As a risk factor for high blood pressure, low levels of potassium
in the diet may be as important as high levels of sodium-especially
among African Americans, according to research being presented
at the American Society of Nephrology's 41st Annual Meeting
and Scientific Exposition in Philadelphia, Pennsylvania.
"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," comments 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 suggests that low potassium may be a
particularly important contributor to high blood pressure
among African Americans, and also identifies 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," says Dr. Hedayati.
"This effect was even stronger than the effect of sodium on
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.
Previous studies, including the landmark "Dietary Approaches
to Stop Hypertension" study (DASH), have linked potassium
deficiency to high blood pressure. The new results support
this conclusion, and provide important new data on the relationship
between potassium and blood pressure in a sample that was
50% African American. "Our study included a high percentage
of African-Americans, who are known to consume the lowest
amounts of potassium in the diet," according to Dr. Hedayati.
Research performed in the laboratory of Dr. Chou-Long Huang,
a co-author of this study, has 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," adds Dr. Hedayati.
The conclusions are limited by the fact that people in the
Dallas Heart Study weren't following any specific diet. The
researchers are currently performing a study in which participants
are on fixed potassium diets while measuring the activity
of the WNK1 gene to see if WNK1 is responsible for this phenomenon.
Meanwhile, they urge efforts to increase the amount of potassium
in the diet, as well as lowering sodium. "High-potassium foods
include fruits such as bananas and citrus fruits and vegetables,"
says Dr, Hedayati. "Consuming a larger amount of these foods
in the diet may lower blood pressure."