Vitamin D: evidence and controversies: comment on the article by Gilaberte et al

Abstract

Vitamin D deficiency is associated with increased risk of approximately 100 conditions and diseases. Ecological, observational, and cross-sectional studies as well as randomized controlled trials support these associations. Observational studies, with support from the other types, provide the data needed to determine how serum 25-hydroxyvitamin D [25(OH)D] concentration affects disease incidence and mortality rates. The findings for breast and colorectal cancer, respiratory infections, and all-cause mortality rates indicate that benefits increase as serum 25(OH)D concentrations increase to between 75 and 100nmol/L. Reaching those levels takes up to 5000IU of vitamin D per day, with considerable individual variation. The main sources of vitamin D that can help people reach those levels are UV-B irradiance and vitamin D(3) supplements. The skin characteristics-both in terms of pigmentation and ability to tan-of most inhabitants of Spain are ideally suited for regular moderate solar UV irradiance. In general, melanoma risk is low in southern Europe. Risk of nonmelanoma skin cancer is higher, but such cancers are seldom fatal, and a study in Denmark found a 9% reduction in 10-year all-cause mortality rate for patients diagnosed with basal cell carcinoma.