Posts Tagged 'vitamin d'

Sun Exposure and Cancer Risk

Due to the rapidly increasing malignant melanoma incidence seen across the developed world, sun exposure is generally perceived as  having an overall negative effect on health.  It is still debated how much of the increased rates has been due to improved surveillance and early diagnosis.  Dietary and lifestyle factors may also have contributed.   In the opinion of Moan et al. (2008), although a significant proportion of cases are caused by exposure to solar radiation, from vitamin D synthesis there is a net positive health effect of sun exposure, even for total cancer mortality.   The increased malignant melanoma rates with decreasing latitude in Europe is thought to be explained by variations in skin pigmentation.

Variations across North America and Europe showing trends of increased mortality rates for various cancers with increased latitude have supported the hypothesis first made in 1980 by Garland and Garland that vitamin D status accounts for the inverse association between solar UVB radiation exposure and risk of colon cancer.  Garland et al. (2009), who mention that there are supportive results for oral intake of vitamin D as well as from sun exposure, provide the following worldwide perspective on vitamin D and cancer prevention.

In regions such as Northern Europe where sunlight during winter is insufficient for vitamin D synthesis, supplementation is necessary to maintain optimal blood concentrations.  Supplementation would appear particularly important for dark-skinned people and for African-Americans mortality rates for many of the cancers linked to vitamin D are significantly increased.  The small cost of a daily dose of vitamin  could be balanced against the burden from cancer attributable to suboptimal vitamin D levels and it must surely be justifiable in many parts of the world.