EFFECT OF LOW-SODIUM DIET OR POTASSIUM SUPPLEMENTATION ON ADOLESCENT BLOOD-PRESSURE

The roots of essential hypertension extend back into the first two decades of life, suggesting that effective intervention during those years may lead to a reduction in the incidence of adult hypertension. Decreasing the dietary sodium/potassium ratio offers a potentially effective approach to blood pressure reduction. This study tested the feasibility of 3-year sodium reduction or potassium supplementation in adolescents and the effect of these interventions on the rate of rise of blood pressure during adolescence. After 19,452 5th to 8th grade students were screened, 210 from the upper 15 percentiles of blood pressure distribution (105 boys, 105 girls) were randomly assigned to one of three groups: low sodium diet (70 mmol sodium intake per day), potassium chloride supplementation (normal diet plus 1 mmol/kg potassium chloride per day), or placebo (normal diet plus placebo capsule). Capsules for the potassium chloride and placebo groups were administered in a double blind protocol. Blood pressure was measured every 3 months for 3 years. The effect of the intervention was determined by comparing the rate of rise (slope) of blood pressure among the groups using a random-coefficient growth curve model. The boys groups and the girls placebo group had similar positive blood pressure slopes that were significantly different from zero. The girls low sodium group had a slightly negative slope (significantly lower than the slope of the girls placebo group), and the girls potassium group had a slightly positive slope. Both of these slopes were not significantly different from zero and were significantly lower than the slopes of the respective boys groups. These results show that dietary sodium and potassium changes within the first two decades of life can reduce blood pressure in girls. Differences in blood pressure response between boys and girls suggest different sensitivities to supplemental potassium or dietary sodium change. The feasibility of long-term dietary sodium reduction in the United States, particularly in boys, is limited.