Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials and prospective cohort studies
PubMed 28404575 · doi:10.3945/ajcn.116.145110
What was done
Searches across five databases through October 2016 identified randomized controlled trials (RCTs) and prospective cohort studies evaluating the effect of high versus low dietary protein intake, alone or combined with calcium and/or vitamin D (Ca±D), on adult bone health outcomes. Two reviewers independently conducted screening, data extraction, and risk of bias assessments. Random-effects meta-analyses were performed for outcomes reported in four or more RCTs.
What was found
The review included 16 RCTs and 20 prospective cohort studies with an overall medium risk of bias. Higher protein intake was associated with a small protective effect on lumbar spine (LS) bone mineral density (BMD) compared with lower protein intake (net percentage change: 0.52%; 95% CI: 0.06%, 0.97%; I²: 0%; n = 5 RCTs). No significant effects were observed for total hip, femoral neck, or total body BMD, nor for bone biomarkers. Limited evidence showed no effect of protein with Ca±D on LS BMD, total hip BMD, or forearm fractures, with insufficient evidence for femoral neck BMD and overall fractures. No adverse effects of higher protein intake were observed.
Why it matters
This review refutes historical concerns that high protein intake damages bone health, demonstrating instead neutral to slightly beneficial effects on lumbar spine density in adults.
Limits
The included studies carried an overall medium risk of bias, and significant heterogeneity was noted. The positive lumbar spine finding was derived from only five RCTs with a very small effect size (0.52% net change), and data on clinical fracture outcomes and nutrient interactions (calcium/vitamin D) were insufficient. Residual confounding could not be excluded in the observational cohort data.
Cited by
- supports There is no scientific evidence that high protein intakes cause kidney damage or reduce bone density in healthy individuals.