Therapeutic Effects of Vitamins in Endometriosis Patients: A Systematic Review of Randomized Controlled Trials

Endometriosis is a chronic, estrogen-dependent inflammatory condition affecting approximately 10% of women of reproductive age worldwide. It is characterized by the presence of endometrial-like tissue outside the uterine cavity, which frequently results in dysmenorrhea, chronic pelvic pain, dyspareunia, and infertility. While hormonal medications and surgical procedures are common treatments, they are often constrained by adverse effects and high recurrence rates. The aim was to systematically identify, critically appraise, and synthesize randomized controlled trials evaluating vitamin D, C, and E supplementation in women with endometriosis, focusing on their effects on pelvic pain, dysmenorrhea, dyspareunia, quality of life, oxidative and inflammatory biomarkers, and fertility-related outcomes, and to highlight methodological gaps that can inform future research and integrated therapeutic strategies. Following PRISMA guidelines, seven eligible RCTs were identified from databases including PubMed, Scopus, and ScienceDirect. The quality of these studies was assessed using the Jadad Scoring System and Cochrane RoB 2 tool. High-dose supplementation of vitamin D (50,000 IU) was found to significantly reduce pelvic pain and improve biochemical markers such as hs-CRP and total antioxidant capacity (TAC). Vitamin D appears to modulate endometrial pathways by reducing active β-catenin protein activity, which may disrupt signaling associated with lesion invasion and survival. Additionally, combined Vitamin C and E therapy (typically 1000 mg/day of Vitamin C and 800 IU/day of Vitamin E) acts synergistically to scavenge free radicals. This intervention significantly decreased oxidative stress markers, including malondialdehyde (MDA) and reactive oxygen species (ROS). Patients reported significant improvements in symptoms, including a 43% reduction in daily pelvic pain and a 37% reduction in dysmenorrhea. Despite physiological improvements, there was no statistically significant increase in pregnancy rates observed across the trials. Vitamin supplementation with D, C, and E represents a safe, low-cost adjunct therapy that can effectively mitigate endometriosis-related oxidative stress and pelvic pain. While these vitamins show promise for symptom relief, further research with larger sample sizes is required to determine their long-term impact on fertility outcomes and lesion regression.