Potassium is a mineral and electrolyte. It is essential for all of your body’s functions. It helps nerves and muscles function properly, as well as moving nutrients and waste around cells.
Role of potassium
Potassium is essential for life. It allows your nerves to respond to stimulation and muscles to contract (tighten), including those in your heart. It also offsets the effect of sodium (present in table salt) in raising your blood pressure, and moves nutrients into cells and waste products out of cells.
Most people get all the potassium they need from their food and drink, but having low or high potassium levels can potentially cause serious problems.
Risk of low potassium levels
If you have abnormally low levels of potassium in your body (known as hypokalaemia), you can feel weak and tired, get muscle cramps and become constipated.
You are at risk of developing low potassium levels if you:
- take diuretic (water) pills
- have vomiting or diarrhoea
- have a very physically demanding job
- live in extremely hot climates
- are a professional athlete
- don’t get enough potassium from your diet (though this is very rare)
Risk of high potassium levels
A high potassium level (hyperkalaemia) is a serious and potentially life-threatening condition. It is usually discovered through blood tests ordered to explain or monitor another condition.
If you have unusually high levels of potassium, you can feel weak and tired, feel nauseous and have an abnormal heart rhythm.
If you have these symptoms and believe your potassium levels might be high, contact your doctor immediately.
Most people get enough potassium from what they eat. There is plenty of potassium in:
- leafy greens, such as spinach, kale and silverbeet
- vine fruits, such as tomatoes, cucumbers, zucchini, eggplant and pumpkin
- root vegetables, such as carrots, potatoes and sweet potatoes
- tree fruits, such as avocados, apples, oranges and bananas
- beans and peas
- milk, yoghurt and meat
People who take certain types of diuretic may not get enough potassium from their diet. If you take diuretics, discuss this with your doctor.
Potassium supplements are usually needed only by people who take certain types of diuretics.
If you think you may need potassium supplements, talk to your doctor and have your potassium levels checked.
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Last reviewed: April 2019