Rationale
Cholecalciferol (D3) was chosen over ergocalciferol
(D2) because supplementation
with D3 may result in a greater and
more sustained increase in blood
25OHD concentration, D2 may be less
effective than D3, and vitamin D3 is the
most commonly consumed vitamin D
formulation. The dose being tested in
this study (4,000 IU/day) provides an appropriate
balance of safety and efficacy
in terms of obtaining a substantial difference
in blood 25OHD concentration between
the active and placebo groups