NUTRIENTS, BODY-COMPOSITION AND EXERCISE ARE RELATED TO CHANGE IN BONE-MINERAL DENSITY IN PREMENOPAUSAL WOMEN

This study determined relationships among total energy intake, nutrien t intake, body composition, exercise group status, and annual rates of change (slopes) in bone mineral density in 66 Caucasian premenopausal women (mean age, 34.4 +/- 2.7) taking calcium supplements. Body compo sition components measured by dual-energy X-ray absorptiometry include d fat mass, soft tissue lean mass, and bone mineral density (g/cm(2)) of total body, spine (lumbar vertebrae 2-4), and three femur sites mea sured at baseline, 5, 12, and 18 mo. Nutrients were not significant va riables in regression models predicting bone mineral density slopes (r ates of change) at any femur site. The only significant variable in mo dels predicting Ward's triangle bone mineral density slope was the ini tial fat mass and, for trochanter, exercise. Significant variables (P < 0.05) in models predicting total body bone mineral density slope inc luded the initial fat mass and fat mass slope plus either vitamin A, c arotene, fiber, magnesium, or phosphorus (R(2) from 0.31 to 0.25) and fat mass slope plus sodium (R(2) = 0.24). The significant variable in the model predicting L(2-4) slope was energy intake (R(2) = 0.17, P < 0.05). We conclude that nutrient intake, exercise, and body compositio n are related to bone mineral density rate of change and that relation s among these variables vary by bone site.