Requirements for Vitamin D Across the Life Span

Adequate provision of vitamin D has been found, in ecological, cross-sectional, and observational studies, to be associated with reduction in the risk of many types of cancer, cardiovascular diseases (CVDs), autoimmune diseases, diabetes mellitus types 1 and 2, neurological disorders, several bacterial and viral infections, and adverse pregnancy outcomes in addition to the classical bone disorders of rickets and osteomalacia. Furthermore, investigators have found adequate repletion and increased intakes of vitamin D to be associated with reduced all-cause mortality rates. These findings have been supported by the limited number of properly conducted randomized controlled trials (RCTs) that used more than 400 IU/day of vitamin D. This review presents an overview of the role of vitamin D for the promotion of health for the more important vitamin D-related diseases and conditions. Serum 25-hydroxyvitamin D concentrations of 30-60 ng/ml, corresponding to oral intake or skin production of 1,000-4,000 IU/day of vitamin D, appear necessary in adults for avoidance of hypovitaminosis D-related ill health. People of all ages are encouraged to obtain more vitamin D from judicious exposure to sunshine (for ultraviolet B [UVB] irradiation) or from regular vitamin D supplements because dietary sources do not provide sufficient vitamin D to prevent any health risks other than those of rickets and osteomalacia.