Family Milk Product Two-year Dose-response Study to Enhance Bone Health

The final stages in the development of peak bone mass (PBM) reside in late adolescence or early adulthood and are critical in the achievement of bone health. Optimization of PBM and maintenance of bone mineral density (BMD) are the best population health strategies in the primary prevention of osteoporosis. Diet and activity are key lifestyle factors in the primary prevention of osteoporosis as recognized in Canada's Food and Activity Guides. Dietary Reference Intakes are evidence-based regarding nutrition and bone health with a focus on calcium and vitamin D; yet the Food Guide and health behaviors are reliant on actual foods. The number of recommended servings of milk and alternatives varies by age with average intakes estimated to be below targets for all Canadians \> 9 y of age. This is especially concerning during development of PBM. Therefore, the global objective is to generate high-level evidence that dietary intervention with milk and milk products will enhance PBM in young men and women and maintenance of BMD in their parents. The primary objective is to demonstrate in healthy young men and women (14-18.9 y at baseline) with habitually low usual milk and milk product intakes that intervention with greater milk and milk product consumption improves lumbar spine BMD in a dose-response manner over 2 y (while accounting for body size, physical activity, demographics and age). Healthy young men and women will be recruited and screened for usual intake of milk and milk products. Those with low intakes \< 2 servings of milk or milk products will be randomized (stratified by sex and age) to 1 of 3 groups for the RCT (n=10090/group): maintain usual low intakes (\<1 serving), improved intakes (average of 2 servings/d) or recommended intakes (≥3 servings/d) of milk and milk products. A manualized motivational interviewing framework will be used for the interventions. Those meeting recommendations at screening will form a longitudinal cohort for 2 y. Key measurements