In some countries, vitamin D is listed in micrograms, and the relationship is as follows: 2.5 mcg (micrograms) = 100 IU. 5 mcg = 200 IU. 10 mcg = 400 IU. 15 mcg = 600 IU. 20 mcg = 800 IU.

In the United States, current guidelines suggest that consuming 400–800 International Units (IU), or 10–20 micrograms (mcg), of vitamin D should meet the needs of 97%–98% of all healthy people.

Medically reviewed by Aviv Joshua, MS Vitamin D levels can be measured with a blood test. This test can indicate whether you have adequate levels, are at risk of a vitamin D deficiency, or have levels ...

A study published in the Journal of the Endocrine Society in November 2024 followed 221 older people with hypertension and had them take either 600 or 3,750 international units (IU) of vitamin D ...