As mentioned previously, the amount of vitamin D you need per day to maintain a normal level of 25OHD depends upon your skin color, sun exposure, diet, and underlying medical conditions.

In general, adults are advised to take a supplement containing 800 international units of vitamin D per day to maintain a normal vitamin D level. Older people who are confined indoors may have vitamin D deficiency even at this intake level.

All infants and children are advised to take a vitamin D supplement containing 400 international units of vitamin D, starting within days of birth. For infants and children, vitamin D is included in most non-prescription infant multivitamin drops. In some countries, it is possible to buy infant drops that contain only vitamin D.

Exposure to the sun or tanning beds is not recommended as a source of vitamin D because of the risk of skin cancer.