[Modifying bone mass in child and adolescent: why?].

Osteoporosis is a major public health problem with an increase of its prevalence with age and growing consequences because of the increase of life expectancy. Peak bone mass which corresponds to the amount of bony tissue present at the end of skeletal maturation, is a major determinant of the risk of fractures, such as those observed at the radial, vertebral, or femoral sites in osteoporotic patients. Therefore, strategies of primary prevention of osteoporosis and associated fractures consist in increasing bone mass acquisition during skeletal growth. Physical activity and some nutrients such as calcium and proteins may influence positively the trajectory of bone mass acquisition and therefore increase peak bone mass.