Adolescents: At increased risk for osteoporosis?

Perhaps the most important factor in the primary prevention of osteoporosis is the attainment of an optimal peak bone during adolescence, In addition to endogenous factors, such as genetic and ethnic background, environmental factors such as dietary habits, physical activity and sex hormone therapy, influence the accretion of bone mass during this critical period of skelet al growth, First, calcium dietary intake in adolescents is generally well l ess than the current recommended RDA of 1200 mg/day, Multiple studies of ch ildren and adolescents have demonstrated increases in bone mass with dietar y calcium supplementation. Second, regarding physical activity, the overall impression is that a moderate amount of particularly weight-bearing exerci se has a positive impact on bone, There appears, however, to be a threshold of intensity of physical activity over which a negative impact on bone occ urs, particularly when the exercise is of an anaerobic nature or occurring in very thin, amenorrheic participants, Third, previous research suggests t hat the various forms of hormonal contraception exert differing effects on bone mass in adolescents, with levonorgestrel implants and combined oral co ntraceptives may be associated with a more positive effect on bone mass com pared with that observed with depot medroxyprogesterone acetate, From a cli nical perspective, approaches to optimizing peak bone mass in adolescents w ould include increasing calcium intake, whether in the form of dairy produc ts, fortified foods, or supplements as well as encouraging participation at a moderate level, in weight-bearing exercise. Last, in adolescents with ex tensive risk factors and predicted long duration of use, subdermal implants or combined oral contraceptives may be the optimal hormonal methods of bir th control.