There is a clear relationship between sodium intake and peripheral blood pressure (BP), both in adults and in adolescents. Less is known on the relationship between sodium consumption and central BP and the main dietary sources of daily sodium intake in adolescence. We aimed at evaluating sodium intake and its links with central and peripheral BP in a population of Italian adolescents.Design and method:
401 healthy adolescents aged 17 ± 1 years (58% boys, average brachial/central BP: 124/67 ± 11/7 mmHg, and 105/69 ± 9/8 mmHg), attending the Liceo Donatelli High School, Terni, Italy, were evaluated. Daily sodium intake was estimated from a single fasting second-void urine by a previously-validated formula (Tanaka). Main sources of daily sodium intake were investigated by a self-administered food frequency questionnaire (Project Big-Life). Central BP was estimated by radial and brachial applanation tonometries, and calibrated to brachial MAP/DBP (SphygmoCor).Results:
24-h estimated urinary sodium (24-hUNa) was 135 ± 30 mmol/d (3.116 g/d), and was higher in boys than in girls (139 ± 30 vs 130 ± 31 mmol/d, p = 0.004). 89% of the population showed excess sodium intake according to international guidelines. 24-hUNa was directly correlated to brachial and central SBP (ρ = 0.14 and ρ = 0.15, both p < 0.01), to brachial and central PP (ρ = 0.19 and ρ = 0.24, both p < 0.01), and to central-to-peripheral PP amplification (ρ = −0.13, p < 0.01), but not to central-to-peripheral SBP amplification (ρ = −0.01, p = 0.85). In a fully-adjusted multivariate regression model, 24-hUNa (β=0.10, p = 0.04) was independently related to central-to-peripheral PP amplification, but not to other measures of both peripheral and central BP. In a factorial analysis, the main daily dietary sources of sodium were bread, biscuits, and salt added to foods (41% of the total estimated sodium intake).Conclusions:
Current salt intake is unnecessarily high in Italian adolescents. Sodium intake has a direct relationship with both central and peripheral SBP and PP, and shows an independent association with central-to-peripheral PP amplification. The adverse effects of an excess of sodium intake are more pronounced in central than in peripheral PP. Interventions aiming at reducing sodium intake may ultimately have a favorable impact on the cardiovascular health among adolescents through a reduction of central PP.