This Article Full Text Full Text (PDF) All Versions of this Article: 92/6/2130    most recent Author Manuscript (PDF) Submit a related Letter to the Editor View responses Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Binkley, N. Articles by Drezner, M. K. Search for Related Content PubMed PubMed Citation Articles by Binkley, N. Articles by Drezner, M. K. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Medline Plus Health Information Nutrition Related Collections Calcium and Bone Metabolism

Low Vitamin D Status despite Abundant Sun Exposure

University of Wisconsin Osteoporosis Clinical Research Program (N.B., D.K., T.K., M.K.D.), Madison, Wisconsin 53705; Human Nutrition, Food and Animal Sciences (R.N., Y.G.D.), University of Hawaii at Manoa, Honolulu, Hawaii 96822; Laboratory Medicine (G.L.), University of Wisconsin, Madison, Wisconsin 53792; and Medical University of South Carolina (B.W.H.), Charleston, South Carolina 29425

Address all correspondence and requests for reprints to: Neil Binkley, M.D., University of Wisconsin Osteoporosis Research Program, Suite 100, 2870 University Avenue, Madison, Wisconsin 53705. E-mail: nbinkley{at}wisc.edu.

Context: Lack of sun exposure is widely accepted as the primary cause of epidemic low vitamin D status worldwide. However, some individuals with seemingly adequate UV exposure have been reported to have low serum 25-hydroxyvitamin D [25(OH)D] concentration, results that might have been confounded by imprecision of the assays used.

Objective: The aim was to document the 25(OH)D status of healthy individuals with habitually high sun exposure.

Setting: This study was conducted in a convenience sample of adults in Honolulu, Hawaii (latitude 21°).

Participants: The study population consisted of 93 adults (30 women and 63 men) with a mean (SEM) age and body mass index of 24.0 yr (0.7) and 23.6 kg/m² (0.4), respectively. Their self-reported sun exposure was 28.9 (1.5) h/wk, yielding a calculated sun exposure index of 11.1 (0.7).

Main Outcome Measures: Serum 25(OH)D concentration was measured using a precise HPLC assay. Low vitamin D status was defined as a circulating 25(OH)D concentration less than 30 ng/ml.

Results: Mean serum 25(OH)D concentration was 31.6 ng/ml. Using a cutpoint of 30 ng/ml, 51% of this population had low vitamin D status. The highest 25(OH)D concentration was 62 ng/ml.

Conclusions: These data suggest that variable responsiveness to UVB radiation is evident among individuals, causing some to have low vitamin D status despite abundant sun exposure. In addition, because the maximal 25(OH)D concentration produced by natural UV exposure appears to be approximately 60 ng/ml, it seems prudent to use this value as an upper limit when prescribing vitamin D supplementation.

This article has been cited by other articles:

				J. C. Fleet, C. Gliniak, Z. Zhang, Y. Xue, K. B. Smith, R. McCreedy, and S. A. Adedokun Serum Metabolite Profiles and Target Tissue Gene Expression Define the Effect of Cholecalciferol Intake on Calcium Metabolism in Rats and Mice J. Nutr., June 1, 2008; 138(6): 1114 - 1120. [Abstract] [Full Text] [PDF]

				N. Binkley, D. Krueger, D. Gemar, and M. K. Drezner Correlation among 25-Hydroxy-Vitamin D Assays J. Clin. Endocrinol. Metab., May 1, 2008; 93(5): 1804 - 1808. [Abstract] [Full Text] [PDF]

				S T Weiss and A A Litonjua Author's reply Thorax, March 1, 2008; 63(3): 293 - 293. [Full Text] [PDF]

eLetters: