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This Article Full Text (Publish Ahead of Print[PDF]) All Versions of this Article: 89/4/1092    most recent ajcn.2008.27189v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Smith, S. M Articles by Zwart, S. R Search for Related Content PubMed PubMed Citation Articles by Smith, S. M Articles by Zwart, S. R Agricola Articles by Smith, S. M Articles by Zwart, S. R

Vitamin D supplementation during Antarctic winter^1,2,3

¹ From the Space Life Sciences Directorate, National Aeronautics and Space Administration Johnson Space Center, Houston, TX (SMS and JL); the UCLA School of Medicine and VA Greater Los Angeles Health Care System, Los Angeles, CA (KKG); and the Universities Space Research Association, Houston, TX (SRZ).

² Supported by the NASA Human Research Program and made possible by the National Science Foundation.

³ Address reprint requests and correspondence to SM Smith, NASA Johnson Space Center, Mail Code SK3, 2101 NASA Parkway, Houston, TX 77058. E-mail: scott.m.smith{at}nasa.gov.

ABSTRACT

Background: Persons with limited exposure to ultraviolet B light, including space travelers, may not receive enough vitamin D. Recent studies indicate that optimal serum 25-hydroxyvitamin D [25(OH)D] should be 80 nmol/L.

Objective: This study was designed to evaluate the effectiveness of 3 doses of vitamin D to raise and maintain 25(OH)D to a concentration >80 nmol/L in persons with limited ultraviolet B light exposure.

Design: This was a 5-mo prospective, randomized, double-blind study of vitamin D supplementation. It was conducted during winter in Antarctica at the McMurdo Station, when ultraviolet B radiation levels are essentially zero. The 55 subjects were randomly divided into 3 groups for vitamin D supplementation: 2000 IU/d (n = 18), 1000 IU/d (n = 19), and 400 IU/d (n = 18). An additional 7 subjects did not take supplements or took supplements of their own choosing. Blood samples were collected about every 2 mo during the winter.

Results: About 5 mo after supplementation started, 25(OH)D increased to 71 ± 23 nmol/L in the 2000-IU/d group, 63 ± 25 nmol/L in the 1000-IU/d group, and 57 ± 15 nmol/L in the 400-IU/d group and decreased to 34 ± 12 nmol/L in the group not taking supplements.

Conclusions: These data will enable us to provide space crews with evidence-based recommendations for vitamin D supplementation. The findings also have implications for other persons with limited ultraviolet light exposure, including polar workers and the elderly.

Received for publication November 4, 2008. Accepted for publication January 18, 2009.