Intervention
Study Intervention
Participants are randomized in a strati-
fied (by site, BMI, and race) and blocked
fashion and in a one-to-one ratio to receive
once daily either a single softgel of
vitamin D3 (cholecalciferol 4,000 IU) or
matching placebo for the duration of the
study. Assignment is double masked.
The vitamin D3 and placebo pills are prepared
by Tishcon Corp. in accordance
with U.S. Pharmacopeia standards and
Good Manufacturing Practices and
shipped to the drug distribution center
(Veterans Affairs Cooperative Studies
Program, Albuquerque, NM) in bulk
where they are packaged into bottles
with enough pills for an 8-month period
and then shipped to each site for storage
before distribution to participants.
Both the manufacturer and the drug distribution
center perform quality control
analyses on each lot, including assaying
for the amount of the active ingredient
(vitamin D3). In addition, the drug distribution
center performs periodic potency
testing to ensure that the amount of active
ingredient is within specified limits
throughout its use