Scientists say eating a high-potassium diet including foods such as bananas, spinach and baked potatoes could boost heart health and slash the risk of heart failure
Eating bananas could slash our risk of heart failure and death, research suggests.
The bendy fruit is high in potassium and a study has shown people with heart problems cut their risk by a quarter by consuming more of the essential mineral. A trial of 1,200 patients with implantable defibrillators showed boosting potassium cut their risk of hospital admissions for irregular heartbeat or heart failure and death by 24%. Other foods high in potassium are cabbage, spinach, broccoli, brussel sprouts and baked potatoes.
Study author Professor Henning Bundgaard, of Copenhagen University Hospital, said: “Higher dietary intake of potassium may not only benefit patients with heart diseases but probably all of us, so maybe we should all reduce sodium and increase potassium content in our food.”
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The study, presented at the European Society of Cardiology Congress in Madrid, looked at the impact of adding potassium to diets in the form of food and supplements.
Western diets are generally high in salt, also called sodium, which is hidden in a lot of processed foods. Consuming a lot of salt is linked to higher blood pressure and a greater risk of heart attacks and strokes.
Potassium is an electrolyte vital for nerve function, muscle contraction and keeping a regular heartbeat. It also increases the amount of salt that your body removes via your wee.
Prof Bundgaard said: “The human body evolved on a potassium-rich, sodium-poor diet when we were born and raised on the Savannah eating fruit and vegetables.
“We now tend to go to a modern diet that is processed foods and, the more processed, we see more and more sodium in the food and less potassium. The ratio between the two has changed from 10:1 to 1:2 which is a dramatic change. Potassium is crucial for cardiac function and we know from observational studies that low potassium increases the risk of arrhythmias and heart failures and death.
“If we go below the normal range there is a marked increase in cardiovascular events. Even within the normal range we have a higher risk at low-normal potassium compared to high-normal. The simple question we asked in the trial was would we benefit the patients by increasing potassium?”
A banana contains around 500mg of potassium, half a baked potato contains around 600mg and a cup of raw spinach around 450mg.
Prof Bundgaard put participants on a high potassium diet of plant-based foods but did not recommend meat, which is also potassium rich – “because it is also rich in sodium and counter-interacts the increase in potassium”.
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The National Institutes of Health recommends that adult males should consume 3,400mg of potassium daily and adult females should consume 2,600mg. Pregnant or breast feeding women should consume significantly less and should consult a specialist if concerned.
Professor Jose Luis Merino, a cardiology expert from La Paz University Hospital in Madrid, said it was best to get potassium from whole foods if possible rather than supplements.
He said: “You can get potassium from fruits, such as bananas and orange juice, but interestingly, other foods are higher in potassium, spinach, baked potatoes and also lentils.”
Typically concentrations of potassium in the blood range from about 3.6 to 5.0 millimoles per litre (mmol/L).
Half of the 1,200 trial participants had their potassium boosted using dietary changes, supplements and a type of drug called a mineralocorticoid receptor antagonist (MRA) which prevents the loss of potassium. Their levels increased from 4.01 mmol/L to 4.36 mmol/L after six months. The non-potassium boosted group had an average level of 4.05 mmol/L after six months.
Those ingesting more potassium had less treatments for irregular heart beat, and less planned hospitalisations due to irregular heart beats or heart failure. Some 6.7% of patients on a potassium-rich diet were hospitalised due to an irregular heartbeat, compared to 10.7% in the lower potassium group.
And 3.5% of patients on a potassium-rich diet experienced heart failure, compared with 5.5% in the non-potassium boosted group.
The study authors concluded: “Higher dietary intake of potassium may not only benefit patients but all of us. We should probably all reduce sodium and increase potassium content in our food.”
Dietitian Dr Carrie Ruxton said: “Everyone knows about cutting down on salt, but few people realise that increasing potassium is almost as important for preventing strokes and heart attacks.
“The latest National Diet and Nutrition Survey published this year shows that a third of teenagers and a quarter of adults are at risk of potassium deficiency, with implications for blood pressure control and muscle function.
“We can do more individually to boost our potassium intakes by eating more fruit, vegetables and fish. Fruit juices are particularly rich in potassium. Other key foods are spinach, lima beans, baked potato, yoghurt, banana and tuna.”
Milk, coffee and tea are also sources of potassium.
Consultant cardiologist Dr Sonya Babu-Narayan, director at the British Heart Foundation, said: “If you’re advised by your doctor to improve your dietary potassium intake, you can do this by including more vegetables and fruit rich in potassium such as spinach, bananas or avocados in your diet, as well as pulses, fish, nuts, and seeds.
“Don’t be tempted to try to increase your potassium intake with supplements unless supervised by your doctor, as ending up with too high a potassium level is dangerous – for example it can cause cardiac arrest.”
