4. Discussion
peripheral muscular arteries [Impaired FMD, hypertension, prediabetes
OXIDATIVE STRESS, HYPERTENSION, PREDIABETES, OXIDATIVE STRESS
This study examined the effects of 4 weeks of CIT and CIT+GSH supplementation on vascular function and BP responsiveness in healthy postmenopausal women. We found that CIT+GSH supplementation improved endothelial function through an increase in the ARG/ADMA ratio. Although CIT supplementation increased serum ARG levels and the ARG/ADMA ratio, it did not statistically improve FMD. In addition, CIT+GSH supplementation attenuated BP responsiveness to CPT. These data show that CIT+GSH supplementation has protective cardiovascular effects at rest and during sympathetic stimulation (CPT) in healthy postmenopausal women.FMD decreases progressively throughout the stages of the menopausal transition in healthy women [Recent data showed that FMD values lower than 5.4% are indicative of impaired endothelial function in apparently healthy adults [Age associated arterial stiffening affects the aorta to a greater extent than peripheral muscular arteries [Impaired FMD and increased sympathetic activity are associated with the increased risk of incident hypertension in healthy postmenopausal women [ADMA competes with ARG for binding to eNOS, thereby a decrease in ARG/ADMA leads to reduced NO production [Despite greater increases in the serum ARG levels and ARG/ADMA ratio, FMD did not improve after CIT supplementation alone. This discrepancy in the findings may be explained by the healthy status of the participants. In agreement with our findings, ARG supplementation for 4 weeks increased serum ARG levels by almost double but failed to improve FMD in healthy postmenopausal women [Oxidative stress markers were not improved by both supplementations. In healthy adults, 200–1000 mg of GSH daily for 4 weeks did not improve microvascular endothelial function and malondialdehyde levels [There are some limitations in the present study. The sample size was relatively small and included healthy postmenopausal women. FBG was not considered for randomization, which resulted to be higher in the CIT+GSH group. Future studies might investigate the effects of CIT and CIT+GSH in individuals with prediabetes. A GSH dose greater than 200 mg daily for longer than 4 weeks of supplementation may reduce markers of oxidative stress, as previously shown [