title: Vitamin D and fertility: a systematic review.
abstract: BACKGROUND
  Vitamin D has been well-known for its function in maintaining calcium and phosphorus homeostasis and promoting bone mineralization. There is some evidence that in addition to sex steroid hormones, the classic regulators of human reproduction, vitamin D also modulates reproductive processes in women and men.
  
  
  OBJECTIVE
  The aim of this review was to assess the studies that evaluated the relationship between vitamin D and fertility in women and men as well as in animals.
  
  
  METHODS
  We performed a systematic literature search in Pubmed for relevant English language publications published until October 2011.
  
  
  CONCLUSIONS
  The vitamin D receptor (VDR) and vitamin D metabolizing enzymes are found in reproductive tissues of women and men. Vdr knockout mice have significant gonadal insufficiency, decreased sperm count and motility, and histological abnormalities of testis, ovary and uterus. Moreover, we present evidence that vitamin D is involved in female reproduction including IVF outcome (clinical pregnancy rates) and polycystic ovary syndrome (PCOS). In PCOS women, low 25-hydroxyvitamin D (25(OH)D) levels are associated with obesity, metabolic, and endocrine disturbances and vitamin D supplementation might improve menstrual frequency and metabolic disturbances in those women. Moreover, vitamin D might influence steroidogenesis of sex hormones (estradiol and progesterone) in healthy women and high 25(OH)D levels might be associated with endometriosis. In men, vitamin D is positively associated with semen quality and androgen status. Moreover, vitamin D treatment might increase testosterone levels. Testiculopathic men show low CYP21R expression, low 25(OH)D levels, and osteoporosis despite normal testosterone levels.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria. elisabeth.lerchbaum@medunigraz.at
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Lerchbaum
authors.forename: Barbara
authors.initials: B
authors.lastname: Obermayer-Pietsch
mesh_terms: D000818:Animals; D005260:Female; D005298:Fertility / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D011247:Pregnancy; D018167:Receptors, Calcitriol / Q000378:metabolism; D014807:Vitamin D / Q000097:blood* / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy*
chemical_list: D018167:Receptors, Calcitriol; D014807:Vitamin D