrus fruits such as lemons (sour)
  • caffeine – commonly found in tea and coffee (bitter)

The researchers placed a small amount of liquid containing one of these ingredients on to part of the tongue of each participant. The participant then had to identify what type of taste it was and also how intense they perceived the taste to be.

Each participant took part in 96 taste tests. The four different ingredients were tested six times on each part of the tongue. There were four regions on the tongue tested: front left, front right, back left and back right.

Usually on the same day as the taste testing, participants with MS also underwent MRI brain scanning using gadolinium enhancement.

What was found

The study found that participants with MS had more problem identifying tastes when compared to the control participants. Of the participants with MS 15% had difficulty identifying the bitter taste, 22% the sour taste, 25% the sweet taste and 32% the salty taste. Those participants who had more trouble identifying tastes also had a larger volume of lesions as seen on MRI brain scans.

Participants with MS rated the intensity of the bitter taste lower than control participants, but were still able to rate the intensity of the other tastes appropriately. Suggesting MS has a stronger effect on the ability to taste and identify what it is, rather than how strong the taste is.

Overall in both the MS and control groups, women were better at identifying the tastes and also rated them as more intense than men, this is probably because women have more taste buds.

What does it mean?

This study demonstrates that more people with MS could have problems with taste than previously thought. The researchers found that MS was commonly associated with trouble identifying the four classic taste qualities. Although women with MS, like women in general, were able to identify more tastes accurately than men.

The authors highlight the importance of be able to taste. If you cannot taste food properly you could potentially eat something unsafe and you may not enjoy your food if it does not taste ‘right’. This could potentially mean people cut certain foods out of their diet which could lead to malnutrition, a common condition that occurs when the diet does not contain the right amount or balance of nutrients for health.

Doty RL, Tourbier IA, Pham DL, et al.
Taste dysfunction in multiple sclerosis.
J Neurol. 2016 Jan 25. [Epub ahead of print]

More about diet

Eating a healthy, balanced diet is an important part of maintaining good general health.

Research into diet and MS has been limited. However, there has been research into a healthy diet for other conditions, which found that a diet that was low in fat, with lots of fruit and vegetables reduced someone's risk of developing heart disease, strokes and certain cancers. Consequently this forms the basis for the Government's advice for a healthy balanced diet. A balanced diet is essential to provide all the nutrients needed to be as active and healthy as possible. This includes foods from the major food groups of fruit and vegetables, carbohydrates, fat, protein and dairy products.

The role of diet in helping people with MS with problems such as eating difficulties, bladder problems and constipation, is now generally accepted. A poor diet and nutrition can also worsen existing symptoms such as fatigue and weakness.

However some symptoms can also make consuming a balanced diet more difficult. Mobility problems may make it more difficult to go to the shops and buy a variety of fresh food or move around the kitchen preparing a meal. Fatigue may mean the person is exhausted just preparing the meal and so doesn't eat it. As this study shows problems with taste could also be a symptom of MS and so eating a variety of nutritious food may be difficult as certain food may not taste as they should and may not be enjoyable or pleasant to eat.

If you are concerned about changes in your taste or are struggling to eat a balanced diet due to other symptoms, you could speak to your MS specialist team or GP. They may be able to help directly or may refer you to specialist support, such as from a dietitian or speech and language therapist.

You can read more about diet in the A to Z of MS.

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