Vitamin D and reproductive disorders: a comprehensive review with a focus on endometriosis

Abstract

Vitamin D is a fat-soluble steroid hormone that was initially known only for regulating calcium and phosphorus levels and maintaining bone health. However, it was later discovered that many organs express vitamin D metabolizing enzymes and have a ligand for vitamin D, which regulates the expression of an extensive assortment of genes. As a result, vitamin D is indispensable for the proper function of organs, and its deficiency is believed to be a critical factor in symptoms and disorders such as cardiovascular diseases, autoimmune diseases, and cancers. The significance of vitamin D in reproductive tissues was recognized later, and studies have revealed its crucial role in male and female fertility, as well as proper reproductive function during pregnancy. Vitamin D deficiency has been identified as a risk factor for infertility, gonadal cancers, pregnancy complications, polycystic ovary syndrome, and endometriosis. However, data investigating the association between vitamin D levels and reproductive disorders, including endometriosis, have encountered inconsistencies. Therefore, the present study aims to review existing research on the effect of vitamin D on proper reproductive function, and the role of deficiency in reproductive diseases and specifically focuses on endometriosis.

Keywords: Endometriosis; Reproductive disorders; Vitamin D; Vitamin D binding protein; Vitamin D deficiency.

Fig. 1

Vitamin D synthesis. Abbreviations: DBP: Vitamin D-binding protein; PTH: Parathyroid hormone

Fig. 2

Key signaling pathways involved in endometriosis progression and the effects of vitamin D on these pathways. Abbreviations: TGF-βR: Transforming growth factor beta receptor; IGF-1R: Insulin-like growth factor 1 receptor; EGFR: Epidermal growth factor receptor

Fig. 3

The causes and mechanisms underlying the development of endometriosis