Decreasing variety of plant foods used in developing countries

Abstract

During this century the science of nutrition has rapidly expanded and knowledge of nutrients in food and human requirements has greatly increased. This research has tended to concentrate on isolated nutrients and foods and has given the erroneous impression that the provision of a nutritious diet is a simple matter of adjusting intake of known nutrients to meet needs. Mankind does not eat foods in isolation but in mixtures which have evolved in each region over centuries—blended for desirable tastes, textures and colours. They contain hundreds of nutrients and other compounds which interact and cause changes in absorption and action. Furthermore, requirements vary for each individual and for many nutrients, particularly the trace elements, they are unknown. The maxim, ‘Safety in Numbers’, therefore also applies in the field of nutrition. Choice is limited by factors such as climate, eating patterns and shortage of food or purchasing power and the greater the variety of food that can be eaten within these constrictions—the greater the chance of a well-balanced diet. This great variety of foods ensured the survival of our huntergatherer ancestors but the number of foods has steadily declined with each stage of man's subsequent development. The advent of agriculture brought concentration on a few ‘staple’ crops providing most of the energy and protein requirements but deficient in some of the known essential vitamins and minerals. However, these foods alone were monotonous and unpalatable and so they were eaten with sauces and relishes containing a variety of food, mostly gathered wild, rich in the nutrients deficient in the staple. Mankind, therefore, in satisfying, his appetite, ensured his nutritional needs and the consequent expansion of population brought problems of deprivation. Conditions of proverty restrict both quantity and variety of food. Hunter gatherers used several thousands of different foods and the decline began with shifting cultivation. Settled agriculture increased pressure on the land with receding areas for the collection of wild plants and animals and wood for fuel. Urban development and market economies further concentrated production on a few high yielding marketable varieties. Some species and varieties are being lost completely—depleting the genetic stock and our knowledge of the use of these plants. There is urgent need for research and conservation.