Factors affecting the limitation of the cultivation of grain legumes in tropical territories.

Plant breeding and nutrition 57 Favism is a disease characterized by haemolytic anaemia that affects certain individuals following the ingestion of the broad or field bean, Viciafaba. In spite of rather extensive studies that have been made regarding the clinical and biochemical manifestations of favism, the causative principle of favism has not been identified with any degree of certainty. Recent evidence would suggest, however, that perhaps vicine, a nucleoside composed of glucose and 2,s -diamino-+~-diketopyrimidine, may be responsible for favism, at least in persons genetically susceptible to this disease. There exists a fairly large category of natural substances that interfere with the utilization of certain minerals and vitamins. As examples, isolated soya-bean protein has been shown to interfere with the availability of such minerals as zinc, manganese, copper and iron as well as vitamin D; raw kidney beans contain a factor that increases the vitamin E requirements of the chick; and linseed meal contains an antagonist of pyridoxine. Only the latter has been identified and has been shown to be 1-amino-o-proline. The significance of naturally-occurring toxicants in human nutrition is still largely unknown, and they may not in fact pose much of a problem as long as man is able to select a varied diet. But there is the possibility that the prolongcd consumption of any one foodstuff may bring to the surface toxic effects that have not heretofore been apparent. I t is this sort of occurrence that may be expected to become more commonplace as the shortage of protein becomes more acute, and certain segments of the population are forced to become less discriminating in their choice of lifesustaining foods. By selecting those strains and varieties of plants that are genetically deficient in components of possible toxicity to man, the co-operative efforts of the nutritionist and plant breeder can do much to forestall this problem.