Taste changes (known as dysgeusia) including blandness, saltiness, bitterness, a metallic taste, or an aversion to meat, are common in people with chronic kidney disease (CKD).
“Around one in three people with kidney disease is affected by taste changes,” says Dr Graham Lipkin, a consultant nephrologist at Queen Elizabeth Hospital Birmingham and chair of trustees at Kidney Care UK.
“People often mention how their taste has changed during clinic consultations, particularly those on dialysis or later stage disease, and it gets progressively worse as CKD advances.
Taste changes can really affect quality of life and spoil your enjoyment of food and even lead to malnutrition and weight loss, as well as nausea, so it’s by no means a trivial problem. Kidney doctors probably don’t give it as much attention as other complications of CKD, but it causes a lot of distress.Dr Graham Lipkin, consultant nephrologist at Queen Elizabeth Hospital Birmingham
“If your food tastes horrible or you can’t taste at all, and you don’t feel that well, that will make it less likely that you will eat. It’s always worth mentioning these changes to your kidney team.”
What taste changes do people with CKD notice?
“I see a lot of people with advanced disease in clinic really struggling with taste changes,” says Joanna Pulman, lead kidney dietitian at Dorset County Hospital.
“They’ll say things like ‘it’s like eating cardboard’ or that food tastes of nothing, or they may complain of having a horrible, non-specific taste in their mouth.
“Others will have a metallic taste or will go off certain foods they’ve previously liked, such as meat. It really does spoil their enjoyment of food, and this can lead to loss of appetite and weight loss and can increase the risk of patients becoming malnourished.
“Many of these people will already be dealing with other complications of advanced CKD such as nausea and sickness, or they may have issues with their bowels, so they may not be particularly well nourished. On top of that they have got taste changes to deal with too.”
What causes taste changes in CKD?
The main reason cause of taste changes in CKD is likely to be a build-up of toxins such urea in the blood.
Urea is produced as the body digests certain foods, particularly high protein foods such as meat. In kidney failure, the kidneys are not able to remove these toxins as they usually would. This can affect how the taste buds function, and therefore how taste is perceived.
In addition to this, if people have been advised they need to limit their fluid intake, or take certain medications, they may find having a dry mouth can exacerbate issues with taste.
“The proposed causes are accumulation of poisons in the body, which would explain why taste changes are more common in advanced disease rather than in early disease,” explains Dr Lipkin.
“Other causes include side effects of drugs, particularly ACE inhibitors and calcium channel blockers (used to control blood pressure) and even statins (to lower cholesterol). Most people with CKD will be taking one or more of these medications.
“Fluid restriction in people with advanced CKD probably adds to the taste disturbance that people get.”
Joanna says another cause can be changes in the composition of saliva in CKD, which can lead to a bitter or metallic taste in the mouth.
“One theory for why people go off meat is that meat has a high protein content, which produces a lot of urea when it is broken down, and that going off meat is the body’s protective mechanism to prevent urea levels getting too high.”
The science of taste
Our tongues can detect five basic tastes: sweet, sour, salty, bitter and umami (savoury). There are between 2,000 and 4,000 tastebuds, mostly on the tongue but also on the back of the throat and inside the cheeks and the nasal cavity.
Taste is also influenced by the smell of foods, the temperature, and texture. These sensations are all processed in the nose, and signals sent to the brain.
How are taste changes in CKD treated?
“Treatments for taste changes are limited, and more research is definitely needed,” says Dr Lipkin. “There is some suggestion that zinc supplements may help, and you could speak to your doctor about changing the type of medication you are on if taste change is a side effect, but that can be difficult in some cases.”
Expert tips for improving your sense of taste if you have dysgeusia
Joanna advises maintaining a good oral hygiene routine as a starting point: cleaning teeth, flossing and tongue brushing to keep the mouth fresh, as well as visiting the dentist regularly to check for any underlying dental problems.
If taste changes are particularly problematic, Joanna suggests making up a solution of sodium bicarbonate to use as a mouth wash four times a day. Mix one level teaspoon of sodium bicarbonate in 500 ml of water. Use approximately 10-20 ml for each rinse, gargle and spit out. Make a fresh jug daily.
“If someone with CKD is on fluid restriction or taking certain medications, they may have a dry mouth. Treatment might focus on treating that first to see if it makes a difference,” says Joanna.
“The first thing people will be advised to do is to follow a ‘no added salt diet’. Avoid adding any salt (or salt substitutes) to food and try to avoid foods that are high in salt such as processed foods, fast foods, and takeaways and savoury snacks. Small changes such as having regular sips of water (within your fluid allowance if you have one) and regularly rinsing your mouth out with water, especially just before eating, will help freshen up the mouth, as can using sugar-free chewing gum to promote saliva production, or using artificial saliva products to help a dry mouth when they are not able to drink a lot.
“Other tips include stimulating more saliva by sucking sugar-free hard sweets or frozen fruit segments, allowing these to defrost slightly to prevent them sticking to the lips or mouth.”
“Try sipping a glass of ginger beer or fruit juice or a cup of peppermint tea before eating to stimulate different taste buds,” suggests Joanna. “Menthol sweets or chewing gum may have this effect too.”
Experiment with different flavours, including flavours that you have not previously enjoyed, as you may find that some of these tastes are more palatable now.
“If you have a bitter taste in your mouth, try avoiding bitter foods such as coffee, chocolate and beer,” advises Joanna. “If foods are tasting too salty, eating sweet foods may help.”
“You could also use sweet flavours to counter bitterness by glazing meat with honey or swapping to a malted milk or hot chocolate drink rather than a coffee.”
The same things will not work for everyone, so experiment and try different things to find what works for you.
“If you have a metallic taste in your mouth, you could try using stoneware and glassware for cooking rather than metal saucepans and trays and swapping metal cutlery for plastic utensils to see if this helps,” says Joanna.
“Adding spices such as chilli or herbs to dishes can make foods tastier, "says Joanna. “You could also add more acidic flavours by marinating meat in lemon or lime or using a vinegar-based salad dressing.”
“Look at stimulating all the senses involved in taste. For example, hot food may be more appealing than cold food, some textures may feel more pleasant in the mouth than others and the smells /aroma of some may also be more appetising,” says Joanna.
“Cold foods will leave less of a bitter taste, so try allowing food to cool down, or eat cold foods such as sandwiches to see if that makes a difference.”