Vitamin D deficiency has been linked to an increased risk of endometriosis.[1] There is evidence that vitamin D may reduce inflammation and endometrial cell proliferation and may serve as a therapy for the treatment of endometriosis.[2] This study asked whether vitamin D supplementation improves symptoms and metabolic profiles in women with endometriosis.

The study

This 12-week randomized controlled trial enrolled 60 women (18–40 years old) with endometriosis. The participants were assigned to take either 50,000 IU of vitamin D or a placebo once every two weeks. The researchers collected blood samples at baseline and at the end of the intervention to measure various biochemicals. The primary outcomes were malondialdehyde (a marker of oxidative stress) and clinical symptoms. The secondary outcomes were metabolic profile measures.

The results

The results are based on the 50 participants who completed the trial. Vitamin D supplementation decreased pelvic pain and high-sensitivity C-reactive protein (a marker of inflammation), increased total antioxidant capacity, and improved the total-/HDL-cholesterol ratio. Malondialdehyde, metabolic profiles, and other symptoms were unchanged by supplementation.


This study was preregistered to report on depression as a secondary outcome, but this outcome was not included in the published article.

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This Study Summary was published on March 5, 2021.


  1. ^Yichao Qiu, Shuang Yuan, Hongjing WangVitamin D status in endometriosis: a systematic review and meta-analysisArch Gynecol Obstet.(2020 Jul)
  2. ^Mariko Miyashita, Kaori Koga, Gentaro Izumi, Fusako Sue, Tomoko Makabe, Ayumi Taguchi, Miwako Nagai, Yoko Urata, Masashi Takamura, Miyuki Harada, Tetsuya Hirata, Yasushi Hirota, Osamu Wada-Hiraike, Tomoyuki Fujii, Yutaka OsugaEffects of 1,25-Dihydroxy Vitamin D3 on EndometriosisJ Clin Endocrinol Metab.(2016 Jun)