You need vitamin D to absorb calcium and reduce inflammation, as well as for the mineralization of your bones and proper immune function and cell growth. Fatty fish, cheese and egg yolks contain some vitamin D, but most of the vitamin D you get from food comes from fortified foods, such as milk and some types of orange juice. However, spending time in the sun can increase your vitamin D levels as well.
Sunlight and Vitamin D
Although you don't need to spend time in the sun for your body to use vitamin D, spending time in the sun under the right conditions makes it possible for your body to make vitamin D. Sunscreen blocks the UV rays your body needs, and at certain times of the year, the sun may not get high enough in the sky for the rays to penetrate the atmosphere if you live too far north or south of the equator. If you have light skin, it only takes a few minutes in the sun a day to meet your vitamin D requirements, but if you have darker skin it takes longer to meet your vitamin D requirements. Older adults cannot make vitamin D as efficiently with sun exposure, however.
Vitamin D Requirements
The recommended dietary intake of vitamin D for everyone between the ages of 1 and 50 is 600 IU per day. Older adults need 800 IU per day, and infants up to 12 months old need 400 IU per day. Although consuming too little vitamin D can cause deficiency symptoms, it is also possible to consume too much vitamin D. Those ages 9 and older should not consume more than the tolerable upper intake limit of 4,000 IU per day unless under the supervision of a doctor.
Deficiency
Older adults, breastfed babies, people with dark skin, people who don't get much exposure to the sun, people who have undergone gastric bypass surgery and people with fat absorption problems are at higher risk for vitamin D deficiency and may need supplemental vitamin D. Deficiency symptoms include soft bones, bone pain and muscle weakness. Being deficient in vitamin D may also increase your risk for health problems, including heart attacks, according to a June 2008 article in U.S. News & World Report Health.
Considerations
You don't want to spend too much time in the sun without sunscreen, as this can increase your risk for skin cancer. Between 5 minutes and 30 minutes of unprotected sun exposure is enough for most people, notes the U.S. News & World Report Health article. You can also increase your vitamin D levels by consuming more foods containing vitamin D or taking vitamin D supplements or multivitamins containing vitamin D.
References
- Office of Dietary Supplements: Vitamin D
- "U.S. News & World Report"; Time in the Sun: How Much Is Needed for Vitamin D?; Deborah Kotz; June 2008
- "American Journal of Clinical Nutrition"; Sunlight and Vitamin D for Bone Health and Prevention of Autoimmune Diseases, Cancers, and Cardiovascular Disease; Michael F. Holick; December 2004
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