Evidence check: VDR in the context of Fruchtbarkeit

The vitamin D receptor (VDR) mediates the genomic effects of vitamin D, which is known to influence fertility through roles in steroidogenesis, oocyte maturation, sperm quality, and implantation. Common VDR polymorphisms (e.g., FokI, BsmI, TaqI, ApaI) have been studied for associations with fertility outcomes, but the evidence remains largely mechanistic and observational. Effect sizes are small, and findings are inconsistent across populations. A consumer DNA test reporting VDR variants does not provide actionable fertility guidance on its own. The actual serum vitamin D level is a more clinically relevant marker, modifiable through sun exposure, diet, or supplementation. Caveat: Direct-to-consumer tests often overstate the significance of such genetic variants. Fertility issues should always be evaluated by a specialist, and no change in management should be based solely on a VDR genotype.