The impact of protein diet on bone density in people with/without chronic kidney disease: An analysis of the National Health and Nutrition Examination Survey database

Introduction High protein diet is essential for the healthy state of bones. Low protein diet is often recommended to patients with chronic kidney disease (CKD). Risk factors for femoral neck fractures are clear, but trochanteric and intertrochanteric fractures may have different risk factors. In this study, we determined the association between bone density at different femoral areas and a number of protein diets in patients with and without CKD. Methods We extracted information from the database of the National Health and Nutrition Examination Survey (NHANES), 2005–2010. We have basic variables, metabolic diseases, and bone density of different femoral areas and separated them according to different protein diets (<0.8 g/kg/day, 0.8–1.0 g/kg/day, 1.0–1.2 g/kg/day, and ≥1.2 g/kg/day). The differences of differential femoral areas were analyzed according to different protein intakes in subjects with and without CKD. Results A total 12,812 subjects were analyzed. Among all four subgroups of protein diets, we found statistically significant differences over bone mineral density (BMD) or T scores (p < 0.0001) among all femoral areas. For total femoral BMD and T scores, the higher the protein intake, and the higher the bone BMD and T scores were noticed (p < 0.0001). We found similar relationship in the trochanter and intertrochanteric bone areas, but not in the femoral neck area. For the femoral BMD, higher protein diets led to higher BMD in the femoral neck, trochanter, intertrochanteric, and total femoral areas (p = 0.032, 0.0036, 0.008, and 0.0039, respectively). Such increased BMD benefits of higher protein diet were not found in CKD patients. Conclusions Higher protein diets led to higher femoral BMD only in subjects without CKD. CKD patients did not benefit in developing higher femoral BMD and those with Low protein diet did not reduce their femoral BMD. CKD was found to be a risk factor for low BMD in the intertrochanteric bone region.