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

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 density 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 geno-typic 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.

Evaluation of Protein and Micronutrient Levels in Edible Cowpea (Vigna Unguiculata L. Walp.) Leaves and Seeds

“…Interestingly, the leaves of cowpea genotypes Apagbaala, Line 2020, Iron Gray, IT94D-437-1, and Omondaw were similarly very rich in Mn and B, as found for Fe and Zn. These results agree with the findings of Belane and Dakora (2012), and suggest that, with little effort, breeders can easily identify cowpea genotypes with the ability to accumulate high levels of the micronutrients Fe, Zn, Mn, and B in edible leaves for use by farmers to overcome trace element deficiency in Africa.…”

A review of the contribution of cowpea leaves to food and nutrition security in East Africa

“…Muchoki et al (2010) reported a reduction of 71.9% in the nitrate content of cowpea vegetables subjected to fermentation. The overall aim of the fermentation process has been to improve on the shelf-life of the cowpea leaves, while at the same time the nutritional quality has also been improved.…”

“…Cowpea leaves have antinutritional factors such as oxalates, phytates, and nitrates which are known to have negative impact on the nutrient intake of individuals (Muchoki et al, 2010;Oulai, Zoue, & Niamke, 2015). Optimal processing and preservation techniques should seek to reduce or minimize the accumulation of these antinutritional factors as a way of ameliorating the nutritional quality.…”

“…The overall aim of the fermentation process has been to improve on the shelf-life of the cowpea leaves, while at the same time the nutritional quality has also been improved. Muchoki et al (2010) reported a reduction of 71.9% in the nitrate content of cowpea vegetables subjected to fermentation. However, the fermentation techniques employed in these traditional practices are spontaneous and the product quality in terms of the nutritional and sensory is still varied and not optimal.…”

Screening Cowpea (<i>Vigna unguiculata</i> (L.) Walp.) Genotypes for Enhanced N<sub>2</sub> Fixation and Water Use Efficiency under Field Conditions in Ghana

“…However, due to variations in legume symbiotic performance resulting from genotypic differences and N 2 -fixing efficiency of the rhizobial symbionts, there is often the need to screen for improved N 2 fixation among legume germplasm [6] [7]. Of the many techniques used to estimate legume symbiotic performance, the 15 N natural abundance has so far been useful in quantifying N 2 fixation in field-grown legumes [8] [9]. This technique requires the estimation of the isotopic fractionation associated with N 2 fixation in the legume (so called B value), and the selection of reference plants to estimate the soil N uptake by the legume [10] [11].…”