A study that correlated exposure to sunlight with cancer risk found that people exposed to more sunlight had a significantly lower risk of many types of cancer (Lin, 2012). This study followed more than 450,000 white, non-Hispanic subjects aged 50-71 years from diverse geographic areas in the US. Researchers correlated the calculated ultraviolet radiation (UVR) exposure in these different areas with the incidence of a variety of cancers. The diverse sites included six states (California, Florida, Louisiana, New Jersey, Pennsylvania, and North Carolina), and the metropolitan areas of Atlanta and Detroit. They followed these subjects over a period of nine years in the study and eliminated other known risk factors for cancer such as smoking, body mass index, and physical activity. This was the first prospective study (participants were actively observed for the duration of the study) to look at the relationship of sunlight to cancer.
A total of 75,000 participants In the study contracted cancer. The study found that 12 types of cancer were reduced in those subjects exposed to more sunlight. These included cancers of the lungs, prostate, pancreas, colon, thyroid and many other types. As expected melanoma and other skin cancers occurred more often in the participants exposed to more sunlight. The incidence of cancers of female organs including the ovaries, breast, and uterus were not reduced in this study, possibly because men spend more time outdoors than women. This confirmed a previous study that showed a decreased incidence of cancer in men but not women in relation to sun exposure (Grant, 2012).
This research confirms the protective effect of Vitamin D for many types of cancer. No other known factors in sun exposure would account for these findings. This provides more evidence that sun exposure is protective and that the routine use of sunscreens is counterproductive. Sunscreen should be used to prevent sunburn during prolonged exposure to bright sun at midday. Otherwise sun exposure and ultraviolet radiation promote health. Similarly, in parts of the world and times of the year with limited sun exposure taking a vitamin D supplement in adequate amounts is beneficial to the immune system, promotes bone growth, prevents cardiovascular disease, and reduces the incidence of cancer.