Millions of Britons are unknowingly suffering from a deficiency in potassium, a vital mineral that plays a crucial role in reducing the risk of heart attacks and strokes. Experts highlight that low potassium levels can manifest as a range of 'mystery' symptoms, from a depressed mood, dizziness, and constipation to more severe issues. Professor John Young of Teeside University emphasizes the commonality of potassium deficiency, attributing it largely to poor diets rich in ultra-processed foods and salt, alongside a general lack of public awareness. Diagnosis is rare unless levels are severely low or an underlying heart or kidney problem exists.

Potassium is essential for several bodily functions, including nerve signalling, muscle contraction, and maintaining a regular heartbeat. Furthermore, it helps regulate blood pressure by counteracting the effects of sodium, facilitating the excretion of excess salt from the body. This mechanism is directly linked to a lower risk of heart attack and stroke. Professor Young details the symptoms associated with varying degrees of deficiency: mild deficiencies can cause cramps, often in the toes, constipation, and headaches, and may contribute to an 'uptight' demeanor. Severe deficiencies, which are surprisingly common, can lead to delirium-like symptoms, a depressive mood, heart palpitations, gastrointestinal issues, and even breathing problems.

To prevent these health issues, the NHS and World Health Organisation (WHO) recommend that adults consume 3,500 milligrams (mg) of potassium daily. However, data from the National Diet and Nutrition Survey, a comprehensive study of UK eating habits, reveals that a significant portion of the population falls short of this recommendation. Approximately 10 percent of men, 24 percent of women, and a third of teenagers in the UK are not meeting their daily potassium intake. The benefits of adequate potassium are well-documented: a 2024 research paper found that an increase in dietary blood potassium levels was associated with a "significantly lower risk" – 24 percent – of heart conditions, heart-linked hospitalisation, or death from any cause. Similarly, a 2016 review of studies demonstrated that diets rich in potassium could slash the risk of having a stroke by 20 percent.

Achieving the necessary potassium intake often involves simple dietary adjustments. Professor Young advises that reducing salt intake is paramount for maintaining healthy potassium levels, as a combination of high sodium and low potassium exacerbates symptoms. He suggests using potassium chloride, often marketed as 'low salt,' as an easy alternative to normal sodium chloride. While a banana contains around 500mg of potassium, reaching the daily recommended intake would require consuming approximately ten medium bananas, making it an impractical sole source. Instead, experts recommend incorporating foods like a baked potato with the skin on served with beans (half a baked potato contains about 600mg), leafy greens such as spinach (a cup of raw spinach has around 450mg), as well as yoghurt, fruit juices, and tuna.

Despite the availability of potassium-rich foods, Professor Young notes that it can be challenging to obtain sufficient levels from diet alone, suggesting that supplements may be beneficial. A multivitamin typically provides adequate supplementation, but checking the label for potassium content is recommended. Potassium supplements are generally safe for most individuals, as the body, primarily through the kidneys, efficiently filters out and excretes any excess potassium through urine. This process prevents an 'overdose' on the mineral, despite anecdotes such as Peter Andre's hospitalisation after consuming numerous bananas, which was likely unrelated to potassium toxicity in a healthy individual.

However, specific health conditions can affect potassium regulation. For individuals with kidney disease, the body struggles to excrete excess potassium, leading to a potentially dangerous build-up that can cause irregular heart rhythms and even heart failure. In such cases, a low potassium diet is often prescribed to maintain safe levels. Extreme potassium deficiency, known as hypokalaemia, is rare in healthy people with normal kidney function and is usually not a result of low dietary intake. Instead, it is typically caused by severe sickness and diarrhoea, the use of diuretics or laxatives, eating disorders, or alcohol misuse.

For the majority, potassium deficiency can be managed effectively through diet. Nevertheless, certain symptoms warrant medical attention. Professor Young advises consulting a GP if experiencing chest pain or dizziness from light exercise, such as climbing a flight of stairs. For most, these symptoms serve as a crucial warning that their diet requires adjustment. Further reinforcing the importance of this mineral, Danish researchers found last August that a diet rich in bananas, avocados, and spinach could slash the risk of heart failure and death by almost a quarter, demonstrating how boosting patients’ potassium intake through diet, supplements, or medication significantly improved their heart health.