Potassium shortage joins sodium excess as a top risk factor for high blood pressure; Imbalance impacts African Americans more strongly
by Craig Weatherby
Everyone’s heard that eating excess sodium can raise blood pressure, especially in genetically susceptible people.
But new findings suggest that getting too little potassium exerts equally unhealthful effect pressure-raising effects.
Since bananas are one of the best sources of this elemental nutrient, it makes sense to emulate our primate friend at left ... or take daily potassium pills.
The news comes from research presented at the American Society of Nephrology's 41st Annual Meeting in Philadelphia (Hedayati S et al. 2008).
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.
And the negative impact of low potassium intake appears especially strong among African Americans.
They analyzed data collected from about 3,300 people – about half of whom were African American – participating in the Dallas Heart Study.
The results showed that the amount of potassium in urine samples was strongly related to blood pressure. People whose reported diets were low in potassium also showed lower potassium levels in their urine and higher blood pressure.
Importantly, this effect was even stronger than the effect of sodium on blood pressure.
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.
Findings support prior indications and adds a genetic factor
Previous studies, including the large Dietary Approaches to Stop Hypertension (DASH) study, 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 percent African American.
The study included a high percentage of African-Americans, who are known to consume the lowest amounts of potassium in the diet.
The authors of the study also identified a possible genetic factor in potassium’s effects on blood pressure.
Related research led by co-author Chou-Long Huang, M.D. found evidence that a specific gene called WNK1 may govern dietary potassium’s effects on blood pressure.
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 the activity of the WNK1 gene is measured in participants consuming diets containing fixed amounts of fixed potassium, to see if WNK1 is responsible for the potassium-pressure link.
The Dallas team urged people to get more potassium and less sodium.
High-potassium foods include bananas, citrus fruits, and vegetables.
Hedayati S, Minhajuddin A, Moe OW, Huang CL, et al. Dietary Potassium Deficiency Is Independently Associated with Increased Blood Pressure in a Multi-Ethnic Population-Based Cohort. (SA-FC404). Presented Saturday, November 8, 2008 at the American Society of Nephrology (ASN) 41st Annual Meeting and Scientific Exposition in Philadelphia, PA.