Sunlight, Vitamin D & Prostate Cancer

This science-based book is the first to demonstrate that in prostate cancer, insufficient access to the sun's short wavelength ultraviolet-B irradiance, necessary for photosynthesis of vitamin D, increases the risk of progression. The author surveys five populations with steeply elevated mortality from prostate cancer: African-North Americans, Norwegians, Swedes, Swiss and Danes. He finds that insufficient exposure to UV-B and inadequate photosynthesis of vitamin D is common to them all. Based on data extracted from World Health Statistics Annuals published in hard copy by the World Health Organization (WHO) in the 1980s, graphs depicting age-specific rates of prostate cancer mortality in Western European countries show that the Swiss rates are anomalously high for the country's latitude and may even surpass the rates for Norway and Sweden. Age-standardized (world) statistics published on-line by the WHO's International Agency for Research into Cancer (IARC) in its Globocan 2000 Cancer Epidemiology Database list identical rates for Norway, Sweden and Switzerland. The age-specific and age-standardized rates of prostate cancer mortality reported for other northern alpine countries are normal for the latitudes. Their more extensive surface areas and dispersed populations, with the great majority of their citizens residing far from the Alps, are consistent with this. In a population survey conducted by Swiss scientists from two institutions, blood levels of calcidiol (25-hydroxyvitamin D), the body's major circulating reservoir of the vitamin, were measured in a large representative sample of adults in all age groups. Subjects older than 65 were found to be spending less than 30 minutes a day outdoors in the summer. This is significant, because the capacity of exposed skin to photosynthesize vitamin D declines with age. Moreover, its inverse correlation with the intensiveness of pigmentation means that African-North Americans in particular need to spend longer periods of time in direct sunlight than may be possible for a variety of reasons. The book contends that many aging individuals residing far from the Equator can achieve year-round sufficiency in vitamin D through relatively frequent, brief periods of exposure to sunlight, reinforced in winter by adequate supplementation. Published research indicating how many international units of the vitamin may be needed daily is also discussed. There is a detailed description of the mechanism whereby minute quantities of a powerful steroid hormone (calcitriol) metabolized from calcidiol, bind to the hormone's receptors (VDR) within the nuclei of the cells. By a signalling procedure involving "cross talk" between the hormone and the VDR, and resulting changes in the transcription of genes within the nuclei, proliferation of malignant cells can be inhibited. Besides prostate cancer, several other common cancers are reported to be associated with deficiencies of vitamin D. "Recommended reading for anyone interested in lowering their risk of prostate cancer"---Christopher Morash, MD, FRCSC, Chief of Urosurgical Oncology, Ottawa Regional Cancer Centre, Ottawa, Ontario. Read more