PP.38.23

Abstract

Objective: High sodium intake and obesity are recognized as risk factors for hypertension in children as well as in adults. The effect of sodium intake on blood pressure (BP) might be modified by the presence of obesity and metabolic disorders. We therefore assessed the association between usual dietary sodium intake and BP by weight status in healthy adolescents. Design and method: A total of 245 adolescents (112 males and 135 females), aged between 12 and 15 years, was examined in this study. They had no history of treatment for hypertension, syndromal obesity, diabetes mellitus, dyslipidemia, or renal disease. Blood pressure was measured in the supine position using digital BP monitor with an appropriate size cuff. The 24-hour urine sodium excretion level was estimated by the sodium and creatinine concentrations of two nonconsecutive spot urine specimens collected in the early morning. Results: The sodium intake of participants increased with age and was significantly higher in males than in females (7.9 ± 2.3 g/day vs. 7.2 ± 1.9 g/day, p = 0.005). The sodium intake was significantly correlated with body height, weight, and BMI in both males and females. There was a significant association between sodium intake and systolic BP (β = 0.131, p = 0.042) as well as pulse pressure (β = 0.168, p = 0.008) after adjusting for age, gender, and height. An increase of 1 g/day in the sodium intake was related to an increase of 0.4mmHg in systolic BP and 0.5mmHg in pulse pressure. There were graded associations of the weight status with systolic BP and pulse pressure (p for trend <0.001). In multivariate regression analysis, the effect of sodium intake on systolic BP was decreased and not statistically significant (β = 0.045, p = 0.514) when BMI was entered in the model as an explanatory variable. However, in the additive model to estimate the interaction of sodium intake and weight status, higher sodium intake and greater body weight were found to have synergistic effects on the increase in systolic BP (β = 0.161, p = 0.019). Conclusions: The higher sodium intake is associated with increased systolic BP among healthy adolescents, and this association may be greater in subjects who are overweight or obese than those who are normal weight.