Controlling potassium intake: advice for people living with kidney disease

This booklet has been developed by renal dietitians, to provide advice for people who have been told that they need to lower their potassium levels. Please use this leaflet alongside the advice given to you by your renal dietitian.

Only follow this advice if you have been told that you need to follow a low potassium diet.

What is potassium?

Potassium is a mineral needed by the body to ensure healthy nerve and muscle function, including the heart. Potassium is found naturally in many foods and drinks.

Why are my potassium levels too high?

• The amount of potassium in your blood is controlled mainly by your kidneys. If your kidneys do not work properly, they are unable to remove excess potassium from your body, and the potassium in your blood can increase to dangerous levels.

• Your body also removes potassium through your bowel, so potassium levels can become high if you are constipated.

• Certain medication may also raise potassium levels. Your kidney doctor can discuss this with you in more detail.

What happens if my potassium levels become too high?

Some people do not have any symptoms at all, but high levels of potassium in the blood can lead to muscle weakness. If levels become too high, this can disrupt the heart rhythm and cause the heart to stop. Your doctor will tell you if you have high levels which need to be lowered.

How will I know if my potassium levels are too high?

The only way to know is to have a blood test. The healthy range for potassium is 3.5 to 5.3 mmol/l.

How can I control my potassium level?

In order to control your potassium levels, you need to either:

• Follow a low potassium diet, with guidance from a registered dietitian.

• Make sure you have regular bowel movements; speak to a renal dietitian if you would like advice on this.

• Have regular dialysis (if needed).

How do I follow a low potassium diet?

Potassium is found in a large number of foods and drinks. You do not need to avoid all foods, but may need to limit some foods that are high in potassium. It is also important to stick to the recommended portion sizes. This booklet will explain which foods are high in potassium, and which foods you can eat instead (suitable alternatives).

It is important to remember that not everyone needs to limit how much potassium they eat or drink, and the advice you are given may change depending on your blood results. Your renal dietitian can give you more personalised advice.

Fruits and vegetables

Fruit and vegetables are a good source of fibre, vitamins, and minerals. They are important to include as part of a balanced diet. They are also important for healthy bowel function. If you are limiting potassium in your diet, stick to a maximum of 2 portions of fruit and 2 portions of vegetables each day. Try to include a variety, but limit how many of the higher potassium foods you eat (these are listed at the end of this leaflet).

A portion is approximately 80g (roughly the amount that fits in the palm of your hand). Examples include:

• Large fruit: ½ grapefruit or orange, 1 slice of pineapple, or 2 slices of mango.

• Medium fruit: 1 apple, 1 pear, 1 peach, or 1 nectarine.

• Small fruit: 2 plums, 2 satsumas, 1 handful of berries or grapes.

• Tinned fruit: ½ tin or 3 tablespoons.

• 2 to 3 heaped tablespoons of cooked vegetables.

Potatoes

• Limit potatoes to one serving each day. A serving is 2 to 3 egg-sized potatoes.

• Make sure the potatoes are boiled in plenty of water, and throw out the cooking water. Boiling may help to reduce the potassium content of the food by 60 to 80%.

• Avoid jacket potatoes, crisps, oven chips, and any other potato-based products which have not been boiled first. For example, instant mashed potatoes, croquettes, wedges, or hash browns.

Dairy products

Dairy products contain important nutrients for a healthy diet. However, they should be eaten in moderation if you are restricting potassium in your diet.

• Limit milk to no more than 190ml each day. This includes skimmed, semi skimmed, and full fat cow’s milk.

• Soya milk has a similar potassium content to cow’s milk; so this should also be limited to 190ml each day.

• Double cream can be diluted with water and used instead of milk. Mix one part cream with one part water; add more water if you like.

• Rice, oat, and hemp milk can be used in unlimited amounts, as an alternative to milk.

• Other dairy products can be used in place of the milk. For example two scoops of ice cream, a small pot of yoghurt (125g), or 2 to 3 tablespoons of custard.

• Avoid milk powder, tinned milk, or coconut milk as they are very high in potassium.

Cooking tips to lower potassium levels

• Cut vegetables and potatoes into small pieces before boiling. This will make sure that some potassium comes out of the food during cooking.

• Peel and parboil vegetables or potatoes before adding to stews, soups, or curries. This will help to remove some potassium from the foods.

• Boil vegetables and potatoes in plenty of water, and throw the water away afterwards. Do not use it to make soup, sauces, or gravies, as some potassium will come out of the vegetables into this liquid, making it very high in potassium.

• Avoid stir frying, microwaving, steaming, or pressure-cooking vegetables. This keeps the potassium in the food.

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Food labels and additives

• It is important to check food labels for hidden sources of potassium from additives.

• Potassium chloride is often used in processed foods as an alternative to salt.

• Potassium sorbate is also found in some foods and drinks.

• It is very difficult to know how much potassium is found in these foods and what effect they may have on your blood levels.

• Try to limit foods which contain potassium additives.

Speak to your dietitian for more information about this.

Salt substitutes such as Lo-Salt and So-Low are not recommended, as they contain high levels of potassium in place of sodium. Be careful when using products labelled as ‘low sodium’ or ‘reduced salt’ as they may contain salt alternatives. Always check the ingredients list.

Fruit

Vegetables

Meat, fish, and alternatives

Cereals

Bread

Starchy foods

Savoury snacks

Biscuits and cakes

Puddings

Confectionary

Drinks

Other foods

Further information

• Kent Kidney Patients Association

• Kidney Care UK

• Kidney Kitchen: Kidney Care UK
  Provides kidney friendly recipes and booklets to download.

• Kidney Research UK

• National Kidney Federation (NKF)

If you have any questions, please contact the renal dietitians on 01227 868789.

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