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Technical expert
21 Jul 2009, 10:26
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Zinc is of course vital. But as with all nutrients there is a U-shaped curve with the lower limb related to deficiency and the upper limb to toxicity. there has to be enough but not to much. There is plenty of zinc in RUTF/F100/F75 for rehabilitation of the severely malnourished child with diarrhoea - about 2mg/kg/d will come from these diets, with adequate copper to prevent zinc-induced copper deficiency. There IS a danger in these children of overdosing. See Doherty CP, Sarkar MA, Shakur MS, Ling SC, Elton RA, Cutting WA. Zinc and rehabilitation from severe protein-energy malnutrition: higher- dose regimens are associated with increased mortality. Am J Clin Nutr 1998 September;68(3):742-8. Abstract: A randomized, double-blind trial was undertaken to measure the effects of zinc supplementation on catch-up growth in severe protein-energy malnutrition, with particular reference to linear growth. One hundred forty-one children between the ages of 6 mo and 3 y were enrolled after admission to a nutritional rehabilitation unit in Dhaka, Bangladesh, and randomly assigned to receive elemental zinc by mouth, 1.5 mg/kg for 15 d, 6.0 mg/kg for 15 d, or 6.0 mg/kg for 30 d, and thereafter they were followed for a total of 90 d. Anthropometric outcome measures included change in knee-heel length, midupper arm circumference, subscapular and triceps skinfold thicknesses, and change in height-for- age, weight-for-age, and weight-for-height z scores. Higher zinc doses were not associated with significant change in any anthropometric measurement, but mortality was significantly greater in children who received high-dose zinc (6.0 mg/kg) initially as opposed to those who received low-dose zinc supplementation (1.5 mg/kg) (Yates-corrected chi- square P value of 0.033 and a risk ratio of 4.53; 95% CI: 1.09 < risk ratio < 18.8). We conclude that there is no benefit to using high-dose zinc supplementation regimens and that they could contribute to increased mortality in severely malnourished children This additional toxicity could well have been due to induced copper deficiency or some other cause - but it would be unwise to give full doses of zinc to the malnourished who are being treated with COMPLETE rehabilitation diets. cheers Mike Golden
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