Comparative study of trace metal (Cd, Cr, Cu, Fe, K, Mg, Na, and Zn) contents of local and imported vegetable oil brands consumed in Nigeria

This paper reports the results of the study of Cd, Cr, Cu, Fe, K, Mg, Na, and Zn contents of 20 branded vegetable oil (10 local and 10 foreign brands) samples purchased from markets in Abia State, South-eastern Nigeria. The metals were determined using atomic absorption spectrophotometer after acid digestion. The metals (mg/kg) determined for local brands of vegetable oil varied as follows: 64.2-443 for Na; 0.005-101 for K; 12.9-222 for Mg; ND-1.8 for Cr; 0.22-4.99 for Cu; 50-425 for Fe and 9.1-25 for Zn. For the foreign brands, the concentration (mg/kg) varied from 113-452 for Na; 0.002-103 for K; 46-177 for Mg; 0.015-1.67 for Cr; 0.69-3.44 for Cu; 125-413 for Fe and 9.1-31.8 for Zn. The Cd contents were generally below detection limit and only two foreign brands had detectable Cd concentrations (0.012 and 0.602 mg/kg). On the overall, iron concentration was higher than other trace metals in the examined vegetable oils. Apart from Cd content, the metals concentrations of investigated local brands of vegetable oil compared well with their foreign counterparts. The results of this study showed that the estimated intake levels for these metals, when compared with set safety levels, should pose no risk to human health.

Author(s): Innocent C. Nnorom and Ugochukwu Ewuzie*

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