The Effect of 7-Day High-Salt Diet on Serum Antioxidant Enzymes Protein Concentrations: Does Antioxidant Vitamins Supplementation Matter?

Abstract

Objective: It is well documented that high salt (HS) diet causes increased oxidative stress. Present study aimed to test the effect of 7-day HS diet on serum protein concentrations of Cu/Zn superoxide dismutase (Cu/Zn SOD), glutathione peroxidase 1 (GPx1) and catalase, and to examine whether the oral supplementation of non-specific ROS scavengers (vitamin C and vitamin E) during 7-day HS loading will change serum protein concentrations of these antioxidant enzymes in otherwise healthy normotensive individuals. Design and method: 40 young healthy individuals (20 men and 20 women, age ranged 18–24) were assigned to a 7-day low-salt diet (<3.5 g salt/day) followed by a 7-day HS diet (∼14 g salt/day) without (HS group) or with the daily supplementation of vitamins C (1000 mg) and E (800 IU) (HS + C + E group). Blood pressure (BP) and heart rate (HR) were measured at each study visit. Serum protein concentrations of Cu/Zn SOD, GPx1 and catalase were measured by commercially available ELISA kits before and after diet protocols. Results: BP and HR were not significantly different in both, HS and HS + C + E groups compared to LS diet. Changes in calculated daily salt intake from 24 h sodium excretion confirmed that participants conformed to the diet protocols. Serum protein concentration of Cu/Zn SOD and GPx1 were not significantly changed following both HS or HS + C + E diet compared to measurement following LS diet. 7-day HS diet significantly decreased serum catalase concentration in HS group compared to LS diet (catalase pg/ml LS 347 ± 495 vs. HS 261 ± 462, P < 0.05), while catalase concentration was similar after LS and following 7 days of HS + C + E diet (catalase pg/ml LS 249 ± 375 vs. HS + C + E 186 ± 349, P > 0.05). Conclusions: The results of this study suggest that disturbing the activity of antioxidative defense itself (decreased serum catalase concentration) could potentially contribute to the altered oxidative status in healthy individuals on a HS diet, which could be prevented by intake of antioxidant vitamins C and E during HS diet.