Factors affecting bone density in young adults

A 14-y follow-up of 581 children who took part in a randomized controlled trial of the effect of a milk supplement on growth of children was conducted to investigate the supplement's effect on adult bone mineral content (BMC) and density (BMD). BMC and BMD of the nondominant forearm were measured by single-photon absorptiometry in 371 subjects (64%) aged 20-23 y, at a proximal site (shaft of radius and ulna) and at a distal site near the wrist. BMCs and BMDs tended to be higher in the intervention group (NS). Cross-sectionally, BMD was positively associated with body weight (P less than 0.01) in both sexes; inversely associated with alcohol consumption (P less than 0.05), and positively with manual occupation (NS) in men; positively associated with current intakes of calcium (P less than 0.05), vitamin D (P less than 0.01), and sports activity during adolescence (P less than 0.01), and inversely with parity (NS) in women. In multiple linear-regression analysis body weight and sports activity during adolescence were stronger determinants of female BMD than was diet.