Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitudes - 24/04/13
See commentary on page 935
Abstract |
Background |
The relationship between oral vitamin D supplementation and cutaneous photosynthesis is not well understood.
Objective |
We sought to provide estimates of the equivalency of vitamin D production from natural sun exposure versus oral supplementation.
Methods |
Using the FastRT simulation tool, we determined sun exposure times needed to achieve serum vitamin D3 concentrations equivalent to 400 or 1000 IU vitamin D for individuals of various Fitzpatrick skin types living in Miami, FL, and Boston, MA, during the months of January, April, July, and October.
Results |
Peak ultraviolet B irradiation for vitamin D synthesis occurs around 12 pm Eastern Standard Time (EST). In Boston, MA, from April to October at 12 pm EST an individual with type III skin, with 25.5% of the body surface area exposed, would need to spend 3 to 8 minutes in the sun to synthesize 400 IU of vitamin D. It is difficult to synthesize vitamin D during the winter in Boston, MA. For all study months in Miami, FL, an individual with type III skin would need to spend 3 to 6 minutes at 12 pm EST to synthesize 400 IU. Vitamin D synthesis occurs faster in individuals with lighter Fitzpatrick skin types. The duration to attain 1000 IU of vitamin D is longer in all scenarios.
Limitations |
Results of the computer model are only approximations. In addition, calculations were made based on the assumption that ¼ of 1 minimal erythema dose directed at ¼ body surface area is equal to 1000 IU of oral vitamin D.
Conclusions |
Although it may be tempting to recommend intentional sun exposure based on our findings, it is difficult, if not impossible to titrate one’s exposure. There are well-known detrimental side effects of ultraviolet irradiation. Therefore, oral supplementation remains the safest way for increasing vitamin D status.
Le texte complet de cet article est disponible en PDF.Key words : oral supplementation, ultraviolet irradiation, vitamin D synthesis
Abbreviations used : BSA, EST, IARC, MED, SDD, UV
Plan
Funding sources: None. |
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Conflicts of interest: None declared. |
Vol 62 - N° 6
P. 929.e1-929.e9 - juin 2010 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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