Vitamin D Supplementation Decreases TGF-β1 Bioavailability in PCOS: A Randomized Placebo-Controlled Trial

Context: There is an abnormal increase in TGF-β1 bioavailability in women with polycystic ovary syndrome (PCOS), which might play a role in the pathophysiology of this syndrome. Vitamin D (VD) supplementation improves various clinical manifestations of PCOS and decreases TGF-β1 levels in several diseases including myelofibrosis. Objective: The objective of the study was to determine the effect of VD supplementation on TGF-β1 bioavailability in VD-deficient women with PCOS and assess whether changes in TGF-β1/soluble endoglin (sENG) levels correlate with an improvement in PCOS clinical manifestations. Design: This was a prospective, randomized, placebo-controlled trial. Setting: The study was conducted at an academic-affiliated medical center. Participants: Sixty-eight VD-deficient women with PCOS who were not pregnant or taking any exogenous hormones were recruited between October 2013 and January 2015. Interventions: Forty-five women received 50 000 IU of oral vitamin D3 and 23 women received oral placeb...