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Summary Dietary cyanide exposure from cyanogenic glucosides in insufficiently processed cassava has been advanced as a contributing factor in child growth retardation. Whether cyanide exposure aggravates children's growth retardation was studied by comparing two populations of children from the northern and the southern zones of the Bandundu region, Democratic Republic of Congo (former Zaire), using dietary interviews, anthropometry and urine analyses. Both populations consumed cassava as their staple diet, but whereas in the north the cassava was well processed, in the south it was inadequately processed. The mean urinary thiocyanate was much higher in the south, whereas mean urinary sulphate excretion was equally low in the two areas. However, the mean urinary SCN/SO^sub 4^ molar ratio was higher in the south (0.20), indicating that 10-20% of sulphur amino-acids were used for cyanide detoxication. No significant differences were found between the two populations in weight-for-height and weight-for-age indices but the height-for-age index was significantly lower in children from the south, indicating more severe growth retardation in children exposed to dietary cyanide. Because of the preferential use of sulphur amino-acids for cyanide detoxification in the human body, dietary cyanide exposure from cassava may be a factor aggravating growth retardation in Bandundu.
Introduction
Anthropometry is used widely to assess malnutrition in children in developing countries. The three main indices are derived by comparing height and weight measurements with those of children in a reference population. Standard deviation scores (Z scores) are calculated for height-for-age (HFA), weightfor-age (WFA) and weight-for-height (WFH). Deficit in one or more of the indices is regarded as evidence of malnutrition.1 Although several factors can cause malnutrition, repeated infection and inadequate diet are the main causes in developing countries.2-4
In the 1960s, it was suggested that cassava might aggravate malnutrition in children owing to its low protein content and the low energy density of food products prepared from cassava roots 5 In recent decades, by virtue of its high yields and drought tolerance, cassava (Manihot esculenta) has become an increasingly important staple in the tropics, especially in sub-Saharan Africa. It provides better food security than most other staple crops.6 However, if cassava is to have an optimal health effect, its low protein content and low energy density must be compensated for by protein--...