Vitamin D intake is recommended at 400–800 IU/day, or 10–20 micrograms. Normal vitamin D levels in the blood are 20 ng/ml or above for adults.

Vitamin D is necessary for building and maintaining healthy bones. The Vitamin D Council recommends that healthy adults take 2,000 IU of vitamin D daily -- more if they get little or no sun exposure. That's because calcium, the primary component of bone, can only be absorbed by your body when vitamin D is present. People aged 1–70 years should aim to get at least 15 mcg or 600 IU of vitamin D per day…