A banana a day could prevent a deficiency which, scientists say, might increase the risk of stroke.
The tropical fruit is rich in potassium, and a study of 5,600 people aged over 65 suggested that those with the lowest intake of the mineral were 50% more likely to suffer a stroke.
The study also suggested that people who take diuretic drugs - which increase the amount of water excreted in the urine - may also increase the risk, perhaps because they stop potassium from the diet being absorbed by the body.
Diuretics are frequently prescribed to older people - ironically, to control blood pressure and reduce the chance of one type of stroke.
Patients with heart failure also take the drugs to relieve the strain on their heart and lungs.
Patients taking diuretics with the lowest levels of potassium in their blood were two-and-a-half times more likely to have a stroke compared with diuretic takers who had the highest levels of potassium.
Source BBC News