Vitamin D Interpreter.
Enter your 25-OH vitamin D level to see whether you are deficient, optimal, or pushing into excess — with the IOM and Endocrine Society thresholds side by side.
Deficient, optimal, or too much?
A 25-hydroxyvitamin D blood test is the standard measure of vitamin D status. The thresholds are genuinely contested: the Institute of Medicine set 20 ng/mL as the population floor for bone health, while the Endocrine Society argues for 30+ ng/mL as optimal. Most practitioners converge on a 30–50 ng/mL target — enough for bone, immune, and muscle function without chasing levels that carry no proven added benefit.
More is not better. Above roughly 100 ng/mL, vitamin D toxicity (driven by high calcium) becomes a real risk, and it comes almost entirely from over-supplementing rather than sun or food. Because the vitamin is fat-soluble, absorb supplements with a meal; adequate magnesium is needed to activate it, and vitamin K2 helps steer the resulting calcium into bone rather than arteries.
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. (2011). Evaluation, treatment, and prevention of vitamin D deficiency: Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 96(7), 1911–1930.
- Institute of Medicine. (2011). Dietary Reference Intakes for Calcium and Vitamin D. National Academies Press.
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