Effect of dietary copper intakes on biochemical markers of bone metabolism in healthy adult males

Objective: To investigate the effects of changing from a medium (1.6 mg Cu/d) to a low (0.7 mg Cu/d) or a high (6.0 mg/d) Cu intake on biochemical indices of bone turnover in healthy adult males. Design: A longitudinal intervention trial. Setting: The study was conducted at the institute of Food Research, Norwich, UK. Subjects: Eleven healthy adult males aged 20-59 y were recruited from Norwich Research Park. Intervention: Subjects were given medium (1.6 mg/d), low (0.7 mg/d) and high (6.0 mg/d) intakes of Cu, in that order, over consecutive 8 week periods with a minimum of 4 week washout periods. On the last d of each dietary period fasting first void urine and blood were collected. Results: Serum caeruloplasmin or Cu (indices of Cu status), serum osteocalcin (biomarker of bone formation), urinary creatinine (Cr) were unaffected by dietary Cu intake. Urinary Pyr/Cr and Dpyr/Cr (biomarkers of bone resorption) were significantly increased (P < 0.05) (by 30% and 25% respectively), when subjects were switched from the medium to the low Cu diet and were significantly decreased (P < 0.05) (by 30% and 22% respectively), when subjects were switched from the low to the high Cu diet. Conclusion: The findings of the present study could have implications for bone health in individuals with marginal Cu intakes. Thus, further studies are warranted to better define the relationship of marginal Cu intakes to bone health.