Osteoporosis, Nutrition and Adolescence

Osteoporosis is a worldwide health problem characterized by low bone mineral density and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures. Skeletal bone is maintained by the continuous process of bone remodeling by osteoclasts, cells that break down bone, and osteoblasts, cells that rebuild bone. An imbalance between bone resorption and accrual derives to overall bone loss, which in time leads to osteoporosis (Schettler & Gustafson, 2004). After the third decade of life, the bone mass naturally declines approximately 1-2% per year in women, and 0.3-1% per year in men, leading to losses of 30-50% of their initial bone mass in women and 20-30% in men during their lifetime (Riggs & Melton, 1986). As a consequence, both men and women may develop osteoporosis, maybe the most common chronic disability of postmenopausal women. However, osteoporosis should not be considered solely as adult disease, since bone health must be a lifelong concern, with special focus on the adolescent years (Schettler & Gustafson, 2004). In this sense, Kreipe (1992) suggested that “senile osteoporosis is a pediatric disease”. Osteoporosis in adolescence may be a primary or secondary consequence of diseases or disorders genetic but, in addition, it may be induced by erroneous lifestyle habits, including poor dietary habits, insufficient exposure to sunlight and low physical activities (Campos et al., 2003). The primary forms of osteoporosis in adolescents are relatively rare, and some of them are familiar or genetically determined. In this group may be included the osteogenesis imperfecta, a form of osteoporosis because of bone fragility which is characterized by weak bones that fracture easily, and the idiopathic juvenile osteoporosis, a rare disease associated with a negative calcium balance and characterized by repeated fractures (Bianchi, 2007). The secondary forms of osteoporosis result as a consequence of diseases associated with low bone mass and increased risk of fractures, such as neuromuscular disorders, chronic or endocrine diseases, and inborn errors of metabolism. Moreover, the treatment of some of these diseases may be associated to osteoporosis since several medications such as glucocorticoids, anticoagulants or anticonvulsant drugs can be negatively related to bone metabolism (Bianchi, 2007; Campos et al., 2003). On the other hand, conditions that result in pubertal retardation in adolescents such as anorexia nervosa or amenorrhea induced by exercise, can also be highlighted as causes of osteoporosis in this stage of life. Although osteoporosis is not common among adolescents, adolescence is a key factor on the development of this disease in the adult age. It has been reported that, probably, the most important factor in the primary prevention of osteoporosis is the attainment of an optimal