Ultimate guide to potassium: function, foods, deficiency and supplements

When we think about vitamins and minerals, potassium isn’t usually the first that comes to mind. But that makes it no less important – potassium plays essential roles in a number of processes in our bodies.^1-3 

The question is, are we getting enough from our diets alone, or do we need supplements to boost our intake?

By keeping your body in rhythm, potassium has several important roles in the body, including contributing to:^2,3 

Maintaining these everyday processes may affect your health outcomes in the future too. Potassium helps to control blood pressure by balancing the effects of sodium (which increases blood pressure) and relaxing tension in blood vessel walls.⁴ One study, published in the Journal of the American Heart Association, found that people who had more potassium in their diet were 13% less likely to have a heart attack or stroke than those who had the lowest amount.⁵

In addition, a potassium-rich diet may support bone health by lowering the amount of calcium lost via the kidneys.⁶

Check out the table below to see how much you and your family should be aiming for every day:

You can also find potassium in meat, such as beef, chicken, turkey and fish.⁷

Because potassium is used in lots of different ways in the body, a deficiency may lead to a range of symptoms. These can include:^2,9 

Hypokalaemia can be caused by prolonged diarrhoea, vomiting or taking diuretics.² People with kidney disease, inflammatory bowel disease or pica are also more at risk of having low potassium levels.^2,9

Most people don’t need to worry about having too much potassium in their diets, as the kidneys remove excess amounts via urine.¹⁰ And if you’re taking potassium supplements, then 3,700mg or less a day is pretty unlikely to have any harmful side effects. 

However, those with kidney problems, older people and people taking blood pressure medications may be at risk of harm from potassium if they have too much.^7,10

Having too much potassium in your blood is called hyperkalaemia.¹¹ Symptoms don’t always appear – if they do, they’re usually mild and include muscle weakness, tingling, nausea, stomach pain and diarrhoea.^7,11

However, in some rare cases, people may be more at risk of a potassium deficiency. This includes those with kidney disease or inflammatory bowel disease, or people taking laxatives or diuretics.^2,9 

You may be recommended a potassium supplement if you have high blood pressure¹² but you should only take it under your doctor’s guidance. If you’re on any other medication, tell your doctor before taking a potassium supplement, as it may interact with certain medicines, including angiotensin-converting-enzyme (ACE) inhibitors and loop diuretics.¹² 

Children don’t need to take potassium supplements. According to the World Health Organisation, children aged 2–15 years old should be able to get the potassium they need from a healthy and balanced diet.¹³ But, if you think your child might benefit from a few extra nutrients speak to a dietician or registered nutritionist and check out our recommended supplements for children.

Older people should only take potassium supplements if their doctor has advised them to. This is because, with age, our kidneys may have a harder time removing excess potassium from our blood.⁷