Evidence check: VDR in the context of longevity

A vitamin D level of 18 ng/mL indicates insufficiency (optimal: 30–50 ng/mL). Supplementation is often warranted, but stay below 4,000 IU/day without medical supervision. Vitamin D acts through the VDR (vitamin D receptor). Genetic variants in the VDR gene (e.g., rs2228570, rs1544410) can modestly affect receptor function, but they rarely explain such a low level. The main causes are usually inadequate sun exposure or diet. In the context of longevity, observational studies link adequate vitamin D status to lower all-cause mortality, but the evidence is not causal. DNA tests can detect VDR variants, but they cannot replace blood testing. Supplement decisions should be guided by blood levels, not genetics. Caveat: marketing often overstates the impact of single VDR SNPs on lifespan.