How much vitamin D do you need per day?

The recommended daily amount of vitamin D needed per day for adults and children is 600 international units. For those 71 years and older, the recommended dosage is 800 international units per day, according to WebMD.

The body needs vitamin D to absorb calcium, which keeps bones and muscles strong. A lack of vitamin D and calcium in children can cause rickets, a rare disease that causes weak bones. Most people, however, get enough vitamin D since many foods are fortified with both calcium and vitamin D. Additionally, the body uses sunshine to make its own vitamin D, notes WebMD.