Elevated Concentrations of Dietarily-Important Trace Elements and Macronutrients in Edible Leaves and Grain of 27 Cowpea (Vigna unguiculata L. Walp.) Genotypes: Implications for Human Nutrition and Health

Alphonsus K. Belane, Felix D. Dakora

Department of Chemistry, Tshwane University of Technology, Pretoria, South Africa..
Department of Crop Science, Tshwane University of Technology, Pretoria, South Africa;.

DOI: 10.4236/fns.2012.33054                

Abstract

Legumes are a good source of calories, protein and mineral nutrients for human nutrition and health. In this study, the edible leaves and grain of 27 field-grown cowpea genotypes were assessed for trace elements and macronutrient den-sity at Manga in the Sudano-Sahelian zone of Ghana in 2005 and 2006, using inductively coupled plasma-mass spectrometry. The genotypes differed markedly in their accumulation of trace elements and major nutrients in edible leaves and grain. Except for P, the concentrations of K, Ca, Mg, S and Na were much higher in edible cowpea leaves than grain in 2005. A similar pattern was observed for Ca, Mg, S, Na in 2006. However, more dramatic variations were found in the micronutrient concentrations between edible cowpea leaves and grain. The levels of the trace elements Fe, Cu, Zn, Mn and B were sometimes 2- to 20-fold greater in leaves than grain of cowpea. Furthermore, there were strong genotypic differences in mineral density of cowpea leaves and grain. For the major nutrients, for example, IT93K-2045-29 and IT90K-59 accumulated greater concentrations of P, K, Ca, S and Na in both edible leaves and grain in 2006, while ITH98-46, which showed the least macronutrient density, exhibited the highest concentrations of Fe, Zn, Cu, Mn and B in edible leaves, as well as Fe, Cu and Mn in grain. These results have implications for cowpea breeding, as well as for human nutrition and health.

Keywords

Calories; Protein; Trace Elements; Macronutrients; Nutrition; Ontogeny

Conflicts of Interest

The authors declare no conflicts of interest.

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