What role does Vitamin D 25-OH play in Fruchtbarkeit?

Vitamin D 25-OH (25-hydroxyvitamin D) is the circulating storage form that reflects overall vitamin D status and has a well-documented role in fertility. In women, vitamin D influences ovarian follicle development, endometrial receptivity, and implantation. Low 25-OH levels are associated with higher risks of polycystic ovary syndrome (PCOS), endometriosis, and lower success rates in assisted reproductive technologies. In men, vitamin D is involved in spermatogenesis, sperm motility, and testosterone production; deficiency correlates with reduced semen quality. Evidence comes mainly from observational studies and meta-analyses, while randomized controlled trials show mixed results. An optimal range (e.g., 30–50 ng/mL) is often recommended, but individual factors such as sun exposure, genetics (e.g., VDR polymorphisms), and underlying conditions must be considered. Supplementation should only be initiated after blood testing and medical advice, as excessive intake can be toxic. MyBody-X offers vitamin D testing but does not replace clinical diagnosis. Overall, vitamin D 25-OH is an important but not sole determinant of fertility.