Effect of sodium restriction on large artery stiffness and distensibility of small arteries in hypertensive patients: a randomized trial

Objective: Arterial stiffness is characterized by a decrease in arterial distensibility, resulting from the interaction between the extracellular matrix and cellular elements. Large and small arteries can be differently influenced by extrinsic factors, such as excessive sodium intake. This study aim to evaluate the impact of sodium restriction on large artery stiffness and distensibility of small arteries in young adults diagnosed with arterial hypertension. Methods: Randomized controlled clinical trial, including 20 hypertensive patients, aged between 30 and 59 years, followed up at the hypertension outpatient clinic of a tertiary hospital. Subjects were randomized into two groups: group 1 - low-sodium diet (2 g sodium/day); group 2 - usual diet. To analyze the stiffness and distensibility of the arteries, it was measured aortic pulse wave velocity by Complior®, elasticity of small arteries and vascular resistance by HDI®, and also through the measurement of metalloproteinase-9. For nutritional assessment it were considered blood glucose levels, 24-h urinary sodium, body mass index (BMI) and other anthropometric measurements. For nutritional intake we analized the 24-hour dietary recall. Results and Discussion: In comparison with group 2, it was observed a significant (p < 0.05) reduction in office blood pressure (p = 0,037) and pulse wave velocity (p = 0,010) in group 1 subjects. Also, in group 1 it occurred reduction in blood glucose levels, BMI, waist and neck circumference. Sodium intake was significantly reduced in group 1, taking into account 24 hs urinary sodium and evaluated by dietary recall. It is worth mentioning that excessive sodium intake linked to arterial hypertension causes a remodeling process, increased oxidative stress, inflammation and fibrosis of the arteries, contributing to arterial stiffness. Regarding the distensibility of small arteries, no significant differences were found between the two groups, but the intervention period and the number of individuals in the study should be taken into account, since these factors may have influenced the results. Conclusion: Sodium restriction for a short period of time promoted reduction of arterial stiffness, in parallel to reduction in obesity parameters and blood pressure in adults diagnosed with systemic arterial hypertension.