Blood pressure response to dietary sodium is reproducible over long term

Blood pressure (BP) response to changes in dietary sodium and potassium is reproducible over the long term and may help identify potential candidates at risk for hypertension and cardiovascular disease, according to a study published in the journal Hypertension.

The investigators tested and retested BP responses to changes in dietary sodium and potassium intake in 487 Chinese study participants over a four- to five-year period. Previous clinical studies had examined the reproducibility of BP responses to only dietary sodium change over the short term, and the results were not consistent.

“To the best of our knowledge, this is the first study to investigate the long-term reproducibility of salt sensitivity and potassium sensitivity of BP,” noted Dongfeng Gu, from the Department of Population Genetics and Prevention, Fu Wai Hospital and Cardiovascular Institute, Beijing, China, and colleagues.

The study

During the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study, approximately 1,800 individuals between the ages of 18 and 60 years in rural northern China completed the initial three-week dietary sodium and potassium interventions during October 2003 and July 2005. In the follow-up, 487 participants were retested about four and a half years later.

The dietary interventions were the same for the initial part of the study and the follow-up. After the three-day baseline observation period, participants adhered to a low-salt diet for seven days (3 g of salt or 51.3 mmol of sodium daily) and then a high-salt diet for another seven days (18 g of salt or 307.8 mmol of sodium per day). In the final week, daily potassium supplementation (60-mmol potassium) was added to the high-salt diet.

During the observation period and the interventions on days 5, 6, and 7 in the initial study and follow-up study, BP measurements were taken nine times at each intervention for a mean BP level. Compliance was validated with urinalysis.

Results

The results indicated that BP levels declined from baseline during the low-salt diet, increased during the high-salt diet, and declined during the high-salt diet and daily potassium supplementation for the participants in the initial and follow-up study.

“BP responses to changes in dietary sodium and potassium are not random phenomena but stable and reproducible human characteristics over a relatively long time period,” Dr. Gu and colleagues said.

“These findings have potentially important clinical and public health implications. High dietary sodium intake is a major risk factor for hypertension. Population-based sodium reduction should be complemented by targeted sodium reduction among individuals who are more sensitive to sodium intake,” they said.

The authors suggested that future studies should focus on the identification of simple biomarkers for classifying sodium and potassium sensitivity in humans. By identifying individuals with sensitivity to sodium and/or potassium, it may help with risk prediction and treatment of hypertension and cardiovascular diseases.