Harvard Health Letter

In search of vitamin D

The exact dosage of vitamin D required for bone health is controversial. Supplements of 400 international units (IU), along with 1,000 milligrams (mg) of calcium, won’t do much. Harvard experts recommend 1,000 IU of vitamin D per day (up to 2,000 IU in patients at risk for vitamin D deficiency), along with 1,000 to 1,200 mg of daily calcium in divided doses, ideally from both food sources and supplements. However, the right dosage for each person depends on his or her age, bone density, and vitamin D levels.  
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