Cassava, cyanide and hypothyroidism

Abstract

Cassava (manioc) is an important crop as a basic, starchy energy food for both humans and farm animals throughout the tropics and sub-tropics and it is also exported to temperate regions, but does not seem to receive attention equivalent to that accorded to the other crops in this group. Its status as a good subsistence crop owes something to its self-protection by way of cyanogenic glycosides hydrolysed to release cyanide ions when tissue is damaged and the glycosides are thus placed into contact with an enzyme that hydrolyses them and is also present in the plant tissue. Cyanide toxicity and the toxin’s links, proven and possible, with goitre and hypothyroidism are described and their practical significance is discussed. The potential for responses to be changed by deficiencies in nutrients such as Vitamin B12, iodine and certain amino acids, as well as consumers’ overall nutrient status, is discussed. Suggestions are offered for future research to clarify significant issues presented from these considerations.