The Medical Significance of Cyanogen in Plant Foodstuffs

Abstract

Several plant foodstuffs in common use, particularly in the tropics, contain cyanide, either in the form of glycosides or nitriles. Acute poisoning can occur, especially in conditions of economic stress, and there are cogent reasons for continuing to control the cyanide content of cultivated lima beans, and to take precautions in the preparation of yams and cassava. Chronic ill effects from cyanogenetic glycosides have not been demonstrated in man, but serious liver disease has been induced experimentally by glycosides of cycads, and these plants have also been incriminated in hindquarter paralysis in livestock. Similarly, nitrile compounds with potent neurotoxic properties have been isolated from Lathyrus and Vicia seeds, but their relevance in human neurolathyrism has not been established. Although there is little doubt that hydroxocobalamin plays a part in the detoxication of cyanide, suggestions that cobalamin deficiency and ingested cyanide may be related factors in the pathogenesis of tropical neurologic or ophthalmic disorders remain only plausible theories. For a more complete understanding of this subject, more work is needed in fields which involve the biochemist, agriculturalist and veterinary surgeon as well as the epidemiologist and clinician. Such work is desirable in view of the increasing development of pulses as a source of dietary proteins.