Millions of lives could be saved every year if people ate more potassium-rich foods such as bananas and cut down on their salt intake, research suggests.
People who have a high potassium intake have a 24% reduced risk of stroke, according to a new study.
And increasing levels of potassium - which can be found in many foods including fruit, vegetables, nuts, seeds, milk, fish, beef, chicken, turkey and bread - can help to reduce high blood pressure, the results indicate.
Researchers also said that increased levels of the chemical do not have an adverse effect on kidney function in adults.
Previous studies have suggested that older people are at an increased risk of harm from potassium because as people get older, their kidneys may become less able to remove potassium from their blood.
The Department of Health advises that older people should not have potassium supplements unless advised to take them by a doctor. It says that adults need 3,500mg of potassium a day - which people should be able to get from eating a balanced diet.
The research, published on bmj.com, analysed data on potassium intake and health concerning 128,000 participants, who took part in 33 trials.
The authors wrote: "High quality evidence shows that increased potassium intake reduces blood pressure in people with hypertension and has no adverse effect on blood lipid concentrations, catecholamine concentrations, or renal function in adults.
"Higher potassium intake was associated with a 24% lower risk of stroke.
"These results suggest that increased potassium intake is potentially beneficial to most people without impaired renal handling of potassium for the prevention and control of elevated blood pressure and stroke."
In separate research, also published on the journal's website, the effects of modest salt reduction on blood pressure, hormones, and blood fats were examined.
The authors looked at data from 34 trials involving over 3,200 adults.
They found that a modest reduction in salt for four or more weeks led to significant falls in blood pressure in people with both raised and normal blood pressure - and could therefore reduce people's risk of strokes, heart attacks, and heart failure.
Similar results were found in another piece of research published on the website. The authors noted: "Reduced sodium intake reduces blood pressure and has no adverse effect on blood lipids, catecholamine levels, or renal function, and moderate quality evidence in children shows that a reduction in sodium intake reduces blood pressure.
"Lower sodium intake is also associated with a reduced risk of stroke and fatal coronary heart disease in adults. The totality of evidence suggests that most people will likely benefit from reducing sodium intake."