Warning signs of low potassium, the mineral vital for heart health

Millions of Britons are deficient in a vital mineral that can slash the risk of heart attacks and stroke – but are completely unaware, according to experts.

As well as the long term effects, doctors say that low levels of potassium could explain a range of ‘mystery’ symptoms from a depressed mood, to dizziness and constipation.

‘Potassium deficiency is really common,’ says Professor John Young, a researcher at Teesside University.

‘This is largely due to poor diets, which are high in ultra-processed foods and salt, but also a lack of awareness. Unless levels are severely low and there is an underlying health problem with the heart or kidney, it is unlikely that someone will be diagnosed.’

Potassium plays a crucial role in nerve signalling, muscle contraction and maintaining a regular heartbeat.

It also helps regulate blood pressure by counteracting the effects of sodium, encouraging the body to excrete excess salt – a mechanism linked to lower risk of heart attack and stroke.

‘When someone has a small deficiency in potassium, their symptoms will include cramp, often in toes, constipation, they may come across as uptight, while some people also report headaches,’ says Professor Young.

‘While for someone with a severe deficiency – which is actually quite common – people may experience delirium-like symptoms, a depressive mood, and there may be an effect on the heart, like fluttering. There will also likely be gastrointestinal symptoms and potentially breathing problems.’

To avoid these symptoms the NHS and World Health Organisation (WHO) recommend adults consume 3,500 milligrams (mg) of potassium a day.

However data from the National Diet and Nutrition Survey — a large, ongoing survey of UK eating habits – shows that around 10 per cent of men and 24 per cent of women weren’t meeting the recommended intake of potassium.

The data also showed that a third of teenagers are also deficient in the mineral.

A 2024 research paper found that a dietary increase in blood potassium levels was associated with a ‘significantly lower risk’ – 24 per cent – of heart conditions, heart-linked hospitalisation or death from any cause, the results showed.

And a 2016 review of studies found that diets rich in potassium slashed the risk of having a stroke by 20 per cent.

To meet the necessary potassium intake, experts say that there are simple diet swaps that can make a difference.

‘Cutting down on salt is really important for maintaining potassium levels,’ says Professor Young.

‘This is because a combination of high sodium and low potassium makes symptoms worse. An easy swap is to use potassium chloride, known as low salt, on the table rather than normal sodium chloride.’

Experts say that there are also a number of foods that people should look to add to their diet to increase potassium levels, and it’s not bananas.

To meet the daily recommended intake someone would need to eat around 10 medium bananas.

‘Instead, foods like a baked potato with the skin on with beans would be a good source of potassium, as well as leafy greens,’ says Professor Young.

A banana contains around 500mg of potassium, half a baked potato contains around 600mg and a cup of raw spinach around 450mg.

Other key foods are spinach, lima beans, baked potato, yoghurt, banana, fruit juices and tuna. 

However Professor Young says that it is hard to get the necessary levels of potassium from food alone, so people should look to take supplements.

‘A multivitamin should be enough to supplement, but make sure to check the label to make sure it has potassium,’ he says.

It is a safe supplement to take as the majority of people can not ‘overdose’ on the mineral – despite what Peter Andre claimed when he was rushed to hospital after eating too many bananas.

The body can usually get rid of any excess potassium from food and drink. This is the job of the kidneys, which filter it out through urine.

For people with kidney disease, it’s harder for the body to do this, so a build-up is possible. This can be dangerous, causing irregular heart rhythms and even heart failure.

In people with advanced kidney disease, a low potassium diet is often needed to help maintain safe potassium levels.

Extreme potassium deficiency – known as hypokalaemia – in healthy people with normal kidney function is rare and unlikely to be a result of low dietary intake.

Instead, it’s usually caused by things like severe sickness and diarrhoea, the use of diuretics (which increase urine production) or laxatives. Eating disorders and alcohol misuse are also risk factors.

For most people potassium deficiency can be managed by diet, there are key signs the people need to watch for that may mean they need to see a doctor.

‘If you are experiencing chest pain, or dizziness from light exercise such as climbing a flight of stairs, then you should see a GP,’ says Professor Young.

‘But for most people the symptoms should act as a warning that their diet is not quite right.’

Last August, Danish researchers found that a diet rich in bananas, avocados and spinach can slash the risk of heart failure and death by almost a quarter.

Doctors found boosting patients’ intake of potassium through dietary changes, supplements or drugs significantly improved their heart health.