What is potassium?
Potassium is a mineral that your body needs every day. It helps your heart beat, your muscles move and your nerves send messages. We cannot function without this essential mineral.
Why can potassium be a problem in kidney disease?
When your kidneys are not working well, potassium can build up in the blood. This is called hyperkalaemia.
- High potassium is not harmful to the kidneys themselves. However, very high potassium levels can affect the way the heart beats and, in serious cases, can be dangerous.
- Low potassium can also be a problem and affect the heart.
The aim is balance: not too high and not too low.
Which foods contain potassium?
Potassium is found in most foods, but the amount varies.
Some foods contain more potassium than others, but potassium is naturally present in many everyday foods including fruit, vegetables, dairy foods, beans, nuts, meat and grains.
What affects the levels of potassium in the body?
The amount of potassium in your blood is influenced by much more than just the food you eat. Other factors include:
- High blood sugar (glucose) levels, commonly seen in diabetes
- Constipation
- Too much acid in the blood (metabolic acidosis), which is common in kidney disease
- A recent illness or infection
- Certain medications, including some medicines used to protect the kidneys and heart
- Very intense exercise, such as a recent high intensity workout
This is why two people eating the same foods may have very different potassium levels.
Should potassium-rich fruit, vegetables and wholegrains be avoided?
Potassium is found in lots of foods and a completely potassium-free diet doesn’t exist.
In the past, kidney patients were advised to avoid all high potassium fruit and vegetables, but many foods that contain potassium also contain other important nutrients like fibre, vitamins and protein.
The fibre content of high potassium wholegrains, fruit and vegetables is particularly important.
- Fibre may help reduce how much potassium your body absorbs from food. This makes it easier for your body to keep levels balanced.
- Fibre is also important for your gut, your heart, managing diabetes (if you have it), and your overall health.
Wholegrains, fruit and vegetables are not just high in potassium, they also offer health benefits.
What are potassium additives?
Potassium is found naturally in food, but it is also added to processed foods to make them taste better.
Potassium additives are absorbed very easily by the body, which means they will increase the level of potassium in your blood. Foods low in fibre can make this worse, as there is nothing to help limit how much potassium your body absorbs. This means potassium levels can rise more quickly. That’s why it’s better to eat fresh food whenever you can, and check labels for hidden potassium.
| E number | Potassium additive |
|---|---|
E508 |
Potassium chloride |
E332 |
Potassium citrate |
E340 |
Potassium phosphates |
How can I manage high potassium levels?
If your potassium level is high, there are simple steps that can help.
Speak to your healthcare team or dietitian before making changes; everyone is different. The advice you receive should be right for you.
- Some medications can raise potassium levels. However, many of these medicines are also very important for protecting your kidneys, heart or overall health. This means they are often continued, and dietary changes or other treatments may be used to help keep potassium levels safe.
- Choose more wholegrain, fibre-rich foods where possible.
- Follow portion advice if given.
- Avoid becoming constipated, as constipation can increase potassium levels. Staying active and including fibre-rich foods may help.
- Cook from scratch, using fresh ingredients, as much as possible.
- Limit highly processed foods, especially those with potassium additives. Check labels for ingredients with “potassium” in the name.
- In some situations, you may be prescribed medicines called potassium binders. These help remove extra potassium from the body through the gut.
- If your potassium is low, you may be advised to include more potassium-rich foods.
The aim is not to avoid potassium completely, but to find the right balance for your body.
Eating fruit and vegetables is important for staying healthy. Aim for at least five portions every day.
If you've been advised to eat less potassium, some fruits and vegetables have more potassium than others. These include plantains, bananas, mangoes, coconut and okra. It’s a good idea to only eat these now and then, and in smaller amounts.
Variety is key, so try different fruits and vegetables to keep meals exciting and healthy.
Tinned/canned beans or lentils will typically have a lower potassium content, but always remember to discard the water.
To reduce potassium, soak dried beans or lentils overnight in warm water then drain and discard the soaking water before cooking.
You can also pre-boil beans and lentils before using these in your cooking. Drain off and discard any water (avoid using the cooking water to make up sauces) to further reduce the potassium content.
Many people are surprised by how often potassium additives appear in everyday meals and snacks. Added potassium is often found in:
- Fruit juice, sugary drinks or diet soft drinks
- Crisps and low-fibre snack foods
- Chips or other processed potato products such as potato waffles
- Chocolate, cereal bars, cakes and biscuits
- Processed meats like sausages, bacon and ham, or breaded chicken or fish
- Ready meals and instant foods like pot noodles and soups
- Sauces, condiments and stock cubes – potassium is often added to the reduced salt versions of these foods.
Smoothies and fruit juices, whether fresh or from concentrates, can be high in potassium and low in fibre. If you drink these, keep your servings to no more than 150ml per day, or follow the advice your kidney dietitian has given you.
Try swapping potato or plantain crisps for corn-based options like popcorn. However, be mindful that some corn-based snacks may contain added potassium (read the label to check).
Low potassium recipes from Kidney Kitchen
If you have been advised to lower the potassium in your diet by your healthcare team, Kidney Kitchen recipes from Kidney Care UK can help you choose tasty meals.
- Each recipe has been expertly analysed: we have calculated how much potassium each recipe contains, so you don't need to.
- Despite sometimes containing a high-potassium ingredient, Kidney Kitchen meals are low in potassium because the overall amount of potassium in the whole meal is calculated, rather than a single ingredient on its own.
- Kidney Kitchen recipes are designed to help you enjoy balanced, home-cooked meals.
