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Obese may need 40 percent more vitamin D - RCT Aug 2014

The Vitamin D Dose Response in Obesity.

Endocr Pract. 2014 Aug 6:1-25. [Epub ahead of print]
Dhaliwal R, Mikhail M, Feuerman M, Aloia JF.
Bone Mineral Research Center, Winthrop University Hospital, Mineola, New Yor

Objective: Prevalence of vitamin D inadequacy is high in obese individuals. Determining the response of serum 25-hydroxyvitamin D [25(OH)D] to vitamin D3 supplementation in obese and non-obese individuals may lead to concurrent recommendations for optimal vitamin D intake in these populations. The objective of this study was to determine the dose response of vitamin D3 in subjects with body mass index ≥ 35 kg/m2.

Design and Methods: Randomized, double-blind, placebo-controlled study. This study is an extension of our previous study of vitamin D dosing in healthy adults. After an assessment of baseline 25(OH)D levels, participants were randomized to a vitamin D supplementation arm (100 μg daily if baseline 25(OH)D was < 50 nmol/L, or 50 μg daily if baseline 25(OH)D was ≥ 50 nmol/L) or placebo arm.
Subjects with baseline 25(OH)D level ≥ 80 nmol/L were excluded from the study. Two months following randomization, a repeat 25(OH)D measurement was done.

Results: Final analysis included 25 subjects (14 placebo, 11 active). At two months, serum 25(OH)D concentration increased to a mean of 75 nmol/L in the active group. Mean slope (i.e. vitamin D3 response), defined as 25(OH)D change/baseline dose, was 0.398 nmol/L/μg/d.

Conclusion: The dose response of vitamin D3 (slope) in obese subjects was significantly lower (p < 0.03) at 0.398 nmol/L/μg/d compared to the slope in the previous study of healthy subjects (0.66 nmol/L/μg/d). These results suggest that obese individuals may require 40% higher vitamin D intake than non-obese individuals to attain the same serum 25(OH)D concentration.

PMID: 25100366

Summary by VitaminDWiki

4,000 IU daily for 2 months if initially < 20 ng
2,000 IU daily for 2 months if initially 20– 32 ng
At 2 months the result was a mean of 30 ng

Question by VitaminDWiki

Why did they not use a loading dose?
Strongly suspect that the vitamin D levels were still rising at the 2 month conclusion without a loading dose.

See also VitaminDWiki

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