Dietary recommendations to meet both endocrine and autocrine needs of Vitamin D.

In the most recent revision of the dietary recommendations for Americans and Canadians in 1997, a recommended intake for Vitamin D was set in the absence of an estimation of mean requirements. There are now new data to estimate average requirements; however, there must be consideration of factors affecting need in populations and of total body tissue needs including the prevention and treatment of cancer. A recent study provides dietary dose-response data in the absence of sun exposure, and a mean requirement of 12.5microg (500IU) was found for Caucasian men. A seasonal build up (summer) and waning (winter) of Vitamin D stores implies that the requirement of Vitamin D in complete absence of yearly summertime sun exposure would approach levels of intake that mimic Vitamin D gained from sun exposure. High prevalence of Vitamin D insufficiency and the re-emergence of rickets have been observed worldwide. For many countries without mandatory staple food fortification, Vitamin D intake is often too low to sustain healthy circulating levels of 25 hydroxyvitamin D. Even in some countries that require (mandatory) or allow fortification (optional), Vitamin D intakes are low in some groups due to their unique dietary patterns, such as low milk consumption, vegetarian diet, limited or no use of dietary supplements, or changes away from traditional food consumption. Supplement use can significantly increase Vitamin D intakes across all age and gender groups but the benefit is primarily gained in persons whose intakes are close to adequate. African American men and women have greater prevalence of Vitamin D insufficiency, which may be a factor in their susceptibility to certain cancers. New recommendations for Vitamin D should be made for the otherwise healthy populations in greatest need of dietary Vitamin D due to lack of adequate sun exposure.