The Variability of 25-hydroxyvitamin D Response From Crystalline 25-hydroxyvitamin D3

The Variability of 25-hydroxyvitamin D Response From Crystalline 25-hydroxyvitamin D3 Compared to Native Vitamin D3: A Short Term Pharmacokinetic Study

The investigators hypothesize that native vitamin D will have more variability in 25(OH)D dose response when compared to a given equipotent dose of 25-hydroxyvitamin D3. This will be a single blind, active control, pharmacokinetic study of 625 μg 25(OH)D given orally or 2500 μg native vitamin D given orally.

Single blind, active control, pharmacokinetic study of 625 μg 25(OH)D given orally or 2500 μg native vitamin D given orally.

Inclusion Criteria:

• Ten men and women in each group,
• aged 20-60.

Exclusion Criteria:

• History of hypercalcemia,
• vitamin D supplement use > 800 IU daily,
• BMI > 30,
• gastrointestinal malabsorption (from celiac sprue, colitis, surgery, etc.), kidney disease or liver disease,
• use of steroids in any form,
• anticonvulsants,
• antibiotics,
• acute illness, or
• vacation planned to "sunny climate"