Vitamin D has many roles in the body. This nutrient is needed for bone growth and maintenance. Strong evidence suggests that it promotes calcium absorption, modulates cell growth, supports neuromuscular and immune function and reduces inflammation.
Vitamin D deficiencies cause rickets in children and osteomalacia in adults. Recently, numerous and extensive studies have been conducted regarding vitamin D that suggest health benefits for many other serious and chronic health conditions.
Studies have also found that there are widespread deficiencies in vitamin D in populations across the globe. As a result, there have been several recent increases in the recommended daily intake of vitamin D. In 2008, the American Academy of Pediatrics updated guidelines for vitamin D daily intake for infants 0-1 year old and children and adolescents from 200 IU to 400 IU. In 2010, the Institute of Medicine set new recommended daily allowances for those 1-70 years of age at 600 IUs; for those 71 years and older, 800 IU daily; and for pregnant and lactating women, 600 IU daily.
Relatively few foods naturally contain vitamin D. It is best obtained from sunshine; however, the use of sunscreen can limit the amount of vitamin D absorbed by the sun. People living in cloudy or rainy climates are also often prone to vitamin D deficiency. Certain cod liver oils can also be a good source of vitamin D.
Vitamin D levels fluctuate in the body due to many factors. Laboratory tests can be done to establish a baseline level that physicians may use to suggest adequate dosing.