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Potassium is a mineral that is important for the balance of fluids in the body and for the heart, kidneys and other organs to function normally.

Potassium is found in fruit, such as bananas, and most people get all the potassium they need from a healthy balanced diet that includes fruit, vegetables and protein.

Potassium is also available in supplements, but too much potassium can be harmful, especially for people with kidney disease or those taking some drugs to treat high blood pressure.

Potassium uses

Low potassium is associated with a risk of abnormal heart rhythms. For people with low potassium, doctors sometimes recommend an improved diet or potassium supplements.

Potassium deficiencies are more common in people who:

  • Take certain medicines, such as diuretics and certain oral contraceptives
  • Have physically demanding jobs
  • Are athletes
  • Have health conditions that affect their digestive absorption, such as Crohn’s disease
  • Have an eating disorder
  • Smoke
  • Abuse alcohol or drugs

Potassium doses and instructions for use

UK guidelines say adults need 3,500mg of potassium a day.

Taking too much potassium can result in stomach pain, nausea and diarrhoea.

The Department of Health says taking up to 3,700mg a day is unlikely to cause any harm.

Older people can be at a higher risk from too much potassium because as we age, the kidneys become less efficient at removing potassium from our blood.

Potassium food sources

Good natural food sources of potassium include:

  • Bananas and other fruit
  • Nuts and seeds
  • Vegetables and pulses
  • Milk
  • Fish and shellfish
  • Beef, chicken and turkey
  • Bread

Certain types of cooking, such as boiling, can destroy the potassium in some foods.

Potassium supplement information

Potassium supplements are sold as tablets, liquids and powders. At higher doses, potassium supplements require a prescription. As with any supplement, keep potassium supplements in a cool, dry place, away from humidity and direct sunlight.

Potassium warnings

  • Side-effects. At normal doses, potassium is fairly safe. It may cause an upset stomach, nausea or diarrhoea. Some people have allergies to potassium supplements.
  • Interactions. Potassium supplements may not be safe if you take medicines for diabetes or heart disease. Check with your doctor.
  • Warnings. People with kidney disease, diabetes, heart disease, Addison’s disease, stomach ulcers or other health problems should never take potassium supplements without first consulting a doctor.
  • Overdose. Signs of a potassium overdose include confusion, tingling sensation in the limbs, drop in blood pressure, irregular heartbeat, weakness and coma. Seek emergency medical help.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on July 29, 2015

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