The review found that in subgroup analyses, Vitamin E supplementation, with or without Vitamin C, had a positive effect improving clinical pelvic pain.
For painful menstrual periods known as dysmenorrhea, various vitamin supplementation of Vitamin C, D and E had a significant result in reducing pain.
For painful intercourse known as dyspareunia, combined Vitamin C and E supplementation showed significant relief but no significant difference to combined placebo and Vitamin D or only Vitamin E supplementation.
The researchers highlighted the lack of consistency in the different vitamin supplements used to reduce endometriosis pain, and cautioned about the confidence in the results due to the small number of research articles reviewed.
Mechanism at work
The review attributed the key factor of endometriosis pathophysiology to be due to oxidative stress that can worsen inflammation.
“Cells possess an antioxidant system to counteract the effects of ROS and maintain a balance between antioxidant defense and ROS production, thus preventing ROS-induced cellular damage and facilitating repair.
“Therefore, increasing antioxidant levels may help reduce endometriosis-related pathology caused by oxidative damage.”
The oxidative stress hypothesis was also verified in other studies that found lower serum levels of vitamins A, C and E compared to control groups in endometriosis patients.
Previous research has elicited the effectiveness of antioxidant food sources such as garlic extract, citrus fruits, as well as vitamins supplementation in reducing pain and lowering risk of endometriosis.
The researchers explained how vitamin supplementation helps to regulate inflammatory response by tackling oxidative stress markers: “Antioxidant treatment, including vitamin E and vitamin C, can effectively downregulate or inhibit inflammatory markers, such as interleukins 1 and 6 and monocyte chemotactic protein-1, which may contribute to the release of pain-inducing molecules.
“Vitamin E also exerts anti-inflammatory effects by inhibiting prostaglandin E2 production from arachidonic acid through a decline in cyclooxygenase activity.”
The researchers analysed 13 articles after filtering through 4420 articles from an electronic database search from inception up to 16th March 2023.
The electronic databases spanned Web of Science, PubMed, Cochrane Library, Scopus, and China National Knowledge Infrastructure (CNKI), and the studies originated from Iran, China, Mexico, Germany, Egypt, United States, and Atlanta.
The primary outcomes analysed include the relationship between vitamin supplementation and endometriosis-related chronic pelvic pain, endometriosis-related dysmenorrhea, endometriosis-related dyspareunia.
The secondary outcome analysed being the effect of vitamin supplementation on peripheral oxidative stress markers in endometriosis.
“Our study demonstrates that the use of antioxidant vitamins supplementation is generally effective in reducing endometriosis-related pain and inflammatory markers. Consequently, this therapy can be considered as an alternative treatment either on its own or in combination with other methods for managing endometriosis-related pain.
“However, considering the limited sample size and quality of the studies, further research is needed to provide a clearer understanding of the role of antioxidant vitamins supplementation in women with endometriosis. We also propose a future meta-analysis when new and similar studies are added to the literature,” the researchers concluded.
Source: Reproductive Biology and Endocrinology
“Antioxidant vitamins supplementation reduce endometriosis related pelvic pain in humans: a systematic review and meta-analysis”
Authors: Zheng, SH., et al.