title: Estimation of salt intake by urinary sodium excretion in a Portuguese adult population and its relationship to arterial stiffness.
abstract: BACKGROUND
  Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level.
  
  
  OBJECTIVE
  To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal.
  
  
  METHODS
  A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits.
  
  
  RESULTS
  We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable.
  
  
  CONCLUSIONS
  Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.
authors.affiliation: Faculdade das Ciências da Saúde da Universidade Fernando Pessoa, Porto, Portugal. jjpolonia@mail.telepac.pt
authors.forename: Jorge
authors.initials: J
authors.lastname: Polónia
authors.forename: João
authors.initials: J
authors.lastname: Maldonado
authors.forename: Rui
authors.initials: R
authors.lastname: Ramos
authors.forename: Susana
authors.initials: S
authors.lastname: Bertoquini
authors.forename: Mary
authors.initials: M
authors.lastname: Duro
authors.forename: Cristina
authors.initials: C
authors.lastname: Almeida
authors.forename: João
authors.initials: J
authors.lastname: Ferreira
authors.forename: Loide
authors.initials: L
authors.lastname: Barbosa
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Silva
authors.forename: Luís
authors.initials: L
authors.lastname: Martins
mesh_terms: D000328:Adult; D000368:Aged; D001158:Arteries / Q000503:physiopathology*; D001794:Blood Pressure; D003430:Cross-Sectional Studies; D004548:Elasticity; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011174:Portugal; D011674:Pulse; D012964:Sodium / Q000652:urine*; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
chemical_list: D017673:Sodium Chloride, Dietary; D012964:Sodium