Going bananas for potassium?


“A banana a day can help keep strokes at bay”

Daily Express 4 September 2014

The BHF’s view

Women who get higher levels of potassium from their diet are less likely to have a stroke or die, according to research reported in the Express, Mail and Telegraph and online.

The study of 90,000 postmenopausal US women found that most were not getting the recommended intake of potassium. It is found in fruits and vegetables, pulses, nuts, seeds, fish and shellfish, so it shouldn’t be necessary to take supplements.

Previous studies show that our potassium intake has fallen in recent decades, probably because we’re eating more processed foods and fewer fruits and veg.

Getting the recommended amount of potassium has previously been shown to help lower blood pressure in people who have high blood pressure (hypertension). But in this study, the biggest benefit from potassium was found among people who did not have high blood pressure.

The study authors suggest that the health benefits they found may be because higher potassium intakes can prevent arterial stiffness.

After adjusting for other factors, the group who got most potassium from their food had about a 27 per cent reduction in ischaemic stroke risk compared with those who ate least, and were about 10 per cent less likely to die.

A strength of this study is that it was based on a large number of people, but a weakness is that people may not have accurately reported what they had eaten.

The study did not look at salt intake – which is linked to high blood pressure and stroke – so it’s not clear what effect that might have had on the results. It’s also not clear whether the results would have been the same in men or younger women.

An easy way to boost your potassium intake is making sure you are eating your five portions of fruit and veg a day

The media coverage was broadly accurate, but sometimes oversimplified. In particular, the Express headline suggests that a banana a day would be enough to meet your potassium requirements, whereas, in fact, a banana contains about 11 per cent of the 3,500mg recommended by UK dietary guidelines.

The Express article said: “It means people could protect themselves from suffering a disability and often deadly stroke simply by ensuring they eat plenty of bananas, white and sweet potatoes and white beans.” Although doing this may reduce your risk, the study did not prove that; it suggested an association, rather than proving cause and effect. And there are many other factors that affect stroke risk, including salt and alcohol consumption.

Tracy Parker, our Heart Health Dietitian, said: “An easy way to boost your potassium intake is making sure you are eating your five portions of fruit and veg a day.

“Keeping an eye on your alcohol intake and keeping physically active will also help to reduce your blood pressure and reduce your risk of stroke.”

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