British Journal of Nutrition

Dietary Surveys and Nutritional Epidemiology

Estimation of salt intake by 24 h urinary sodium excretion in a representative sample of Spanish adults

Rosa M. Ortegaa1 c1, Ana M. López-Sobalera1, Juan M. Ballesterosa2, Napoleón Pérez-Farinósa2, Elena Rodríguez-Rodrígueza1, Aránzazu Aparicioa1, José M. Pereaa1 and Pedro Andrésa3

a1 Departamento de Nutrición, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain

a2 Agencia Española de Seguridad Alimentaria y Nutrición (AESAN), Ministerio de Sanidad y Política Social, c/Alcalá 56, 28071 Madrid, Spain

a3 Laboratorio de Técnicas Instrumentales, Sección Departamental de Química Analítica, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain

Abstract

The present study reports the Na intake of a representative sample of Spanish young and middle-aged adults aged 18–60 years (n 418, 53·1 % women, selected from the capitals of fifteen provinces and the surrounding semi-urban/rural area), measured with a 24 h urinary Na excretion method. To validate the paper collection of 24 h urine, the correlation between fat-free mass determined by electrical bioimpedance (50·8 (sd 11·3) kg) and that determined via urinary creatinine excretion (51·5 (sd 18·8) kg) was calculated (r 0·633, P < 0·001). Urinary Na excretion correlated with systolic and dyastolic blood pressure data (r 0·243 and 0·153, respectively). Assuming that all urinary Na (168·0 (sd 78·6) mmol/d) comes from the diet, Na excretion would correspond with a dietary salt intake of 9·8 (sd 4·6) g/d, and it would mean that 88·2 % of the subjects had salt intakes above the recommended 5 g/d. Logistic regression analysis, adjusted for sex, age and BMI, showed male sex (OR 3·678, 95 % CI 2·336, 5·791) and increasing BMI (OR 1·069, 95 % CI 1·009, 1·132) (P < 0·001) to be associated with excreting >200 mmol/d urinary Na – a consequence of the higher salt intake in men and in participants with higher BMI. The present results help us to know the baseline salt intake in the Spanish young and middle-aged adult population, and can be used as the baseline to design policies to reduce salt consumption.

(Received April 23 2009)

(Revised September 06 2010)

(Accepted September 09 2010)

(Online publication October 25 2010)

Correspondence:

c1 Corresponding author: Professor Rosa M. Ortega, fax +34 91 394 18 10, email rortega@farm.ucm.es

Footnotes

†  Research group: 920030.

Abbreviations: Q, quintile

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