UV radiation and vitamin D

The importance of vitamin D’s absorption through sunlight

According to scientific insights, the human species most likely originated in Africa where humans were exposed to many hours of sunlight on a daily basis; therefore, our organism is capable of coping with long periods of exposure to sunlight. More than that, we are accustomed to sunlight and require it as a foundational pillar of life. The human body has learned to produce vitamin D through the skin by absorbing UV rays and has integrated this process into our system as the main supplier of essential vitamin D. Vitamin D consumption through food represents only a small portion of our total vitamin D intake. It has, meanwhile, become well known that a sufficient supply of vitamin D is absolutely vital, not only for our bones, but also for our nerves, skin, hair,our psyche and many other areas within our organism, which profit from an optimal supply of sun vitamins. Vitamin D is not only highly important for more than 200 metabolic processes, it is also one of the most important substances for cancer prevention. As humans, we generate between 10,000–20,000 international units (I.U.) daily when exposed to solar radiation. The 600-1,000 I.U. prescribed by doctors as tablets or capsules seem rather pitiful in light of this.



In our latitudes, vitamin D production through the skin is only possible to a limited extent. The production via the skin depends on the intensity of solar radiation and the angle of incidence.

In the winter half-year from October to the end of March, the human skin produces no vitamin D in European and North American latitudes, and in the summer half-year, production only takes place when we are in bathing suits or bikinis and our skin is directly exposed to the sunlight.

No vitamin D is produced through the skin if the sun does not contact it, as is the case for the greater part of the population who work indoors or in offices. Exposure is so limited that I have detected vitamin D deficiency in approx. 90% of my patients.

Hardly anyone walks into my practice with a so-called 25-OH-D value within the optimal range of 60-70 nmol/L.


Excerpt from the book “Uwe Karstädt: 98.6° F – Ideal Body Temperature

Copyright 2014 | uwekarstaedt.de


About Uwe Karstaedt

The German naturopath lives and works in Munich since 1986 and has published many bestselling books on health and alternative medicine. He is an inspiring speaker with a fascinatingly broad range of in depth knowledge about the basic principles of healing on all levels.

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