Proteins and bone health.

ABSTRACT

Hip fracture consecutive to osteoporosis represents a major health problem in terms of both morbidity and financial burden for the community. Deficiency in nutritional elements appear to play a major role in the pathogenesis of osteoporosis and of fractures in elderly. Correction of an inadequate supply in both calcium and vitamin D can reduce bone loss and fracture incidence in elderly subjects. In addition, low protein intake could be particularly detrimental for the conservation of bone integrity with aging. Thus, in hospitalized elderly patients reduced protein intake is associated with lower femoral neck bone mineral density (BMD) and poor physical performance. Furthermore, state of malnutrition or undernutrition is often observed in elderly patients with hip fracture. In these patients, in who we detected very low femoral neck (BMD) at the level of the proximal femur, the self-selected intake of protein and energy was insufficient during their hospitalization. Interestingly, the clinical outcome after hip fracture was significantly improved by daily oral nutritional supplement normalizing the protein intake, documented as a reduction in both complication rate and median duration of hospital stay. Further studies showed that normalization of the protein intake, independently of that of energy, calcium and vitamin D, was responsible for this more favorable outcome, and could prevent further bone loss, at least at the level of weight-bearing cortical bone. In undernourished elderly subjects an increase in the protein intake, from low to normal, could be beneficial for bone integrity. This could act through an increase in the growth factor IGF-1 which has been found to decrease with aging.