April 5 (UPI) -- A new study adds even more evidence to the old adage, "an apple a day keeps the doctor away. "
Researchers at the Keck School of Medicine at the University of Southern California found that foods rich in potassium, including many fruits and vegetables, may be key to lowering blood pressure.
High blood pressure, or hypertension, is a condition that affects more than 1 billion people worldwide. The World Health Organization, or WHO, estimates that hypertension is the cause of 51 percent of deaths due to stroke and 45 percent of deaths from heart disease.
Researchers studied the association between blood pressure and dietary sodium, potassium and the sodium-potassium ratio and found that higher dietary potassium was linked to lower blood pressure, regardless of sodium intake.
"Decreasing sodium intake is a well-established way to lower blood pressure," Alicia McDonough, professor of cell and neurobiology at the Keck School of Medicine, said in a press release. "But evidence suggests that increasing dietary potassium may have an equally important effect on hypertension."
High potassium intake lowers blood pressure by using sodium to keep close control of potassium levels in the blood critical to normal heart, nerve and muscle function.
"When dietary potassium is high, kidneys excrete more salt and water, which increases potassium excretion," McDonough said. "Eating a high potassium diet is like taking a diuretic."
A 2004 Institute of Medicine study recommended adults consume at least 4.7 grams of potassium a day to lower blood pressure, blunt the effects of dietary sodium and reduce the risk of kidney stones and bone loss.
As compared to the recommendation, diets these days often consist of processed foods with added salt that are usually low in potassium, the researchers say.
"If you eat a typical Western diet, your sodium intake is high and your potassium intake is low," McDonough said. "This significantly increases your changes of developing high blood pressure."
The study was published in the American Journal of Physiology.