Contribution of minerals from fresh kidney bean leaves and grains in meals consumed in East, South and Central Africa

Varieties of legumes are recognized as an important source of protein and dietary minerals by a number of ethnic groups in East, South and Central Africa. Among the legume that is preferred by most Africans are the bean varieties. Beans are consumed in many forms: the young leaves, green pods, and fresh bean grains are used as vegetables; dry bean grains are used in various food preparations, and both are used as relish or side dishes together with the staple food. Apart from alleviating food insecurity, the bean leaves, green bean pods and fresh bean grains are good sources of micronutrients especially iron and zinc. Thirty eight varieties of beans deemed to be rich in minerals iron and zinc collected from a number of locations in East and Central Africa were brought from University of Nairobi and multiplied at Sokoine University of Agriculture, Morogoro. Bean leaves and fresh beans grains were picked for analysis after the plants reached three weeks and two months, respectively. Iron and zinc content was determined by atomic absorption spectrophotometer after ashing the samples. Analysis showed that leaves had significantly (P<0.05) more iron than the fresh bean grains. For bean leaves, Maharagi soja had the highest level of iron (1653.9 mg/100g) followed by Nain De Kiondo (1061.1 mg/100g). Similarly, Maharagi soja had the highest level of zinc (40.8 mg/100g), followed by Kiangara (40.5 mg/100g). Variety HRS 545 fresh bean grains, had the highest level of iron (1114.0 mg/100g) followed by Ituri Matata (983.4 mg/100g) while highest zinc content was found in HRS 545 (41.1 mg/100g) followed by RWR 10 (41.1 mg/100g). These levels of minerals are significantly higher than the average amount found in dry bean grains (Fe 5.6 – 8.0 mg/100g) and (Zn 1.7 - 2.0 mg/100g). Creating more awareness and encouraging the utilization of bean leaves and fresh bean grains will contribute in alleviating micronutrient deficiencies especially among the vulnerable groups such as children, pregnant and lactating women, and resource-poor families.