METHODS AND RESULTS: We conducted an observational study to investigate whether
dietary sodium intake predicts future blood pressure and the onset of
hypertension in the general population. Individual
sodium intake was estimated by calculating 24-hour urinary
sodium excretion from spot urine in 4523 normotensive participants who visited our hospital for a health checkup. After a baseline examination, they were followed for a median of 1143 days, with the end point being development of
hypertension. During the follow-up period,
hypertension developed in 1027 participants (22.7%). The risk of developing
hypertension was higher in those with higher rather than lower
sodium intake (hazard ratio 1.25, 95% CI 1.04 to 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.