Journal of Steroid Biochemistry & Molecular Biology 97 (2005) 7–12 Dietary recommendations to meet both endocrine and autocrine needs of Vitamin D  Susan J. Whiting a,∗ , Mona S. Calvo b,1 a College of Pharmacy and Nutrition, 110 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5C9 b Center for Food Safety and Applied Nutrition (CFSAN), Food and Drug Administration MOD-1 Building, HFS-025, 8301 Muirkirk Road, Laurel, MD 20910, USA Abstract 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 12.5 g (500 IU) 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. © 2005 Elsevier Ltd. All rights reserved. Keywords: Vitamin D; Vitamin D intakes; Dietary reference intakes; Vitamin D fortification; Supplementation; Functional indicators 1. Introduction In the presence of adequate sunlight providing ultravi- olet light (UVB) in the wavelength range of 290–315 nm, a dietary intake of Vitamin D is not required. Under this condition, sufficient Vitamin D is made dermally from pre- vitamin D 3 a precursor molecule derived from cholesterol. This Vitamin D 3 is rapidly converted to 25 hydroxyvitamin  Disclaimer: The opinions and conclusions expressed in this article are solely the views of the authors and do not necessarily reflect those of the Foods and Drug Administration. ∗ Corresponding author. Tel.: +1 306 966 5837; fax: +1 306 966 6377. E-mail addresses: susan.whiting@usask.ca (S.J. Whiting), mona.calvo@cfsan.fda.gov (M.S. Calvo). 1 Tel.: +1 301 827 8492; fax: +1 301 594 5017. D 3 [25(OH)D] which is available for synthesis of 1,25 dihy- droxyvitamin D 3 , the active form of Vitamin D. However, when sun exposure is limited, as in winter months or deliber- ate lack of sun exposure, food sources such as oily fishes and fortified foods maintain serum levels of 25(OH)D. Vitamin D status is evaluated by measuring the circulating levels of 25(OH)D resulting from the combined contributions of diet and cutaneous synthesis. These dual sources of Vitamin D from both sunlight and food have made it difficult to estimate a dietary requirement for Vitamin D. Thus, in the most recent revision of the dietary recommendations for Americans and Canadians, the dietary reference intakes (DRI) [1], a rec- ommended dietary allowance (RDA) could not be set in the absence of an estimated average daily intake requirement. In this paper we describe how, with the availability of new data 0960-0760/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsbmb.2005.06.022