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.
Zeeb
Hajo
H
Bremer Institut für Präventionsforschung und Sozialmedizin (BIPS), Universität Bremen, Linzer Strasse 10, 28359 Bremen, Germany. zeeb@bips.uni-bremen.de
Greinert
Rüdiger
R
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