Dietary Protein: An Essential Nutrient For Bone Health

Abstract

Nutrition plays a major role in the development and maintenance of bone structures resistant to usual mechanical loadings. In addition to calcium in the presence of an adequate vitamin D supply, proteins represent a key nutrient for bone health, and thereby in the prevention of osteoporosis. In sharp opposition to experimental and clinical evidence, it has been alleged that proteins, particularly those from animal sources, might be deleterious for bone health by inducing chronic metabolic acidosis which in turn would be responsible for increased calciuria and accelerated mineral dissolution. This claim is based on an hypothesis that artificially assembles various notions, including in vitro observations on the physical-chemical property of apatite crystal, short term human studies on the calciuric response to increased protein intakes, as well as retrospective inter-ethnic comparisons on the prevalence of hip fractures. The main purpose of this review is to analyze the evidence that refutes a relation of causality between the elements of this putative patho-physiological "cascade" that purports that animal proteins are causally associated with an increased incidence of osteoporotic fractures. In contrast, many experimental and clinical published data concur to indicate that low protein intake negatively affects bone health. Thus, selective deficiency in dietary proteins causes marked deterioration in bone mass, micro architecture and strength, the hallmark of osteoporosis. In the elderly, low protein intakes are often observed in patients with hip fracture. In these patients intervention study after orthopedic management demonstrates that protein supplementation as given in the form of casein, attenuates post-fracture bone loss, increases muscles strength, reduces medical complications and hospital stay. In agreement with both experimental and clinical intervention studies, large prospective epidemiologic observations indicate that relatively high protein intakes, including those from animal sources are associated with increased bone mineral mass and reduced incidence of osteoporotic fractures. As to the increased calciuria that can be observed in response to an augmentation in either animal or vegetal proteins it can be explained by a stimulation of the intestinal calcium absorption. Dietary proteins also enhance IGF-1, a factor that exerts positive activity on skeletal development and bone formation. Consequently, dietary proteins are as essential as calcium and vitamin D for bone health and osteoporosis prevention. Furthermore, there is no consistent evidence for superiority of vegetal over animal proteins on calcium metabolism, bone loss prevention and risk reduction of fragility fractures.

Impacto dos nutrientes na saúde óssea: novas tendências

“…O excesso de lipídeos pode inibir a secreção de GH, pelo aumento nos níveis de ácidos graxos plasmáticos livres (10)(11) .…”

Recovery of spaceflight-induced bone loss: Bone mineral density after long-duration missions as fitted with an exponential function

“…As displayed in figures of postflight BMD changes, some crew members recover within the first year after return while others do not recover until much later. Factors that contribute to this variability in recovery are likely to include nutrition [15,16], skeletal muscle reconditioning [17], and genetics [18,19]; some of these factors may delay the ability and motivation of crew members to become ambulatory and thus mechanically load their skeletons. It is interesting to note that two of the three outliers for BMD loss in the proximal femur (greater than a 15% deficit in femoral neck and trochanter) were older than the average age of, or in space longer than the average duration for, long-duration crew members; the missions corresponding to these outliers also represented their first long-duration flight.…”

Importance of Recognition of Osteoporosis and the Radiologic Diagnosis Using DEXA Technique

“…It is also made up of collagen, which forms the structural framework of bone. The loss of mineral content of the bone is referred to as a loss of bone mineral density in the bone, so osteoporosis when progress over time, leads to thinning and deterioration of bone tissue with loss of calcification and density [4,5]. This can cause the bone to become fragile and break.…”