Dietary Sodium Intake Predicts Future Hypertension

Study Questions:

Does relatively high dietary sodium intake increase the risk of developing hypertension compared with those with relatively low dietary sodium intake?

Methods:

An observational study was conducted in a general population in Japan undergoing health exams. Individual sodium intake was estimated by calculating 24-hour urinary sodium excretion from spot urine in 4,523 normotensive participants. Patients were followed for a median of 1,143 days, with the endpoint being development of hypertension.

Results:

Follow-up rate was 86.4%; 64% were male; mean age was 54.1 years, and age range was 22-85 years. Sodium intake was significantly higher in men than in women (4.7 ± 1.2 vs. 3.3 ± 0.8 g/day, respectively; p < 0.001). During the follow-up period, hypertension developed in 1,027 participants (22.7%). Mean yearly increase in systolic blood pressure was 6.2 mm Hg in those who developed hypertension versus -0.2 mm Hg in those who did not (p < 0.001), with yearly increase in sodium intake 0.11 versus 0.02 (p < 0.001). The risk of developing hypertension was higher in those with higher rather than lower sodium intake (hazard ratio, 1.25; 95% confidence interval, 1.04-1.50). In multivariate Cox proportional hazards regression analysis, baseline sodium intake and the yearly change in sodium intake during the follow-up period (as continuous variables) correlated with the incidence of hypertension. Furthermore, both the yearly increase in sodium intake and baseline sodium intake showed significant correlations with the yearly increase in systolic blood pressure in multivariate regression analysis after adjustment for possible risk factors.

Conclusions:

Both relatively high levels of dietary sodium intake and gradual increases in dietary sodium are associated with future increases in blood pressure and the incidence of hypertension in the Japanese general population.

Perspective:

High intake of dietary salt and salt sensitivity has been shown to accelerate or contribute to the development of hypertension in population studies. This large longitudinal study was conducted to provide further convincing evidence that salt intake increases the development of hypertension over time, which could influence sodium intake in the population. The data support that hypothesis.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention, Hypertension

Keywords: Blood Pressure Determination, Blood Pressure, Hypertension, Incidence, Metabolic Syndrome X, Primary Prevention, Risk Factors, Sodium, Sodium, Dietary


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