Bone Gain in Young Adult Women

Objective.—To test whether bone mass increases in healthy nonpregnant white women during early adult life after cessation of linear growth; and to test whether various self-chosen levels of physical activity and nutrient intake or use of oral contraceptives influences this increase in bone mass. Design.—Longitudinal prospective study of up to 5 years of 156 healthy college-aged women full-time students attending professional schools in universities in the Omaha, Neb, area. Setting.—University medical center. Participants.—A convenience sample of healthy women students from Omahaarea professional schools. Any candidate with an illness, condition, or medication (except oral contraceptives) thought to affect general health or bone mass was excluded. Interventions.—None. Outcome Measures.—Clinical and family histories of disease, particularly osteoporosis; oral contraceptive use; bone mineral densities of the spine, forearm, and total body by dual- and single-photon absorptiometry; estimates of nutrient intake by repeated 7-day diet diaries; and measures of physical activity using a physical activity monitor. Results.—The median gain in bone mass for the third decade of life, expressed as a percentage per decade, was 4.8% for the forearm, 5.9% for lumbar bone mineral content, 6.8% for lumbar bone mineral density, and 12.5% for total body bone mass (P