ANTIOXIDANT VITAMINS SUPPLEMENTATION DURING 7-DAYS HIGH-SALT DIET PREVENTS IMPAIRMENT OF MICROVASCULAR RECTIVITY IN RESPONSE TO VASCULAR OCCLUSION IN YOUNG HEALTHY INDIVIDUALS

Abstract

Objective: Our earlier studies demonstrated that 7-days high-salt (HS) diet impairs vascular reactivity in forearm skin microcirculation, as well as increases level of oxidative stress in young healthy individuals, independently of arterial blood pressure (BP) changes. The aim of the present study was to test whether HS diet-induced increased oxidative stress have direct role in observed microvascular changes by functionally testing if antioxidant vitamins supplementation during 7-days HS diet will prevent impairment of microvascular reactivity in response to vascular occlusion in young healthy individuals. Design and method: 55 young healthy individuals participated in this study (27 men, 28 women, age ranged 18–26). All subjects took 7-days low-salt (LS) diet – washout period (<3.2 g salt/day) followed by 7-days HS diet (∼14 g salt/day) without (HS group) or with vitamin C (1000 mg/day) and E (800 IU/day) supplementation (HS+C+E group). Forearm skin microvascular reactivity in response to vascular occlusion - post-occlusive reactive hyperemia (PORH) was assessed by laser Doppler flowmetry (LDF) before and after diet protocols. BP and heart rate (HR) were measured at the beginning of each study visit. Compliance to the prescribed LS and HS diet was assessed by calculating salt intake from 24 h urinary sodium excretion. Results: There was no change in BP and HR after HS or HS+C+E protocol compared to LS. Changes in 24 h urinary sodium excretion confirmed that subjects conformed to the diet protocols. Consistent with our earlier results, PORH was significantly impaired in HS group (R-O% LS 135 ± 34 vs. HS 105 ± 19, P < 0.001). However, such impairment was not observed, and PORH was not changed in group taking antioxidant vitamins during HS diet (R-O% LS 133 ± 25 vs. HS+C+E 131 ± 27, P = 0.813). Conclusions: The results of the present study confirmed our previous findings that 7-days HS diet affects peripheral microvascular reactivity independently of BP changes, and for the first time demonstrated that antioxidant vitamins (C and E) supplementation during HS diet prevents microvascular function impairment in healthy individuals. These results indicate that increased level of oxidative stress level presents an important mechanism (and link) through which HS adversely affects vascular function in healthy normotensive individuals.