In their study, the research group determined the effect of an increased vitamin D intake on the mortality risk, based on the existing research findings and using the example of the five North European countries mentioned. An average vitamin D level of at least 70 nano molecules per millilitre of blood (70 nmol/L) is scientifically considered to be the value at which the positive effects of vitamin D are seen. Vitamin D production is stimulated by UV radiation with 90 percent of it being produced in the skin.
Note:
A summary of the study, “William B. Grant, Asta Juzeniene, Johan E. Moan: Health benefit of increased serum 25(OH)D levels from oral intake and ultraviolet-B irradiance in the Nordic countries; Scandinavian Journal of Public Health, 2011; 39: 70–78” can be found on the SRF-Website www.sunlightresearchforum.eu and is available to download.