Roles of diet and physical activity in the prevention of osteoporosis.

In recent years, much attention has been directed toward the prevention of osteoporosis, since this disease has become a leading cause of morbidity and mortality in elderly women. Research has demonstrated that the prevention of osteoporosis and osteoporosis-related fractures may best be achieved by initiating sound health behaviors early in life and continuing them throughout life. Evidence suggests that osteoporosis is easier to prevent than to treat. In fact, healthy early life practices, including the adequate consumption of most nutrients, regular physical activity, and other health behaviors, contribute to greater bone mineral measurements and optimal peak bone mass by the fourth decade of life of females, and, perhaps, also of males. Several reports have shown that the adequate consumption of nutrients, calcium in particular, during the pre-pubertal and early post-pubertal years of females contribute to increased peak bone mass. Indeed, skeletal benefits from long-term calcium supplementation have been reported for females at practically every period of the life cycle. Vitamin D, which may be either consumed or produced endogenously through the action of sunlight, promotes calcium absorption and thereby enhances bone mineralization. Thus, the adequate consumption of calcium, in conjunction with vitamin D, in early life will likely optimize peak bone mass, and adequate intakes of these two nutrients should continue through the remainder of life to help maintain bone mass. On the other hand, excess phosphorus consumption may deter bone mineral accrual because of the resultant elevation of serum parathyroid hormone levels. Additionally, high intakes of protein, sodium, and caffeine may decrease bone mineral mass through increased urinary excretion of calcium. Vitamin K may also have an important positive effect on the development and maintenance of bone through its role in promoting carboxylations of the matrix protein, osteocalcin. In conclusion, the prevention of osteoporosis needs to begin during the pre-pubertal years and it should be continued throughout life. Bone mass can better be maintained later in life through adequate consumption of several nutrients with specific roles in calcium and bone metabolism, regular physical activity, and the practice of a healthy lifestyle. Mechanisms through which the nutrients and exercise affect bone mass will be explored.