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

Hi Elise - you question raises an interesting issue. Getting guidance on your question my guess is that you might receive confusing mixed and conflicting signals from experts in the field. In our view - the cause for part of the confusion around nutritional outcomes is that too many conclusions are based on clinical investigations that have not taken into account the form of the nutrients used. Where nutritional research that has been conducted that does not even mention the nutritional form used means that the investigators have not understood the important issue of form. Nutritional form has enourmous consequence for bio-availability and of course toxicity. Wherever I read nutritional research conclusions that do not mention the form of the nutritional supplimentation used - I put a large question mark on the outcome reported. Has anybody out there ever wondered why proposed daily RDA levels are set sometimes as high as 14 magnitudes higher that what the body requires on a daily basis. The reason is simply that those creating these RDA standards have based their understandings on nutrient forms that have little bio-availability to the body. Electrolytic iron, ferrous sulphate,,calcium carbonate and zinc oxide are good examples and where used in interventions show little benefit in terms of getting a human being back to nutrient repleteness. Sadly the commonly used BMI measurment used to measure malnourishment does not measure nutrient repleteness.. This commonly used standard used to measure success in addressing malnutrition can be achieved using just one or 2 macro nutrients. A victim may be measured as having their malnourishment adderssed using sterile food but might still remain completely dysfunctional and nutrient defecient. The condition is now refered to as the "hidden hunger" and is probably the reason why the Lancet talk about the Nutrition Industry as being fragmented dysfuntional and .in desperate need of reform.

See also: Schlesinger L, Arevalo M, Arredondo S, Lonnerdal B, Stekel A. Zinc supplementation impairs monocyte function. Acta Paediatr 1993 82:734-8. Abstract: Zinc has been shown to be involved in many functions of the immune system. This study was conducted to examine the effect of zinc supplementation on phagocytic, fungicidal and metabolic activity of blood monocytes of marasmic infants during nutritional rehabilitation. A controlled, double-blind design was used in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same, unfortified formula. Evaluation of phagocytic-fungicidal capacity, growth, zinc, copper and iron status was performed in both groups on admission and after 60 and 105 days of nutritional rehabilitation. Although energy, copper and iron intakes were similar in the two groups, a decrease in the number of infants able to phagocytose one or more Candida buds was observed after 60 days of zinc supplementation compared to admission (p < 0.03). No change in phagocytic ability was detected between admission and 60 days in the control group. The number of infants with depressed fungicidal activity increased significantly after 105 days of nutritional rehabilitation in the zinc-fortified group as compared to controls (p < 0.04). The number and duration of impetigo episodes was significantly greater in the group fed the zinc-fortified formula. These results suggest that zinc supplements at the RDA level may impair monocyte function Again the zinc supplements may have induced copper deficiency as the most likely reason for this fnding - in all the diets that I have designed for SAM there is adequate copper to prevent this interaction. cheers Mike

From Nina Berry: Hi All While I realise that this discussion is about the risks and benefits of zinc supplementation in children who have diarrhoeal illnesses, I would like to draw everyone's attention to a couple of issues that are raised by Schlesinger and colleagues' abstract. First they do not include a breastfed reference group and it is not clear why, since breastfeeding is both the biological norm and offers infants the best chance of survival beyond infancy. (It has already been noted that human milk contains zinc in a form that is without peer, in terms of bioavailability.) This implies that standard treatment of malnourished infants necessarily involves artificial feeding and completely neglects the role of breastfeeding in child survival. Second, their protocol does not appear to include support for breastfeeding mothers/carers and/or a relactation protocol for those mothers/carers who have already ceased breastfeeding children less than 2 years old. This is likely to result in poor long term outcomes, both in terms of infant mortality and in terms of the community's confidence in breastfeeding/mothers' milk. Too often mothers come to view the white powder as superior to breastfeeding (because they have seen their infants recover when it is used and no one pays any attention to breastfeeding) with disastrous results. Artificial feeding has a place, but it should be understood to be a last resort (due to the inherent risks both to individuals and communities). Furthermore, any treatment of infants/young children with SAM should include support for mothers/carers already breastfeeding and a relactation protocol for those who are not (including feeding the mothers if necessary). This will in turn require the recruitment of personnel trained in the assessment and management of breastfeeding and the training of community based breastfeeding counsellors. Otherwise, short term outcomes (discharge from SAM treatment programmes) will be overshadowed by subsequent mortality rates. Cheers Nina

Just a quick comment about breastfeeding and zinc levels. I completely agree with the need to focus on breastfeeding but need to keep in mind that Zinc is one of the substances in breastmilk that marketedly decreases. In fact many believe the first foods introduced to a 6 month old should be high in zinc due to low levels in the breastmilk at that time. So while important to continue to encourage breastfeeding if we are talking about the need for zinc after 6 months old it will need to be orally.