Vitamin D is vital for calcium absorption in bones and to improve muscle strength. Not getting enough vitamin D in childhood can slow growth or cause misshapen bones (rickets); not getting enough vitamin D throughout life increases the risk for bone thinning (osteoporosis) in later years.

Most doctors suggest daily vitamin D supplements of 200 to 400 IU for children and teens, starting by age 2 months.

A person age 19 to 50 needs 400 to 800 IU of vitamin D every day. A person age 50 and older needs 800 to 1,000 IU of vitamin D every day. People who live in sunny climates can get enough vitamin D through 10 to 15 minutes per day of sun exposure a few days a week.

You can get the amount of vitamin D you need each day by eating a variety of dairy products. Vitamin D is in foods such as egg yolks, liver, saltwater fish, and vitamin D-fortified dairy products. Vitamin D also is available in supplements, often in combination with calcium.