By Marc Sorenson, EdD, Sunlight Institute…
Case-control research from Iran indicates that lack of sun exposure is a major risk factor for breast cancer. Two groups of women, one that had breast cancer (cases) and another that was normal (controls), were assessed by questionnaire regarding lifestyle choices and the risk for breast cancer. When assessing sun exposure habits, those who had the lowest level of sun exposure had nearly three times the risk of being a cancer victim as those who had the highest level.
This is the second Iranian study I am aware of that showed a remarkable difference in breast-cancer risk based on sun exposure. Another case-control study showed that women who covered themselves completely had more than 10 times the risk breast cancer compared to those who were not totally covered. Of transcendent importance was the unexpected finding that vitamin D levels were nearly identical in cases as controls, meaning that the protective mechanism could not have been vitamin D. Some other factor must have protected them from the disease. We have mentioned on this blog many times that sun exposure leads to higher levels of serotonin, endorphin, nitric oxide and other potentially helpful products.
Whatever the mechanism, it seem wise to get plenty of non-burning sunlight.
 Salarabadi A, Bidgoli SA, Madani SH. Roles of Kermanshahi Oil, Animal Fat, Dietary and Non- Dietary Vitamin D and other Nutrients in Increased Risk of Premenopausal Breast Cancer: A Case Control Study in Kermanshah, Iran. Asian Pac J Cancer Prev. 2015;16(17):7473-8.
 Bidgoli SA, Azarshab H. Role of vitamin D deficiency and lack of sun exposure in the incidence of premenopausal breast cancer: a case control study in Sabzevar, Iran. Asian Pac J Cancer Prev. 2014;15(8):3391-6.