Salt restriction not effective intervention for lowering 24-hour BP variability in White population

Netherlands: A recent study revealed that salt restriction is not an effective strategy to lower blood pressure variability as Urinary sodium excretion and salt intake are not independently associated with 24‐hour BPV. The study results were published in the Journal of the American Heart Association. 

Blood pressure variability (BPV) has been associated with cardiovascular disease and mortality. Studies in the past have shown that higher salt intake may cause arterial stiffness thus causing greater BPV. Research has shown inconsistent results on the association between urinary sodium excretion and salt intake on BPV. Hence Tan Lai Zhou et al from the Netherlands have conducted a study in the observational population‐based Maastricht Study and a randomized crossover trial with low‐ and high‐salt diets, whether higher 24‐hour urinary sodium excretion and increased salt intake are associated with greater 24‐hour BPV. 

The study was carried out using data from the cross‐sectional population‐based Maastricht Study having 2652 participants aged 60±8 years (52% men) and from a randomized crossover trial having 40 participants aged 49±11 years (33% men). 24‐hour urinary sodium excretion and 24‐hour BPV were measured in the observational study. Linear regression analysis adjusted for age, sex, mean blood pressure, lifestyle, and cardiovascular risk factors was done. In the intervention study, participants adhered to a 7‐day low‐ and high‐salt diet (50 and 250 mmol NaCl/24 h) with a washout period of 14 days, 24‐hour BPV was measured during each diet. Linear mixed models adjusted for order of diet, mean blood pressure, and body mass index were used.

Key findings of the study:

• There was no association between the 24‐hour urinary sodium excretion and 24‐hour systolic or diastolic BPV in the observational study (β, per 1 g/24 h urinary sodium excretion: 0.05 mm Hg and 0.04 mm Hg, respectively).
• There was no statistically significant difference between the mean difference in 24‐hour systolic and diastolic BPV between the low‐ and high‐salt diet in the intervention trial (0.62 mm Hg and 0.04 mm Hg, respectively). 

Thus, there was no association of urinary sodium excretion and salt intake with 24‐hour BPV independently. 

Further reading: Zhou TL, Schütten MTJ, Kroon AA, et al. Urinary Sodium Excretion and Salt Intake Are Not Associated With Blood Pressure Variability in a White General Population. J Am Heart Assoc. 2023;12(1):e026578. doi:10.1161/JAHA.122.026578