Covering up the body against sunlight in general and UVB radiation in particular is generally considered as being protective against skin cancer. However, recently a group of scientists led by Wanqing Chen showed that mortality rates from major cancers in Chinese people are, like in the West, inversely correlated with ambient UVB radiation. This is also true for the incidence of some cancer types, such as oesophagus, stomach, colon, rectum and cervix.
According to the outcome of their survey, the researchers suggest that the sunshine vitamin, created naturally in the body by exposure to ultra violet, may reduce the incidence or improve the course of cancer in Chinese people. The study shows that industrialisation and a lack of sun exposure go hand in hand.
The researchers analysed cancer mortality data in a sample of 263 counties in China from 1990 to 1992, as well as national cancer registration data from 1998 to 2002, to estimate cancer incidence. Satellite measurements of cloud-adjusted ambient UVB intensity were used to estimate the average daily irradiance for the 263 counties in 1990.
“Under the influence of UVB radiation over 90 percent of vitamin D needed by the body is formed in the skin”, Ad Brand from the Sunlight Research Forum (SRF) explains, “Because of the scientifically verified positive effect of high vitamin D levels (40 to 60 nanograms per millilitre of blood are optimal) the SRF recommends a regular, but moderate exposure to UVB irradiance – either in the sun or under a solarium”.
Source: The Sunlight Research Forum