How much vitamin D do I need, and does everyone need a blood test?
Nutritional requirements are not treatment doses. US reference intakes are 400 IU daily in infancy, 600 IU from age 1 to 70, and 800 IU after 70, from total intake. Deficiency treatment is individualised; routine testing is not recommended for every healthy person.
Details
When does the plan change?
Malabsorption, kidney conditions, medicines, age and pregnancy can affect assessment. Reference intake does not mean everyone needs that amount as a supplement, and it does not prescribe treatment for confirmed deficiency.
Is one blood target required?
The Endocrine Society’s 2024 prevention guideline does not establish one disease-prevention blood target for healthy people. When testing is indicated, interpretation depends on the clinical setting and laboratory units, rather than applying a threshold of 30 to everyone.
Avoid overlapping supplements
Check prenatal vitamins, calcium products and other supplements for duplicate vitamin D. Unmonitored high doses can raise calcium and damage kidneys. Do not self-prescribe weekly or monthly treatment doses.
Related reading: How can I choose a balanced and safe diet during pregnancy?.