While a large percentage of children have low blood vitamin D levels, the significance of these low levels and the impact on health is unclear. The purpose of this project is to determine the effects of varying doses of vitamin D supplementation over 12 weeks on blood indicators of health in white and black children, aged 9 to 13 years, from both the northern and southern US.
Vitamin D intakes in children do not meet current US Dietary Reference Intake recommendations and emerging evidence suggests that a significant number of children, particularly those with darker skin pigmentation, have inadequate levels of serum 25-hydroxyvitamin D \[25(OH)D\]. The optimum level of circulating 25(OH)D has not been clearly defined in children, nor is it known what functional outcome measures are ideal for defining this level, or if these requirements would differ by race. Graded doses of vitamin D3 supplementation will be used in this dual-site, 12-week trial. The investigators hypothesize that a dose-response relationship will be observed between vitamin D supplementation and intermediate endpoints of skeletal health, and that race will modify these responses.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Masking
QUADRUPLE
Enrollment
323
vitamin D3 supplementation at 400 IU vs 1,000 IU vs 2,000 IU vs 4,000 IU vs placebo for 12-weeks
The University of Georgia Dept of Foods & Nutrition
Athens, Georgia, United States
Indiana University School of Medicine
Indianapolis, Indiana, United States
Purdue University
West Lafayette, Indiana, United States
serum 25(OH)D
Time frame: 0 weeks
PTH
Time frame: 0 weeks
1,25(OH)2D
Time frame: 0 weeks
fractional calcium absorption
Time frame: 0 weeks
biochemical markers of bone turnover
Time frame: 0 weeks
serum 25(OH)D
Time frame: 3 weeks
serum 25(OH)D
Time frame: 6 weeks
serum 25(OH)D
Time frame: 9 weeks
serum 25(OH)D
Time frame: 12 weeks
PTH
Time frame: 3 weeks
PTH
Time frame: 6 weeks
PTH
Time frame: 9 weeks
PTH
Time frame: 12 weeks
1,25(OH)2D
Time frame: 3 weeks
1,25(OH)2D
Time frame: 6 weeks
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1,25(OH)2D
Time frame: 9 weeks
1,25(OH)2D
Time frame: 12 weeks
fractional calcium absorption
Time frame: 12 weeks
biochemical markers of bone turnover
Time frame: 3 weeks
biochemical markers of bone turnover
Time frame: 6 weeks
biochemical markers of bone turnover
Time frame: 9 weeks
biochemical markers of bone turnover
Time frame: 12 weeks
sunlight exposure
Time frame: 0 weeks
dietary data
Time frame: 0 weeks
physical activity data
Time frame: 0 weeks
serum and urinary calcium
Time frame: 0 weeks
body composition
Time frame: 0 weeks
sunlight exposure
Time frame: 3 weeks
sunlight exposure
Time frame: 6 weeks
sunlight exposure
Time frame: 9 weeks
sunlight exposure
Time frame: 12 weeks
dietary data
Time frame: 3 weeks
dietary data
Time frame: 6 weeks
dietary data
Time frame: 9 weeks
dietary data
Time frame: 12 weeks
physical activity data
Time frame: 3 weeks
physical activity data
Time frame: 6 weeks
physical activity data
Time frame: 9 weeks
physical activity data
Time frame: 12 weeks
serum and urinary calcium
Time frame: 3 weeks
serum and urinary calcium
Time frame: 6 weeks
serum and urinary calcium
Time frame: 9 weeks
serum and urinary calcium
Time frame: 12 weeks
body composition
Time frame: 3 weeks
body composition
Time frame: 6 weeks
body composition
Time frame: 9 weeks
body composition
Time frame: 12 weeks