Dietary Copper Intake and Bone Health: A Systematic Review and Meta-Analysis of Observational Studies

Studies evaluating habitual dietary copper intake and bone mineral density have garnered significant interest due to copper's indispensable role in collagen cross-linking and osteogenesis. These investigations, which employ dietary assessment tools alongside DXA measurements of skeletal sites, have nonetheless yielded heterogeneous results regarding the impact of copper consumption on bone health. Consequently, elucidating the nature and magnitude of this association is of paramount importance for both nutritional epidemiology and osteoporosis prevention. The review was conducted in accordance with PRISMA guidelines and registered in Prospero (CRD42024617075). Electronic literature searches were performed up to February 2025 in EMBASE, PubMed, OVID, Scopus, and Web of Science to identify observational studies assessing dietary copper intake and DXA-measured BMD, and study quality was appraised using the Newcastle-Ottawa Scale. Data were pooled via a generic inverse-variance random-effects model, with heterogeneity assessed by the Q test and I² statistic. A random-effects meta-analysis of three studies (n = 9059) found that higher dietary copper intake was associated with a modest but significant increase in lumbar spine BMD (MD 0.02 g/cm²; 95% CI 0.00-0.04; p = 0.04; I² = 36%), whereas a separate meta-analysis of four studies (n = 14,345) for hip BMD showed a similar MD of 0.02 g/cm² that did not reach significance (95% CI - 0.00-0.04; p = 0.07; I² = 74%). Higher dietary copper intake is modestly associated with increased lumbar spine BMD, while evidence for hip BMD remains inconclusive, underscoring copper's potential role in osteoporosis prevention.