Vitamin C and E antioxidant supplementation may significantly reduce pain symptoms in endometriosis: A systematic review and meta-analysis of randomized controlled trials

Background The primary challenge encountered by individuals diagnosed with endometriosis is the experience of pain. Emerging research indicates that oxidative stress is implicated in the initiation of pain associated with endometriosis. Vitamins C and E are known for their antioxidative properties. The primary objective of this study is to assess the efficacy of antioxidant supplementation, consisting of these vitamins, in the management of pain associated with endometriosis. Methods A comprehensive search was conducted on the ClinicalTrials.gov, Scopus, Europe PMC, and Medline databases up until August 23(rd), 2023, utilizing a combination of relevant keywords. This review incorporates literature that examines the relationship between antioxidant supplementation and pain in endometriosis. We employed fixed-effect models to analyze the risk ratio (RR) and present the outcomes together with their corresponding 95% confidence intervals (CI). Results A total of five RCTs were incorporated. The results of our meta-analysis indicated that antioxidant supplementation with vitamin C and E combination was associated with higher proportion of endometriosis patients reporting reduced chronic pelvic pain (RR 7.30; 95%CI: 3.27-16.31, p<0.00001, I-2 = 0%), alleviations of dysmenorrhea (RR 1.96; 95%CI: 1.25-3.07, p = 0.003, I-2 = 39%), and dyspareunia (RR 5.08; 95%CI: 2.10-12.26, p = 0.0003, I-2 = 0%) than patients only receiving placebo. Conclusions This study suggests the potential ability of vitamin C and E in alleviating pain symptoms experienced by individuals with endometriosis.