The Linus Pauling Institute recommends that generally healthy adults take a minimum 2,000 IU (50 mcg) of supplemental vitamin D daily. Those in higher risk groups may require more. Most multivitamins contain only 400 IU of vitamin D, and vitamin D supplements with increased IU are recently available for additional supplementation.
Sun exposure, diet, skin color, and obesity have variable, substantial impacts on body vitamin D levels. To adjust for individual differences and ensure adequate body vitamin D status, the Linus Pauling Institute recommends aiming for a serum 25-hydroxyvitamin D level of at least 80 nmol/L (32 ng/mL).
Numerous observational studies have found that serum 25-hydroxyvitamin D levels of 80 nmol/L (32 ng/mL) and above are associated with reduced risk of bone fractures, several cancers, multiple sclerosis, and type 1 (insulin-dependent) diabetes. Infants, children, and adolescents should have a minimum daily intake of 400 IU (10 mcg) of vitamin D, a recommendation set by the American Academy of Pediatrics in 2008.