Association of 24-h Urinary Salt Excretion with Central Haemodynamics and Assessment of Food Categories Contributing to Salt Consumption in Portuguese Patients with Hypertension

Objective: High salt intake has been associated with the development of arterial hypertension, but it still remains controversial as to how salt consumption relates with central haemodynamics and central pressures. For interventional purposes, it is crucial to identify the main food categories that contribute toward high salt consumption.

Methods: In 638 Caucasian hypertensive patients (age 50±15 years, 329 women) enrolled for 7 years, we evaluate the independent relationship between urinary sodium (UNa, mean 207±78 mEq/24 h) or potassium (UK, mean 79±26 mEq/24 h) excretion measured in validated 24-h samples and office blood pressure (BP), 24 h BP, central pulse pressure, and parameters of central pulse wave analysis. A subgroup (n=154) of this population (UNa, mean 205±75 mEq/24 h) was also subjected to structured validated food frequency questionnaires on dietary habits.

Results: Multiple regression analysis showed that UNa was associated independently with increases in 24-h systolic BP, central pulse pressure, and augmented aortic augmentation index (AIx) and associated inversely with pulse pressure amplification. In the subgroup, patients of the upper tercile of distribution of UNa (288±21 mEq/24 h) ate significantly higher amounts (g/day) of vegetables, sauces, bread, cheese, fries and sausages/cold meat, yielding an estimation that bread could account for 20-27% of all daily salt intake.

Conclusion: Reduction of salt intake on the basis of the main food sources that we have identified could also influence cardiovascular risk throughout effects on 24-h and central pressures.