Determinants of serum copper, zinc and selenium in healthy subjects

Background: We have investigated the association between serum copper, zinc and selenium concentrations, dietary intake, and demographic characteristics, including individual coronary risk factors, in healthy subjects. Methods: Serum copper, zinc and selenium were measured by atomic absorption spectrometry in 189 healthy subjects. Serum glutathione peroxidase and caeruloplasmin were also determined for each subject. A previously validated food frequency questionnaire was used to estimate the dietary trace element intake. Results: Male subjects had significantly lower serum copper (P < 0.001) and caeruloplasmin (P < 0.001), and higher serum zinc (P < 0.05) and zinc:copper ratio (P < 0.001) than female subjects. Significant differences were observed in serum copper and caeruloplasmin concentrations (P < 0.01) with age. Weak but significant associations between dietary trace elements and their serum concentrations were observed for zinc (r = 0.18, P = 0.02), copper (r = 0.17, P = 0.03) and selenium (r = 0.19, P = 0.02). Obese subjects had significantly lower serum concentrations of zinc (P < 0.05). In multifactorial analysis, dietary zinc (P < 0.05), serum high-density lipoprotein-cholesterol (HDL-C) (P < 0.05), diastolic blood pressure (P < 0.05) and age (P = 0.05) emerged as major predictors of serum zinc concentrations. The corresponding predictors for serum copper were C-reactive protein (CRP) (P < 0.001), serum HDL-C (P < 0.001), gender (P = 0.01), physical activity levels (P < 0.05) and dietary copper (P < 0.05). Serum selenium concentrations were predicted by serum total cholesterol (P < 0.01), serum CRIP concentrations (P < 0.05) and dietary selenium (P < 0.03). Conclusion: Serum copper, zinc and selenium concentrations are influenced by physiological conditions such as age, diet and gender. Their serum concentrations are also associated with coronary risk factors, including body mass index, levels of physical activity, serum HDL-C and CRP.