Kamalu B P
Department of Veterinary Pathology and Microbiology, University of Nigeria, Nsukka.
Int J Food Sci Nutr. 1995 Feb;46(1):65-93. doi: 10.3109/09637489509003387.
Cassava (Manihot esculenta Crantz) is an important dietary staple for more than 500 million people in developing countries. People eat 60% of the cassava produced and one third of the harvest feeds animals. All cultivars of cassava contain the cyanogenic glucoside, linamarin, but in different concentrations. The roots of those cultivars with high cyanogenic content are processed to reduce the level of linamarin, because linamarin is hydrolysed in the intestinal tract of both men and animals by microbial flora and HCN is released. Researchers have implicated the sublethal levels of HCN produced on ingestion in the development of a number of metabolic diseases in both man and animals when cassava-based diets are consumed over a long period of time but the release of HCN cannot fully explain the metabolic effects of ingested linamarin. A significant amount of linamarin remains intact and is excreted in the urine. It appears that the intact linamarin inhibits Na+K+ATPase causing electrolyte imbalance within the cell. This phenomenon is exacerbated by free radicals generated by the hypoxia/normoxia cycles created by cyanide released from linamarin, which cause lipid peroxidation and cell membrane damage. When the supply of endogenous thiosulphate is adequate, cyanide plays a very minor role in the development of lesions. The amount of damage is related to the quantity of linamarin routinely ingested at sublethal levels. There appears to be species differences in the rate of the development of diseases and the intensity.
木薯（Manihot esculenta Crantz）是发展中国家5亿多人重要的主食。人们食用了所生产木薯的60%，三分之一的收成用作动物饲料。所有木薯品种都含有氰苷亚麻苦苷，但含量不同。那些氰化物含量高的品种的根经过加工以降低亚麻苦苷的含量，因为亚麻苦苷在人和动物的肠道中会被微生物菌群水解并释放出HCN。研究人员认为，长期食用以木薯为主的饮食时，摄入的HCN亚致死水平会导致人和动物出现多种代谢疾病，但HCN的释放并不能完全解释摄入的亚麻苦苷的代谢作用。大量的亚麻苦苷保持完整并随尿液排出。完整的亚麻苦苷似乎会抑制Na+K+ATP酶，导致细胞内电解质失衡。亚麻苦苷释放出的氰化物产生的缺氧/常氧循环所生成的自由基会加剧这种现象，自由基会导致脂质过氧化和细胞膜损伤。当内源性硫代硫酸盐供应充足时，氰化物在病变发展中起的作用很小。损伤程度与亚致死水平下常规摄入的亚麻苦苷量有关。疾病发展的速度和强度似乎存在物种差异。
