The main component in an African diet is carbohydrates derived from maize, sorghum, barley, millet, rice, starchy roots or tubers, usually eaten with meat, fish or leafy green vegetables.
Many of the protein foods like meat, fish, milk or eggs are relatively expensive, forcing many poor people to opt for the leafy green vegetables that are eaten with the carbohydrate starchy foods. The nutritive quality of the leaves, especially the protein content, has helped to avoid widespread levels of malnutrition in African societies. Apart from nutritional benefits, other resources can be obtained from green leafy vegetables. The African community is aware of the nutritive quality of leaves in addition to medicinal benefits of many plant varieties, making food and medicine intertwined in a complex relationship.
The protein content in leaves is said to be as high as that found in soybeans or milk. In some African communities, extracting the nutritive matter from leaves is a practice that has exploited leaves with non-digestible plant matter. Leaves from vines of bean varieties are pounded to a fine mash, squeezing out the liquid and discarding the solids. The liquid extract is used to make nutritive food suitable for nursing mothers. This practice may have been the basis of the knowledge for extraction of proteins from leaves to make leaf concentrates. Leaf Protein Concentrate (LPC) is prepared by grinding young leaves to a pulp, pressing the paste, then isolating a liquid fraction containing protein. It is a nutritive product that could have significance in combating malnutrition.
Exploiting chemicals in leaves:
There are strong chemicals in leaves. Some are toxic, but others have found use as medicines. The indigenous people of Africa have good and accurate knowledge of the presence of toxins or useful chemicals in leaves and their application. Some leaves, like those of cassava, contain toxic cyanogenic substances. For assured detoxification, cassava leaves are pounded to a mash or cut to fine small slices washed and thoroughly boiled as part of food preparation. In the coca plant, the leaves are chewed to reduce hunger pains and leaf stems of plants of the cactus have complex chemicals that have steroidal or hallucinogenic effects that have been illicitly exploited. Chemicals with medicinal properties to treat stomach ulcers, for use as laxatives and antiseptics are well known from the aloe species, while other plants are a source of plant protein-sweeteners and soap derivatives. A recent commercial benefit from a leaf is demonstrated by the Aloe Vera species.
