The role of vitamin D in cancer prevention: does UV protection conflict with the need to raise low levels of vitamin D?
BACKGROUND
Vitamin D is essential for life. Part of the body's supply of vitamin D is ingested in food, but UV induced vitamin D synthesis in the body plays an even more important role. UV irradiation is a cause for the currently rising incidence of skin cancer in many countries; on the other hand, Vitamin D might be protective against some cancers. In this paper we summarize the current data on vitamin D and cancer and on the vitamin D status of populations in Europe and discuss whether current recommendations on UV protection require changes.


METHODS
In 2008, the International Agency for Research on Cancer (IARC) published a systematic review on vitamin D and cancer. We describe its main findings and review additional publications retrieved by a selective literature search on vitamin D, UV light, and skin cancer. In addition, we systematically review the current recommendations on vitamin D supplementation.


RESULTS
Higher vitamin D levels are associated with a lower risk of colon cancer. For breast cancer, the situation is less clear. In general, higher vitamin D levels are associated with lower overall mortality. Concerning optimal Vitamin D levels, serum values ≥ 50 nmol/L (ie.. ≥ 20 ng/mL) are frequently discussed, and a few authors favor markedly higher values. Brief UV exposures are usually adequate for endogenous vitamin D synthesis.


CONCLUSIONS
More research is needed into the possible protective effects of vitamin D against cancer. Brief, daily UV exposure stimulates vitamin D production and causes negligible skin damage. Raising the vitamin D level even further by extended solar UV exposure or irradiation in a solarium is inadvisable because of the risk of skin cancer. Oral vitamin D supplementation can be considered as an alternative, particularly for persons at high risk, such as the elderly and members of certain ethnic groups.
Bremer Institut für Präventionsforschung und Sozialmedizin (BIPS), Universität Bremen, Linzer Strasse 10, 28359 Bremen, Germany. zeeb@bips.uni-bremen.de
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Zeeb
Rüdiger
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Greinert
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D003431:Cross-Cultural Comparison; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000401:mortality / Q000517:prevention & control*; D009749:Nutrition Surveys; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic; D012016:Reference Values; D013471:Sunburn / Q000517:prevention & control*; D013473:Sunscreening Agents / Q000009:adverse effects*; D015996:Survival Rate; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000008:administration & dosage* / Q000097:blood; D014808:Vitamin D Deficiency / Q000139:chemically induced* / Q000188:drug therapy*; D055815:Young Adult
D013473:Sunscreening Agents; D014807:Vitamin D