"There has been a lot of publicity about lowering salt or sodium in the diet in order to lower blood pressure, but not enough on increasing dietary potassium," said lead author Susan Hedayati, MD, of the University of Texas Southwestern Medical Center in Dallas, Texas, and the Dallas VA Medical Center.
The new study also identified a gene that may influence potassium's effects on blood pressure.
The researchers analyzed data on approximately 3,300 subjects from the Dallas Heart Study, about half of whom were African American. The results showed that the amount of potassium in urine samples was strongly related to blood pressure.
"The lower the potassium in the urine, hence the lower the potassium in the diet, the higher the blood pressure. This effect was even stronger than the effect of sodium on blood pressure," Hedayati said.
The relationship between low potassium and high blood pressure remained significant even when age, race, and other cardiovascular risk factors-including high cholesterol, diabetes, and smoking-were taken into account.
The new results provide important new data on the relationship between potassium and blood pressure in a sample that was 50 percent African American.
"Our study included a high percentage of African-Americans, who are known to consume the lowest amounts of potassium in the diet," Hedayati said.
The researchers also found evidence that a specific gene, called WNK1, may be responsible for potassium's effects on blood pressure.
"We are currently doing more research to test how low potassium in the diet affects blood pressure through the activity of this gene," Hedayati said.
The study is being presented at the American Society of Nephrology's 41st Annual Meeting and Scientific Exposition in Philadelphia, Pennsylvania.