Introduction:
Vitamin E has a major role in increasing nitric oxide (NO) and reducing lipoperoxidation progression through transition of reproductive age to post-menopause.Objective: This study aimed to determine the effect of vitamin E vs. placebo on plasma NO in menopausal women with hot flashes (HFs).Method: In a double-blind, randomized, cross-over clinical trial in a teaching hospital, 83 eligible menopausal women with HFs were randomly block allocated to vitamin E (n=42) and placebo (n=41) groups. In the phase І of the intervention, they were administered 400 IU per day vitamin E or placebo for 4 weeks. In the phase ΙΙ, group receiving vitamin E was subsequently given placebo and vice versa after wash-out. Primary outcomes were the number and severity of HFs per day determined by the recorded values by the women and using scaling of Modified Kupperman Index, respectively. Secondary outcome was plasma NO measured before and after the intervention in the two phases. Both outcomes analysed within and between placebo-vitamin E (P-E) and vitamin E-placebo (E-P) groups, and also in overall by gathering vitamin E and placebo groups in the two phases, separately. Data were analyzed using Chi-Square test, Independent t-test, Wilcoxon test, Mann-Whitney test, and Spearman correlation.Results: The mean of HFs number indicated a statistically significant decreasing trend from week ΙΙ of the phase Ι to the end of the phase ΙΙ within P-E and E-P groups than before the intervention. Median (IQR) of HFs number changes was 2.03 (2.57) in P-E group and was 1.21 (2.21) in E-P group in the end of week Ι of the phase ΙΙ (P=0.043). There was a very low significant positive correlation between the changes in HFs and plasma NO in week Ι (r=0.262, P=0.029) and week ΙΙ (r=0.256, P=0.034) in vitamin E group.Conclusion:
Vitamin E and placebo were both effective in reducing HFs in menopausal women. It seems that placebo subjective effect contributed to this decline.
Vitamin E had no effect on reducing HFs via affecting increase in plasma NO. These results were not in line with the expected hypothesis. Further research is needed to understand this issue.