Effect of Tea and Coffee Consumption on Blood Levels of Some Heavy Metals and Trace Metals

Abstract

In the present study, the content of Cd, Pb, Hg, Zn, Cu, and Se in blood following extended consumption of tea and coffee was determined. By random sampling method, sixty participants were selected for this study and grouped into 20 tea consumers, 20 coffee consumers and 20 controls. They were administered tea and coffee beverages respectively daily for 30 days, after which venous blood samples were collected from each participant into lithium heparin container. Blood Pb, Cd, Hg, Cu, Zn and Se were determined by employing Flame Atomic Absorption Spectrophotometry. All data generated were used to perform statistical analysis employing SPSS version 21. Blood Cd, Pb, Hg and Se were significantly higher (p=0.005, p=0.003, p=0.001 and p=0.048, respectively) in tea Consumers compared with controls, while there were no significant difference in blood levels of Cu and Zn (p=0.923 and p= 0.784 respectively) in tea Consumers compared with controls. Blood Cd, Pb, Hg, Zn and Se were significantly higher (p=0.001, p=0.000, p=0.012, p=0.037 and p=0.006 respectively) in Coffee Consumers compared with Controls. There was no significant difference in blood Cu (p=0.222) in Coffee Consumers compared with Controls. There were no significant differences in blood levels of Cd, Pb, Hg, Cu, Zn and Se (p=0.154, p=0.459, p=0.662, p=0.226, p=0.080 and p=0.705 respectively) in Tea Consumers compared with Coffee Consumers. There were significant negative correlations of blood Pb with Hg and Cu(r=-0.451, p=0.046 and r=-0.697, p=0.001 respectively) in Tea Consumers. There were significant negative correlations of blood Pb with blood Cu and Zn (r=-0.656, p=0.002 and r=-0.690, p=0.001 respectively) and significant positive correlation of Pb with Hg (r=0.538, p=0.017) in Coffee Consumers. These findings have shown that Tea and Coffee Consumption may be associated with higher blood levels of Pb, Cd, Hg and Se; hence, caution should be applied considering the deleterious effects of heavy metals.