Germplasm improvement has also contributed to improved diets through Quality Protein Maize (QPM), containing more lysine and tryptophan, which is being disseminated in Africa, in particular in Ghana. Quality Protein Maize is used for weaning diets and in poultry and pig feed. Normal maize protein is deficient in these two essential amino acids, which can be supplemented by consuming milk, meat or beans. As the latter option is often not within the reach of poor families, Quality Protein Maize can improve the health of people and livestock. Consumer preference for relatively soft grain maize has contributed to the success of Quality Protein Maize in Ghana (CIMMYT, 2002). Quality improvement of grains with respect to specific characteristics should be balanced with the possible trade-offs in terms of yield, disease and pest resistance and consumer acceptability.
Various initiatives are underway to increase the nutritive value of food crops, including high-iron beans, high-betacarotene maize, high-iron rice, high-vitamin A or golden rice and orange-flesh sweet potato in the Biofortification Challenge Program of the cgiar (CGIAR, 2002).
Various agronomic measures can improve the nutritive value of some food crops. Application of zinc to the soil increases grain zinc content in cereal crops by a factor of two to three, depending on species and crop genotype. Application of zinc and phosphorus led to increased yield and also increased the amino acids methionine and lysine in wheat grains in Bangladesh (Graham et al.,1999).
Medicinal plants are emerging as medical aids for health maintenance all over the world. The global market for medicinal plants is expected to grow considerably in the coming decade. Europe accounts for the largest part of this market. So conservation and propagation of medicinal plants in farms and parks is required. Besides the impact on local health care and nutrition, cash crops of pharmaceutical and nutriceutical plants can have a positive impact on creation of jobs and local capacity building, such as it has happened in Brazil, Morocco and South Africa.