Journal of Bone and Mineral Research Vol. 28 Issue 7
Christopher J Gallagher MD1,*,
Prachi S Jindal MBBS1,
Lynette M Smith MS2
There is limited information on the effects of vitamin D on serum 25 hydroxyvitamin D in young people and none on African Americans. The main objective of this trial was to measure the effect of different doses of Vitamin D3 on serum 25 hydroxyvitamin D (25OHD) and serum PTH (parathyroid hormone) in young women with vitamin D insufficiency (serum 25OHD< 20ngml (50nmol/L). A randomized double blind placebo controlled trial of vitamin D3 was conducted in young Caucasian and African American women, age 25–45 years. 198 healthy Caucasian (60 percent) and African American (40 percent) women were randomly assigned to placebo, vitamin D3 400, 800, 1600 or 2400 IU daily. Calcium supplements were added to maintain a total calcium intake of 1200–1400 mg daily. The primary outcomes of the study were the final serum 25OHD and PTH levels at 12 months. The absolute increase in serum 25OHD with vitamin D 400, 800, 1600 and 2400 IU daily was slightly greater in African Americans than Caucasian women.
On the highest dose of 2400 IU the model estimated that mean 25OHD increased from baseline 12.4 ng /ml (95% CI 9.2–5.7) to 43.2 ng/ml (95%CI 38.2–8.1) in African Americans and from 15.0 g/ml (95% CI 12.3–7.6) to 39.1 ng/ml (36.2–2.0 ng/ml) in Caucasian women.
There was no significant effect of vitamin D dose on serum PTH in either race but there was a significant inverse relationship between final serum PTH and serum 25OHD.
Serum 25OHD exceeded 20 ng/ml in 97.5% of Caucasians on the 400 IU dose and between 800–1600IU for African Americans.
The Recommended Dietary Allowance (RDA) suggested by the Institute of Medicine for young people is 600 IU daily.
The increase in serum 25OHD after vitamin D supplementation is similar in young and old, and in Caucasian and African American women.
|African American||12.4 ng||43.2 ng|
|Caucasian||15.0 ng||39.1 ng|
Need even more vitamin D if
- Indoors a lot
- taking a drug which lowers vitamin D levels
- have a condition which Prevents Adsorption in the gut
and more - details at Many reasons why vitamin D deficiency has become epidemic