Aims: The important trace elements, copper and selenium, have diverse effects on human health. Although both have important roles in living tissues, these trace elements are toxic at high levels. While it is known that these elements are key constituents of various enzymes and proteins essential for maintaining physiological health, links between levels of dietary intakes, particularly for copper, and bone health in humans remain uncertain. This study aimed to investigate whether dietary intakes of copper and selenium are associated with BMD in women.
Methods: Dietary intakes of copper and selenium were assessed for 575 women in the Geelong Osteoporosis Study, using a detailed semi–quantitative food frequency questionnaire in conjunction with nutrition composition databases. Participants taking oral multivitamin preparations were excluded from analyses; 522 participants (ages 20-88y) met eligibility criteria. BMD at multiple skeletal sites was measured by dual energy x-ray absorptiometry (Lunar DPX-L). Separate multivariable regression models were developed to identify associations between copper and selenium intakes and BMD, after adjustments for age, anthropometry, other dietary factors, medication use and lifestyle factors.
Results: Median (IQR) daily intake for copper was 1.5mg (1.2-1.9) and for selenium, 72μg (57-90). Lowest tertiles corresponded to copper <1.4mg and selenium <58μg. Low intakes (lowest tertile versus pooled upper tertiles) of copper and selenium were consistently associated with lower BMD at multiple skeletal sites. Fully-adjusted models identified small but statistically significant differences in BMD, ranging from 1.8% to 4.0% for low copper intakes and 1.4% to 4.0% for low selenium intakes.
Conclusion: Low dietary intakes of copper and selenium were both independently associated with lower BMD, at least in this sample of women. The results contribute to the evidence base for informing dietary recommendations for these trace elements with respect to their contributions to optimal bone health.