Dietary protein has been linked to improvements in bone microstructure, but the relation between microstructure and strength is not clearly defined. A new study investigated the effects of dietary protein on both microstructure and bone strength and found positive correlation between both factors.
Consuming protein is essential for building and maintaining bone. To combat osteoporosis, elevated protein diets are often prescribed to slow the progression of the disease. However, though the consistency and microstructure of bones have been linked to dietary protein, no link has been made to bone strength. The resistance of bone to fracture can be estimated through finite element analysis (FEA) using high-resolution imaging. FEA is a computerized simulation of how matter will react when under load. Using high-resolution images of bone, specific properties can be applied to the simulation and the stress the bone experiences under force can be estimated.
While no link has been established between dietary protein and bone strength, it is also unclear whether the protein source has an effect on bone strength and structure. There have been inconsistent associations for animal, plant, and dairy proteins’ contributions to bone health. The scientists of a new study hypothesized that proteins which provide calcium as well, such as dairy, would be most beneficial to bone strength and microstructure.
In this study published in The American Journal of Clinical Nutrition, Durosier-Izart et al. investigated the association between dietary protein from various sources with bone microstructure and bone strength. 746 healthy post-menopausal women underwent the study. A face to face questionnaire with a dietician was used to obtain data such as exercise history, tobacco use, fracture history and dietary information. X-rays and CT scans provided bone microstructure information, as well as parameters for the FEA, which determined bone strength.
After statistical analysis, it was determined that higher protein intake, particularly from animal and dairy sources, were associated with greater bone strength and improved bone microstructure. These relations remained true after accounting for weight, height, physical activity, menopause duration and calcium intake. There was no negative effect on bone health at high levels of protein intake. The dairy-specific results of this study support previous findings that dairy consumption reduces biochemical markers of bone loss and over a longer duration, can attenuate bone loss and even increase bone mineral density of the femur and hip. The large, homogenous population of the study is seen as a strength, while the questionnaire based dietary information and the potential for confounding are possible limitations.
In conclusion, Durosier-Izart et al. found that bone strength and microstructure improved with increased dietary protein intake. This held particularly true for dairy proteins, which also provide calcium. These findings could be used in the future to alter dietary regimens prescribed to those at risk of bone fragility.
Written By: Wesley Tin, BMSc