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Author Notes:

Address for correspondence and reprint requests: Marji McCullough, ScD, RD Strategic Director, Nutritional Epidemiology American Cancer Society Epidemiology Research Program, 6D-234 250 Williams St. Atlanta, GA 30303-1002 Phone: 404-929-6816 FAX: 404-327-6450 marji.mccullough@cancer.org.

The authors report no conflicts of interest.

Research Funding:

This work was supported in part by Public Health Service grants R01 CA104637 and R03 CA121873 from the National Cancer Institute, and a Georgia Cancer Coalition Distinguished Cancer Scholar award to RMB.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Nutrition & Dietetics
  • RISK

Vitamin D Status and Impact of Vitamin D-3 and/or Calcium Supplementation in a Randomized Pilot Study in the Southeastern United States


Journal Title:

Journal of the American College of Nutrition


Volume 28, Number 6


, Pages 678-686

Type of Work:

Article | Post-print: After Peer Review


Objective: Vitamin D supplementation may be required for certain subgroups in the United States in whom status and intake are inadequate, but the impact of various doses, and whether calcium administration jointly or independently influences vitamin D metabolite levels, is unclear. Methods: In a pilot chemoprevention trial of biomarkers of risk for colorectal adenoma, we measured the impact of vitamin D supplementation and/or calcium supplementation on plasma vitamin D metabolite concentrations. Ninety-two adult men and women living in the southeastern United States were randomized to 800 IU vitamin D3, 2000 mg elemental calcium, both, or placebo daily for 6 months. We examined vitamin D status at baseline and postintervention and compared the change in plasma 25-hydroxyvitamin D (25(OH)D) and 1,25(OH)2D levels by intervention group using general linear models. Results: Eighty-two percent of the study population had insufficient plasma 25(OH)D concentrations (<75 nmol/L) at baseline, with the lowest levels observed among African American participants. Vitamin D supplements, with or without calcium supplementation, raised plasma 25(OH)D concentrations, on average, by 25 to 26 nmol/L. Half of the study participants were classified as having sufficient 25(OH)D status after 6 months of 800 IU of vitamin D3 daily. Calcium alone did not influence 25(OH)D concentrations. Conclusion: In this southeastern U.S. population, half of the study participants receiving 800 IU vitamin D3 daily had blood 25(OH)D concentrations of ≤75 nmol/L after a 6-month intervention period, supporting higher vitamin D dose requirements estimated by some groups. More research is needed to identify the optimal vitamin D dose to improve 25(OH)D status in various at-risk populations.

Copyright information:

© 2009 American College of Nutrition.

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