Vitamin D Deficiency in Europeans Today and in Viking Settlers of Greenland.

The vast majority of the Earth's population lives between the 20th and 40th parallel north and south. It seems that right here humans have found the best living conditions relating not only to temperature and food recourses, but also to UV radiation necessary for the production of vitamin D by human skin. An exception to this general rule is Europe. Nearly half a billion people live between the 40th and 60th parallel north of the equator despite the fact that the amounts of UV radiation there are much lower. Moreover, since the time of the Vikings, there has always been a part of the European population that lived even further north than the 60th parallel (the northern parts of Europe, including Greenland). In this work, we present the potential role that vitamin D deficiency might have played in the extinction of the Vikings of Greenland. We analyze factors that contribute to the discrepancy between the theoretical distribution of areas with vitamin D deficiency and today's reality, like the impact of civilization, religious traditions, as well as vitamin D supplementation in food products and as a biologically active dietary additive. The global migration of people on a scale and speed never seen before is now even more important for this discrepancy.

Vitamin D -- the sun hormone. Life in environmental mismatch.

While some representatives of the animal kingdom were improving their biological mechanisms and properties for adapting to ever-changing life conditions, the genus Homo was developing backward: human individuals were losing their adaptation to life areas conquered earlier. Losing step-by-step their useful traits including the body hair cover, the primitive genus Homo retained his viability only under very favorable conditions of the equatorial Africa. Protection from UV radiation danger was provided only by pigmentation of skin, hair, and eyes. However, "impoverished" individuals of this genus gained the ability to walk upright. Their hands became free from participation in movement and became fine tools for producing useful instruments, from the stone knife to the computer. The major consequence of upright movement and hand development became the powerful development of the brain. A modern human, Homo sapiens, appeared capable of conquering very diverse new habitats. The human's expansion on the Earth occurred somewhat limited by his dependence on vitamin D. His expansion into new areas with lower Sun activity was partially associated with the loss of skin pigmentation. But there is an open question, whether under these new conditions he is satisfactorily provided with vitamin D. This paper discusses the following problems: how can we ensure a sufficient intake of vitamin D, how much does an individual require for his existence and optimal life, what will be consequences of vitamin D deficiency, and what are the prospects for better provision with vitamin D?