Adolescent dairy consumption and physical activity associated with bone mass

Background. This study identifies key modifiable factors influencing Asian and White adolescent bone development. Cross-sectional analysis of baseline data of cohort. Methods. Three hundred and twenty-three girls were examined from age-eligible girls at Kaiser Permanente Oahu in Hawaii. Girlsʹ age, ethnicity, Tanner stage, 3-day diet record, level of physical activity, anthropometry, and calcaneal bone status were obtained by questionnaire and measurement, respectively. Lunar Achilles calcaneal was used to measure calcaneal bone mass. Multiple regression was used for analysis of factors influencing bone mass. Results. The mean age of adolescents was 11.6 ± 1.5 years. Girls were generally ethnically mixed; the mean Asian ethnic proportion was 48% while White ethnic proportion was 43% and other ethnic proportion was 10%. Multiple regression explained 40.8% and 25.6% of the variation in calcaneal broadband ultrasound attenuation (BUA) and speed of sound (SOS), respectively, in a model where age, weight, biacromial breadth, Tanner pubic hair stage, Asian ethnicity, dairy intake, and physical activity positively influenced bone mass. Conclusions. Tanner pubic hair stage, ethnicity, and biacromial breadth had the greatest influence on SOS; while physical activity, body weight, and dairy product intake had the greatest influence on BUA.