This study will examine the health effects of calcium supplements in overweight adults.
Overweight adults often eat a diet low in calcium. Some studies have found low calcium intake
in people who have some of the medical problems often seen in overweight adults. This study
will see if extra calcium improves the health of overweight adults.
Volunteers in general good health 18 years of age or older who are overweight (body mass
index equal to or greater than 25 kilograms per square meter of body surface) may be eligible
for this study. Women who are pregnant or breastfeeding may not participate. The study
includes four visits, described below.
Visit 1
Volunteers will be screened for participation in the study with a medical history, physical
examination, and blood and urine tests. At home, they will collect a 24-hour urine sample;
fill out questionnaires to assess their average calcium intake; and record their food intake
for 7 days. Those enrolled in the study will continue with the next 3 visits.
Visit 2
Participants will complete a physical activity questionnaire, have their food diary reviewed,
and meet with a dietitian for nutritional counseling. Triceps fold thickness and waist and
hip circumferences will be measured three times. Body composition will be analyzed by a DEXA
study. For this procedure, the subject lies on a flat table while a small dose of X-rays is
passed through the body.
Participants will be randomly assigned to take either calcium carbonate (1500 mg/day) or
placebo capsules twice a day by mouth for 2 years. (The placebo looks like the calcium
capsules but contains no calcium.) They will receive a 6-month supply of study capsules
during visit 2 and return to NIH every 6 months for the next supply. They will also be sent
questionnaires by mail every 3 months to complete information about health problems and how
often the study capsules are being taken.
Visits 3 and 4
Visit 3 is scheduled after participants have taken the study capsules for 1 year; visit 4 is
scheduled after 2 years (the end of the study). At each of these visits, participants will
have a DEXA scan, blood and urine tests, blood pressure measurements, and measurements of
height, weight, waist and hip circumference. They will complete questionnaires about their
medical history, side effects of the study medications, dietary calcium intake, and physical
activity, and they will meet with one of the study investigators to talk about any concerns
regarding the study. At the fourth visit, participants will answer some additional questions
about their study participation and return the Diet History Questionnaire that was mailed to
them before the visit.
Phase:
Phase 3
Details
Lead Sponsor:
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)