What vitamin D level should I be aiming for?

There is no single agreed vitamin D target, and the disagreement is worth understanding rather than hiding. Two respected bodies set different numbers because they were answering different questions. The dietary reference intakes ask what level covers the needs of the population for bone health. The 2011 Endocrine Society guideline asked what level to aim for in patients already at risk of deficiency. The 2024 Endocrine Society guideline then changed the framing again by asking whether testing helps healthy people at all.

The numbers each body uses

The NIH Office of Dietary Supplements sets out four bands for serum 25-hydroxyvitamin D: below 12 ng/mL is deficient, 12 to below 20 ng/mL is generally inadequate, 20 ng/mL or above is generally adequate for bone and overall health, and above 50 ng/mL is linked to potential adverse effects. Vitamin D toxicity with hypercalcaemia is usually seen above 150 ng/mL. The 2011 Endocrine Society guideline defined deficiency as below 20 ng/mL, insufficiency as 21 to 29 ng/mL and sufficiency as 30 to 100 ng/mL for people at risk.

Who should be tested

The 2011 Endocrine Society guideline states: "We recommend screening for vitamin D deficiency in individuals at risk for deficiency. We do not recommend population screening for vitamin D deficiency in individuals who are not at risk." The 2024 Endocrine Society guideline went further and recommended against routine 25-hydroxyvitamin D testing in generally healthy adults, including adults with obesity and dark skin, on the grounds that the levels producing outcome-specific benefits have not been established in trials. In 2021 the US Preventive Services Task Force issued an I statement, concluding that evidence is insufficient to assess the balance of benefits and harms of screening asymptomatic adults.

Who the 2024 guideline still recommends supplementing

The 2024 Endocrine Society guideline suggests empiric supplementation, without testing first, for four groups: children and adolescents aged 1 to 18, adults aged 75 and over, people who are pregnant, and adults with high-risk prediabetes. Testing remains appropriate for people with malabsorption, chronic kidney disease, osteoporosis, hyperparathyroidism, prior bariatric surgery, or unexplained low calcium or high alkaline phosphatase, because in those situations the result changes what is done next.

If your level is between 20 and 30 ng/mL and you have no bone disease, malabsorption or kidney disease, the honest answer is that the evidence does not support chasing a higher number. If you are supplementing, keep to a daily dose rather than large intermittent doses, and do not aim for a level above 50 ng/mL.