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Factsheet: Potassium

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What is it?

  • Potassium is important for the normal function of all nerves and muscles, including the heart.
  • Potassium levels in the body are controlled in health by the kidneys.
  • Potassium is present in many types of foods including fruit, vegetables, meat and milk.
  • Normal blood potassium level is 3.5-5.0 mmol/litre. (Your hospital may use a slightly different normal range, so check this locally)

What Happens in CKD

  • Potassium levels can increase (hyperkalaemia).
  • Certain medications such as ACE inhibitors (blood pressure tablets) and other factors such as constipation and blood transfusions can contribute to high potassium levels.
  • High blood potassium levels can interfere with normal muscle and nerve function and cause the heart to beat irregularly.
  • Low potassium levels (hypokalaemia) can develop in some people with certain tablets or poor food intake.

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Do you need a Low-Potassium Diet?

  • If your potassium levels are normal, you should not need a low potassium diet.
  • If your blood potassium level is too high, choosing low potassium foods, drinks and cooking methods instead of some of the high potassium alternatives can help to reduce it.
  • It’s also important to make sure that your diet stays balanced, nutritious and tasty.
  • Dietitians are trained to advise you on this.
Did you know? The chemical symbol for potassium is ‘K’ from its latin name Kalium.

Choosing a Low-Potassium Diet

Do NOT restrict your potassium intake unless you are advised to do so. Many high-potassium foods, such as fruit and vegetables, are an important part of a healthy diet.

If you have been advised by your doctor to eat less potassium, you should ask to see your local dietitian for advice on your own particular diet and medical condition. In the meantime there are a few general changes that can help.

  1. Do not use potassium-rich salt substitutes such as LoSalt, Ruthmol, etc. Instead cut down on salt by using more herbs, spices and other flavourings.
  2. Choose lower potassium drinks such as water, tea (black or herbal), squash, spirits, dry white wine, instead of higher potassium alternatives such as fruit juice, vegetable juice, smoothies, coffee, chocolate drinks, fortified wines and cider.
  3. Choose lower potassium snacks such as plain biscuits, cakes, crumpets, crackers, boiled sweets and mints instead of higher potassium choices such as chocolate, toffee, crisps, nuts, Bombay mix.
  4. Potassium dissolves in water. Where possible, boil your vegetables and potatoes before eating, baking, roasting or adding to stews, curries, soups or otherwise cooking further (throw away the cooking water)
  5. Fruit and vegetables – Don’t overeat. Keep to a maximum of five each day. A portion is about 80g or a ‘handful’. Fresh, frozen and tinned (without salt) are fine, but limit dried fruit and vegetables as they can be very high in potassium.

You will find kidney-friendly recipes and lots more information and practical advice on Potassium and other aspects of kidney diets in:-

Eating Well with Kidney Failure – A Practical Guide and Cookbook – by Helena Jackson, Annie Cassidy and Gavin James — published by Class Publishing. See Books page on this website.

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.

NKF Controlled Document No. 291: Factsheet: Potassium written: 24/10/2008 last reviewed: 20/10/2017