This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due...

Introduction: Solar radiation has a major role in design, utilization, development, and planning of solar energy. The most important source of natural ultraviolet radiation is the sun, which has an important role in many biologic processes. Some of these processes are useful, like the production of vitamin D in the body, or curing rickets, and some of them are not, such as ski...

Introduction: Normal exposure to sunlight results in the production of vitamin D in human body, which happens because of the interaction between ultraviolet radiation and cholesterol in skin. Exposure to sunlight is responsible for 90 percent of vitamin D needed for the body. Studies show that Iran is a country with high percentage of lack of vitamin D (83 percent). Based on pr...

There is historic evidence that influenza pandemics are associated with solar activity cycles (the Schwabe-cycle of about 11-years periodicity). The hypothesis is presented and developed that influenza pandemics are associated with solar control of vitamin D levels in humans which waxes and wanes in concert with solar cycle dependent ultraviolet radiation. It is proposed that this solar cycle d...

The adequacy of the UV Index (UVI), a simple measure of ambient solar ultraviolet (UV) radiation, has been questioned on the basis of recent scientific data on the importance of vitamin D for human health, the mutagenic capacity of radiation in the UVA wavelength, and limitations in the behavioral impact of the UVI as a public awareness tool. A working group convened by ICNIRP and WHO met to as...

Introduction: Solar energy is one of the free sources, clean and environmentally friendly energy. Sun is the most important source of natural ultraviolet radiation that has a major role in the life of living beings. Industrial and medical applications of ultraviolet radiation have been clearly proven, like the production of vitamin D or treatment of many diseases, and also har...

Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanni...

Exposure to ultraviolet B radiation in sunlight provides the mechanism for more than 90% of the vitamin D production in most individuals. Concern has been expressed in recent years that the widespread use of sunscreens, particularly those with high sun protection factors, may lead to a significant decrease in solar-induced previtamin D(3) in the skin, resulting in a vitamin D level which is con...

Recent studies suggest that vitamin D may be associated with reduced breast cancer risk, but most studies have evaluated only dietary vitamin D intake. The associations among ultraviolet radiation from sunlight, factors related to cutaneous vitamin D production, and breast cancer risk were evaluated in a population-based case-control study conducted in Ontario, Canada, between 2003 and 2004 (n ...