The effects of vitamin E on the intensity of primary dysmenorrhea: A systematic review and meta-analysis

Background & aims: Primary dysmenorrhea (PD) refers to the presence of painful menstrual cramps due to increased synthesis of prostaglandins. Vitamin E inhibits the release of arachidonic acid and its conversion to prostaglandins through its antioxidant properties. This study sought to examine the effects of oral vitamin E supplementation on PD intensity (primary outcome) and its side effects (secondary outcomes). Methods: In this systematic review and meta-analysis, databases in English and Persian, including PubMed, Cochrane Library, Google Scholar, Scopus, Web of Science, SID, and Magiran, were systematically searched until August 30, 2021. The study included all randomized, controlled clinical trials comparing oral vitamin E to placebo in healthy women with PD and measuring PD severity as a primary or secondary outcome. The quality of the included articles was assessed using the Cochrane Handbook, and the meta-analysis was performed using RevMan software. Given the continuous nature of the data and the utilization of different tools in the extracted articles, the meta-analysis results were reported using standardized mean difference (SDM) and 95% confidence interval (95% CI). A subgroup analysis was performed in low-dose (100 units), moderate-dose (200 units), and high-dose (400 units) categories. The quality of evidence was examined according to the GRADE approach. Results: Eight articles with a sample size of 1002 people were entered into this systematic review. The results of meta-analysis revealed that vitamin E consumption significantly reduced PD mean intensity in the first month (n = 7 records; SDM = -1.16; 95%CI: -2.16 to -0.17; I-2 = 31.9%; P = 0.02) and the second month (n = 8 records; SDM = -1.83; 95%CI: -2.90 to -0.77; I-2 = 76.3.9%; P < 0.0001) compared with placebo. Serious side effects were not reported in vitamin E recipients. Conclusion: Vitamin E could be an adjunctive treatment for women with PD. However, higher-quality clinical trials with larger sample sizes are recommended for a more definite conclusion. Prospero id: CRD42021276609. (c) 2022 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study examined the effects of oral vitamin E supplementation on primary dysmenorrhea (PD) intensity. The results showed that vitamin E consumption significantly reduced PD mean intensity in the first and second month compared with placebo, and no serious side effects were reported in vitamin E recipients. However, higher-quality clinical trials with larger sample sizes are recommended for a more definite conclusion.