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...

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...

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: 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...

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...

OBJECTIVES Seasonal variations in ultraviolet B (UVB) radiation cause seasonal variations in vitamin D status. This may influence immune responses and play a role in the seasonality of influenza. METHODS Pandemic and non-pandemic influenzas in Sweden, Norway, the USA, Singapore, and Japan were studied. Weekly/monthly influenza incidence and death rates were evaluated in view of monthly UVB fl...

Solar ultraviolet (UV) radiation is one of the most important factors in the development of skin cancer in human, solar erythema and skin aging. Nevertheless, numerous studies have shown the benefits of UV solar radiation in moderate doses, such as the reduction of blood pressure and mental health, treatment of various diseases, and the synthesis of vitamin D in the skin. This paper analyses da...

Deficiency of sunshine vitamin ‘Vitamin D’ and diabetes mellitus are two common conditions encountered during clinical practice and they are widely prevalent across all ages, races, geographical regions and socioeconomic conditions [1]. More than one billion people worldwide are likely to have vitamin D deficiency due to a lack of sunshine exposure. Vitamin D (Calciferol) which comprises a grou...