Taste and smell changes

Sunday 12 July, 2015

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  On this page: How do we experience flavour? | Why are the senses affected? | The importance of a healthy diet | What changes could I experience? | How long do changes last? | What is the solution?  


This information has been prepared to help you understand more about the possible effects of cancer treatments on your experience of eating. Some treatments can change the taste or smell of food, or the feeling of food in your mouth.

Up to 80% of people receiving cancer treatment report changes in the flavour of food. These can affect the way they enjoy food, and could lead to a less nutritious diet. 

How do we experience flavour?

Three senses work together to enable you to experience flavour. These are taste, smell and touch (the way food feels in your mouth), and they can change as a result of cancer treatment. 

Other factors such as your emotions or the place where you eat (e.g. the hospital) can influence the way you experience flavour and your enjoyment of food. Changes in appetite and food enjoyment, while not changing the actual taste or smell of food, can result in the flavour no longer being experienced as pleasant. 

The sense of taste

Taste is experienced when food or drink, mixed with saliva, reaches tastebuds located all over the tongue and inside the mouth. Tastebuds detect five basic tastes: sweet, salty, sour, bitter, and savoury (umami). These tastes are the building blocks of flavour, and they combine with the senses of smell and touch to give rise to many flavours.  

The sense of smell

Smell is experienced when odour particles are detected in the air and enter the nose either through the nostrils or the mouth. Chewing and swallowing food can release aromas that travel through the back of the mouth and up into the nasal passage.

The sense of touch (feeling of food)

The feeling of food in the mouth, or on the tongue, is important in the enjoyment of eating. During cancer treatment, food can feel ‘rough’ or ‘claggy’ and is sometimes described as ‘tasting like cardboard’.

Because they are so closely linked with taste, problems with the sense of smell or touch can be mistaken as a taste problem. This can be confusing and make the actual problem difficult to identify and treat. For example, a dry mouth or an offensive odour experienced in the mouth could be incorrectly described as a problem with the tastebuds.

Why are the senses affected?

The physical senses of taste, smell and touch are experienced when signals are sent from sensory cells in the mouth or nose to the brain. Many types of cancer treatment can interfere with the function of these sensory cells. Some treatments can also damage the nerves responsible for sending signals to the brain.

Surgery, chemotherapy and radiotherapy can all interfere with normal saliva flow. Saliva helps tastebuds to detect taste. Having a dry mouth over a long period of time can also result in mouth infections or tooth decay, which can cause further problems with taste, smell or feeling. 

Chemotherapy

Although the purpose of chemotherapy is to kill or injure cancer cells, it may also damage some healthy cells, including tastebuds. After chemotherapy, tastebuds begin to grow back quickly. This can confuse the taste processing centre in the brain and cause a change in the taste experience. Some types of chemotherapy can also affect nerve endings, which can change sensitivity to heat and cold.

Radiotherapy

Radiation to the head or neck area can cause direct damage to the surface of the tongue, mouth, nose or throat, resulting in changes to taste, smell or feeling.

Surgery

Some operations involve the physical removal of structures needed to experience taste or smell. For example, part of the tongue (including tastebuds), salivary glands, or parts of the nose or nasal passage may be removed or affected by surgery. 

The importance of a healthy diet

Eating well is important for anyone who has been diagnosed with cancer. Good nutrition helps the body cope with treatment and the healing process, and boosts energy levels and the immune system.

Changes in your enjoyment of food may lead you to choose less healthy food and drink options. You might find it difficult to follow your regular diet or the eating plan suggested by your treatment team.

If this occurs, let your treatment team know and ask for a referral to a dietitian, who can discuss strategies to make your eating plan easier to follow.

What changes could I experience?

The following problems are commonly experienced during cancer treatment.

The sense of taste

You might have problems identifying certain tastes during treatment, and for some people this may extend for some time after treatment. You might describe food as “not tasting like it used to”. For example, if you have trouble tasting salty, savoury or sour foods then sweet and bitter tastes might be overpowering. It is common for many people to find bitter foods (e.g. tea, coffee, beer, wine) or sweet foods (e.g. chocolate, sweetened breakfast cereals) unappealing during treatment. Many people start to prefer savoury foods over sweet foods, even if they usually have a sweet tooth.

