Vitamin D-3 4000 IU 120 caps by Kirkman Labs

Vitamin D has many roles in the body. This nutrient is needed for bone growth and maintenance. Strong evidence suggests that it supports calcium absorption, modulates cell growth and supports neuromuscular and immune system function.

Scientists are discovering that inadequate vitamin D is a widespread problem. 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 IUs; and for pregnant and lactating women, 600 IUs.

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 from the sun. People living in cloudy or rainy climates are also often prone to low vitamin D levels. 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 supplementation.