Association between sodium excretion and hydration status by Free Water Reserve: a cross-sectional analysis in adolescents

Are older adults with excessive sodium intake at increased risk of hypohydration?

BACKGROUND

Sodium intake is expected to affect water needs, although compensation mechanisms may not work efficiently particularly in older adults. The aim of this cross-sectional study was to quantify the association between sodium excretion and hydration status in a representative sample of Portuguese older adults.

METHODS

A cluster sampling approach was used, representing Portuguese older adults (≥65 years) according to sex, education level and region. From a sample size of 1500 participants, 1318 were eligible for the present analysis. A 24-h urine sample was collected, and volume, osmolality, creatinine and sodium were quantified. Free water reserve (FWR) was used to assess hydration status. Excessive sodium intake was defined as above 2000 mg day^-1 as recommended by the World Health Organization. A multivariable binary logistic regression model was used to estimate the association between FWR and sodium excretion. Odds ratios (OR) and respective 95% confidence intervals (95% CI) were calculated.

RESULTS

Excessive sodium excretion was observed in 80.0% of women and 91.5% of men, whereas hypohydration affected 10.9% of women and 23.6% of men. After adjusting for confounders, excessive sodium excretion was associated with an increased risk of hypohydration among men (OR = 2.75; 95% CI = 1.06-7.15).

CONCLUSIONS

These results stress the positive association between excessive sodium intake and hypohydration in men and highlight the need for implementing strategies regarding the reduction of salt consumption and the promotion of water intake.

Innovative equipment to monitor and control salt usage when cooking at home: iMC SALT research protocol for a randomised controlled trial

INTRODUCTION

Excessive salt intake is a public health concern due to its deleterious impact on health. Most of the salt consumed come from those that are added when cooking. This study will improve knowledge on the effectiveness of interventions to reduce salt consumption among consumers.

METHODS AND ANALYSIS

In this randomised clinical trial, we will be evaluating the efficacy of an intervention-the Salt Control H, an innovative prototype equipment to monitor and control use of salt when cooking-among workers from a public university, with the aim of reducing their dietary salt intake. We will randomly select 260 workers who meet the eligibility criteria and who are enrolled to an occupational health appointment and randomise them into one of the two arms of the study (either control or intervention), with matched baseline characteristics (sex and hypertension). The intervention will last for 8 weeks, during which the participants will use the equipment at home to monitor and control their use of salt when cooking. The main outcome will be 24-hour urinary sodium excretion at baseline, at fourth and eighth weeks of intervention, and at 6 months after intervention.

ETHICS AND DISSEMINATION

Ethical approval for the study has been obtained from the Ethics Committee of the Centro Hospitalar Universitário São João. The results of the investigation will be published in peer-reviewed scientific papers and presented at international conferences.

TRIAL REGISTRATION NUMBER

NCT03974477 EQUIPMENT PROVISIONAL PATENT NUMBER: Registered at INPI: 20191000033265.