The sense of smell

You may find it difficult to smell things at all, and this, in turn, will make it harder to taste. Or you might become very sensitive to smells that now seem stronger or different, or may make you feel nauseated. Some people may smell things when there is no odour present.

The sense of touch

If your sense of touch becomes highly sensitive, chilli or peppermints might feel too hot; fizzy drinks, including sparkling mineral water, might feel too abrasive; or you might not be able to tolerate the feeling or taste of very cold things, like cold drinks or ice-cream. If your sensitivity is reduced, you might find yourself adding lots of chilli or spice to food.

Changes in appetite or food preferences

Your motivation to eat or drink might change during cancer treatment. You may not be able to tolerate food you previously liked, or you might start to like foods you previously didn’t enjoy. Because cancer treatment can be stressful or associated with unpleasant feelings, such as nausea, certain foods or drinks can become associated with negative feelings. For example, if you associate the smell of pumpkin soup at the hospital with feelings of nausea, you might find it difficult to enjoy pumpkin soup again.

You may lose interest in food in general and find it hard to eat as much as you should. On the other hand, you might find you are craving particular types of food or are hungrier than usual.

Eating well is important for anyone who has been diagnosed with cancer. Good nutrition helps the body cope with treatment and the healing process, and boosts energy levels and the immune system.

Changes in your enjoyment of food may lead you to choose less healthy food and drink options. You might find it difficult to follow your regular diet or the eating plan suggested by your treatment team.
If this occurs, let your treatment team know and ask for a referral to a dietitian, who can discuss strategies to make your eating plan easier to follow.

How long do changes last?

Changes are rarely permanent, so most will resolve with time.

You might notice that symptoms change within the course of a single chemotherapy cycle. For example, flavour problems are usually worse in the first week after chemotherapy and then gradually improve until the next chemotherapy cycle.

Studies have shown that when people receive chemotherapy as the only type of cancer treatment, taste and food enjoyment usually returns to normal two months after treatment has finished. People who receive radiotherapy to the head or neck area can experience longer lasting problems, particularly because of ongoing problems with saliva flow.

What is the solution?

There are many strategies available to help relieve unwanted changes to the senses of taste, smell and touch. A dietitian can work with you to identify the causes and to develop a plan for managing the changes.

Diary

Keep a diary noting the symptoms you are experiencing and when they occur, particularly the time of day, the stage of treatment cycle, and with what food and drink. This will assist your treatment team to identify the causes and to find ways for you to manage the changes. 

Experiment

Experiment with foods and drinks. You may no longer enjoy your favourite foods, but find that you can tolerate or enjoy foods you previously didn’t. For instance, a preference for sweet or savoury foods often reverses during treatment.

Look for alternatives

If your food preferences impact on the quality of your diet, look for alternatives. For example, it is common to no longer enjoy meat during treatment.

However, meat is a good source of protein, which is an important nutrient to enable your body to cope with the demands of cancer and treatment. If you find meat less appealing, try other good protein sources such as cheese, eggs, nuts, dairy foods, baked beans, kidney beans, lentils or chickpeas.

More information

Call Cancer Council 13 11 20 for more information about changes to taste and smell. Trained health professionals can listen to your concerns, provide additional information, and put you in touch with local services.


Reviewed by: Dr Anna Boltong, Head of Cancer Information and Support Services, Cancer Council Victoria, VIC; Rosemarie Bartholomeusz, Registered Nurse, Chemotherapy Day Unit, Peter MacCallum Cancer Centre, VIC; Katherine Lane, Nurse Manager, Cancer Council Victoria, VIC; Wolfgang Marx, Dietitian and Nutritionist, and Senior Research Officer, University of Queensland, QLD; Gary Power, Consumer, QLD: Steve Pratt, Nutrition and Physical Activity Manager, Cancer Council WA, WA; Claire Smith, Chief Radiation Therapist, Oceania Oncology, QLD.

Updated: 12 Jul, 2015