Vitamin D supplementation during Antarctic winter

• Published in: The American journal of clinical nutrition Vol. 89; no. 4; pp. 1092 - 1098
• Main Authors: Smith, Scott M, Gardner, Keri K, Locke, James, Zwart, Sara R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutrition 01.04.2009; American Society for Clinical Nutrition, Inc
• Subjects: 25-hydroxycholecalciferol; Adult; adults; Antarctic Regions; Antarctica; Biological and medical sciences; Bone Density Conservation Agents - administration & dosage; Bone Density Conservation Agents - biosynthesis; Clinical trials; Diet; Dietary Supplements; Dose-Response Relationship, Drug; Double-Blind Method; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; nutrition assessment; nutritional status; Prospective Studies; Seasons; solar radiation; space flight; Studies; Sunlight; Ultraviolet radiation; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin D; Vitamin D - administration & dosage; Vitamin D - analogs & derivatives; Vitamin D - biosynthesis; Vitamin D - blood; Vitamin D Deficiency - blood; Vitamin D Deficiency - prevention & control; vitamin supplements; Winter; Antarctica; Human; Supplementation; Winter; Vitamin D
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.3945/ajcn.2008.27189

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 > or = 80 nmol/L. 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. 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. 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. 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.