Copper content of staple seeds and grains grown in Kanam local government area, Nigeria

Copper is a trace mineral that plays an important role in human metabolism, largely because it allows many critical enzymes to function properly. Little is known of copper content of Nigerian foods. In this paper, copper contents of several typical Nigerian foods were determined. The samples were collected from Kanam of Plateau State in central region of Nigeria. The samples were wet-ashed according to the protocol of Hill et al. (Anal Chem 55:2340-2342, 1986).Concentrations of copper in the samples was determined using inductively coupled-mass spectrophotometry. There is, for each crop, a wide variation in copper content. The highest copper content was found in cowpea, Vigna unguiculata (16.95 μg/g of dry weight). Lowest copper content was found in white maize and in yellow maize (Zea mays), with values 1.23 μg/g and 1.38 μg/g of dry weights, respectively. Other foods, such as white sorghum, red sorghum (Sorghum bicolor), millet (Pennisetum glaucum), and groundnuts (Arachis hypogea) had copper contents varying from 2.22 to 11.81 μg/g. These values are well below the supplemental values of 50 mg/day that could interfere with zinc absorption. Thus, among the staple foodstuffs of the areas sampled, cowpea appears to be the richest source of dietary copper followed by groundnut while the two maize varieties are the poorest.