Dr Grant cites several reasons why so called ecological studies are better for studying the association between UV radiation, vitamin D, and the prevalence of cancer than other types of epidemiological studies. We do not share his view since ecological studies are very prone to biases. Even by controlling for other variables that may be available only at group level, such studies do not become much more meaningful. We mentioned the excellent method of boosting levels of vitamin D by means of brief UV exposure.
Professor Koch and Dr Ullah mention as yet unexplained associations between vitamin D deficiency and other chronic diseases and call for vitamin D substitution without specifying which groups of persons should be treated in this way. Our article was written from an epidemiological perspective and focused on the questions to what extent vitamin D has a proven carcinopreventive effect and whether the current state of knowledge justifies a change in the recommendations for UV protection and prevention of skin cancer. Our position is clear: on the basis of the latest knowledge, vitamin D seems to have preventive potential but for a few types of cancer, but further studies are needed. Moderate sunlight exposure—while adhering to basic UV protection measures—is usually adequate in order to reach appropriate concentrations of vitamin D. In cases of seasonally deficient UV exposure, individual optimum concentrations of vitamin D can be ensured by ingesting appropriate foods (or food supplements).
Prof. Dr. med. Hajo Zeeb, MSc
Bremer Institut für Präventionsforschung und Sozialmedizin (BIPS)
Abt. Prävention und Evaluation
Bremen Institute for Prevention Research and Social Medicine (BIPS)
Department of Prevention and Evaluation
28359 Bremen, Germany
Conflict of interest statement
The authors declare that no conflict of interest exists
|1.||Zeeb H, Greinert R. The role of vitamin D in cancer prevention: Does UV protection conflict with the need to raise low levels of vitamin D? Dtsch Arztebl Int 2010; 107(37): 638–43. VOLLTEXT|