Can potassium-rich foods lower your blood pressure and keep your heart healthy? (2024)

Can eating avocados, bananas and salmon lower your blood pressure and reduce your risk of heart attacks and strokes? And does this really only apply to women? We look behind the headlines and give our verdict.

Published 19 August 2022

Updated 25 August 2022

Research has suggested that eating more potassium-rich foods, such as avocados, bananas and salmon, can help counter the damaging effects of too much salt.

People who had the most potassium in their diet were 13 per cent less likely to have a heart attack or stroke than people who consumed the least, according to research published in the European Heart Journal.

The study also found that potassium-rich diets were linked with having lower blood pressure in women who eat a lot of salt.

Previous research has already shown that eating more salt is linked with having higher blood pressure and a high risk of heart attacks and strokes, while eating more potassium-rich foods has been linked with having lower blood pressure and a lower risk of heart attacks and strokes.

This research was trying to find out whether there is a difference in the way potassium affects men and women’s heart health. They also wanted to see if the benefits of a potassium-rich diet differed depending on how much salt you eat. Potassium increases the amount of salt that your body removes from the bloodstream (via your wee), so in theory more potassium might benefit people whose health would otherwise be at risk because they eat more salt. Past studies have suggested that women’s blood pressure is more sensitive to differences in salt intake, so the researchers were testing the theory that women might have more to gain from increasing the amount of potassium in their diet.

What did this research discover?

The researchers found that women in the group with the highest amount of potassium had an 11 per cent lower risk of having a heart attack or stroke, compared to those with the lowest amount of potassium. For men with the highest amount of potassium, the risk was 7 per cent lower.

The amount of salt in their diet didn’t appear to influence the relationship between potassium levels and the risk of having a heart attack or stroke. The researchers said that this suggests that the benefits of potassium aren’t just that it helps our bodies to get rid of salt: it must have some other protective effect too.

The study also found that the higher the amount of potassium people consumed per day, the lower their blood pressure. However, when they looked into the effect of gender, age and salt intake on this relationship, they found higher potassium levels were only linked with lower blood pressure in women eating the highest levels of salt, not in men.

One of the authors of the study said: “Our findings indicate that a heart healthy diet goes beyond limiting salt to boosting potassium content.

“Food companies can help by swapping standard sodium-based salt for a potassium salt alternative in processed foods.

“On top of that, we should all prioritise fresh, unprocessed foods since they are both rich in potassium and low in salt.”

The BHF verdict

Tracy Parker, Senior Dietitian at the British Heart Foundation (BHF), said: “This research supports current advice that cutting down our intake of salt and eating more foods containing potassium can be the recipe for a healthier heart.

An easy way to boost your potassium intake is by eating five portions of fruit and vegetables a day. Other foods like pulses, fish, nuts, seeds and milk are also high in potassium and low in salt, so can help benefit your heart.”

While foods that are good sources of potassium are easy to incorporate into a healthy, balanced diet, and will also have other benefits, don’t be tempted to try to increase your potassium intake with supplements unless these have been prescribed by your doctor.

Potassium is in such a wide variety of foods you should be able to get enough in your diet and taking supplements could result in too much potassium in your blood. This is especially important for older people and those with diabetes or kidney problems. Too much potassium can lead to stomach pain and diarrhoea, and high levels in the blood can lead to serious effects on the heart and its rhythm.

Certain medications, including ACE inhibitors and angiotensin receptor blockers (ARBs), and some diuretics (like eplerenone and spironolactone), may lead to raised levels of potassium, so talk to your doctor or pharmacist for advice - don't follow a potassium-restricted diet without checking with your doctor first.

How was this research carried out?

The study included 11,267 men and 13,696 women from the EPIC-Norfolk study, which recruited people aged 40 to 79 from general practices in Norfolk between 1993 and 1997.

The researchers took participants’ blood pressure and used urine samples to estimate the amount of salt and potassium in their diets. They divided them into three groups, according to their estimated potassium intake. The women with the highest levels of potassium were eating around 3.3g of potassium a day (3.5g for men), while those with the lowest intake of potassium were eating around 1.9g (2.2g for men). The reference intake (the guideline daily amount) for adults in the UK is 3.5g (3500mg) per day.

Researchers also looked at their medical history and asked them to fill in a questionnaire on their lifestyle, including questions about whether they smoked and how much alcohol they drank.

The men and women were then followed for an average of just under 20 years to see whether they had a heart attack or stroke.

How good was the research?

Strengths of this study are that it included a large number of people and had a long follow-up period, which mean they were able to base their statistics on a large number of heart attacks or strokes (13,596 people – over half the participants – had a stroke or heart attack in the 20-year follow-up period).

They were also able to adjust the results for factors which might have affected the results, such as age, body mass index (BMI), whether they were smokers, how much alcohol they drank, and their medical history of past strokes and heart attacks.

However, the study only included people from one county of England, so they may not reflect the whole population.

Determining how much potassium is in someone’s diet is not easy. The fact that the researchers used a urine sample means that their figures may be more accurate than people self-reporting what they ate. However, the urine sample was only taken once, so may not be representative of the person’s diet overall.

How good was the media coverage?

This study was widely reported, including in The Guardian and The Daily Mail.

The Guardian coverage was fairly accurate and included quotes from the researchers and a BHF dietitian, as well as helpful information about how much potassium people need and which foods contain it.

The Daily Mail was mostly accurate, except for when it said that “only women appeared to reap [the] benefit,” after saying “eating potassium may stave off a heart attack and stroke.” In fact, the study found eating more potassium was linked with a lower risk of having a heart attack and stroke in men, although not quite as much as in women.

The Mail article also focussed on avocado on toast, starting with the headline, “Confirmed: Avocado on toast is good for you! Scientists say potassium-rich foods keep heart healthy (but only for women!)”. While the study did find a stronger benefit for women, eating more potassium was linked to a reduction in heart attacks and strokes too.

However, the Mail did helpfully include information from the NHS Eatwell guide.

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