What are taste and smell changes?
Around 80% of people undergoing cancer treatment report changes in the flavour of food. This has the potential to affect how they enjoy food and can lead to a less nutritious diet.
Flavour is experienced via three senses – taste, smell and touch (how food feels in your mouth) – and these can change as a result of cancer treatment.
We experience taste when food or drink, mixed with saliva, reaches tastebuds all over the tongue and inside the mouth. The tastebuds will detect the five basic tastes of sweet, sour, bitter, salty and savoury (also known as umami). These building blocks of flavour combine with sense and touch, giving rise to many flavours.
Smell is experienced when odour particles are detected in the air and then enter the nose through the mouth or nostrils. When we chew and swallow food, odours can be released that travel through the back of the mouth and into the nasal passage.
Why are my senses affected?
Taste, smell and touch are experienced when signals are sent from sensory cells in the mouth or nose to your brain and many types of cancer treatments can interfere with the function of those cells. In addition, some treatments can damage the nerves that send signals to the brain.
Chemotherapy
Chemotherapy aims to kill or slow the growth of cancer cell but may also damage healthy cells, including tastebuds. After chemotherapy, your tastebuds will grow back quickly which can confuse the taste process centre in the brain. In addition, some types of chemotherapy can affect nerve endings which can change your sensitivity to cold and heat.
Radiation therapy
If you have radiation therapy to the head or neck region, it can cause damage to the surface of the tongue, mouth, nose or throat which can result in changes to smell, taste or feeling of food.
Surgery
Some surgical procedures may involve the physical removal of structures such as parts of the tongue, salivary glands or parts of the nasal passage, which are needed to experience taste.
What changes will I experience?
You may find that food ‘doesn’t taste like it used to’ as you might have problems identifying certain tastes during treatment and even for some time after treatment. You may have trouble tasting salty, savoury or sour foods which can make sweet and bitter tastes overpowering. Many people find they do not like bitter and sweet foods during treatment.
You may also find it difficult to smell things which makes it difficult to taste. You may also become sensitive to certain food smells. Your sense of touch may also become very sensitive so things like mints or chilli may feel too hot, fizzy drinks may feel abrasive and you may find very cold things like ice-cream difficult to tolerate. Alternatively, your sensitivity may be reduced.
During treatment you may lose interest in food and find it harder to eat as much as you should. Or you may find that you are hungrier than usual. Talk to your doctor about managing the changes.
How long will changes to taste and smell last?
Most changes to your sense of taste and smell will resolve with time and are rarely permanent. Studies have shown that if you only have chemotherapy, your enjoyment of food usually returns about two months after treatment. If you have radiation therapy to the head or neck, you may experience longer lasting effects.
How can I manage the changes to taste and smell?
There are a number of ways you can help relieve unwanted changes to taste and smell. A dietitian can work with you to develop a plan for managing any changes. Some suggestions include:
- experimenting with foods and drinks if you are no longer enjoying your favourite foods
- look for alternatives, for example if you find meat unappetizing, look for alternative good protein sources such as cheese, nuts, eggs and lentils or chickpeas
- ensure any nausea caused by treatment is well controlled
- removing yourself from food preparation areas or asking friends and family to prepare food for you if the smell of food bothers you
- practicing good oral hygiene during and after treatment.
