Zinc supplementation: effects on the growth and morbidity of undernourished Jamaican children

Abstract

Objective: We investigated whether there was a growth or morbidity response to zinc supplementation. Design: The study was randomized, placebo-controlled, and double-blind. Setting: Children were recruited at clinics in Kingston, Jamaica, and supplemented at home. Subjects: Children selected were singletons aged 6±24 months, and stunted (`À2.0 s.d. length for age, NCHS references). They were strati®ed by sex and age and randomly assigned to receive zinc supplement (n 31) or placebo (n 30). Four children were excluded because of hospitalization; all others had all measurements. Adequately nourished children (n 24) were recruited from a well-baby clinic. Interventions: The supplement provided 5 mg elemental zinc in a syrup daily for 12 weeks; the placebo comprised the syrup only. Main outcome measures: Caretakers were interviewed to obtain social background data, number of clinic visits and hospitalizations. Anthropometric measurements were done on enrolment, and after 6 weeks, 12 weeks and 12 months. Children's health was determined by weekly questionnaire to caretakers of the undernourished groups during the supplementation period. Results: The supplemented and placebo groups were similar on enrolment. The adequately nourished children were from signi®cantly better socio-economic circumstances. Mean initial hair zinc content was 5.5 AE 4.8 mmolag (supplemented group) and 6.7 AE 12.1 mmolag (placebo)(n.s.). Regression analyses showed that there were no signi®cant effects of supplementation on length, height or head circumference, nor on the incidence of any morbidity symptom. Mean duration of the episodes was signi®cantly shorter for skin rashes in the supplemented group compared with the control group (ANCOVA, P 0.02), and longer for vomiting (P 0.02). The incidence of hospitalization was signi®cantly greater in the control group (Fisher's exact test, P 0.02). Conclusions: Zinc supplementation reduced the hospitalizations which probably re¯ect severity of morbidity, but did not improve growth.

Zinc Supplementation Increases the Level of Serum Insulin-Like Growth Factor-I but Does Not Promote Growth in Infants with Nonorganic Failure to Thrive

“…Weight and height gains were also observed in these studies. In contrast, zinc supplementation had no effect on weight gain and only marginally improved height gain in stunted infants [23, 24]. The infants we studied were younger and we are unaware of any other reports on the effects of zinc supplementation on circulating IGF-I in this age group.…”

Beneficial effects of zinc supplementation on head circumference of Nepalese infants and toddlers: a randomized controlled trial

“…[29][30][31] The literature on randomized studies of zinc supplementation during pregnancy and head circumference at birth is also mixed with two studies reporting an association, 32,33 one showing an association only in children of mothers with body mass index of o26, 34 and four studies suggesting no association. [35][36][37][38] There has been one prospective study based on a food frequency questionnaire suggesting an inverse association between zinc intake of mothers in the second trimester of pregnancy with head circumference at birth. However, authors point out that results must be interpreted with caution as zinc could have been prescribed to prevent fetal growth retardation.…”

Zinc or Multiple Micronutrient Supplementation to Reduce Diarrhea and Respiratory Disease in South African Children: A Randomized Controlled Trial

“…Despite the food insecurity and poverty in the community, only 6.4% of children in this study were <2 z scores for length-for-age, compared to 32–100% of children in studies included in the meta-analysis of prophylactic zinc supplementation. A number of studies have shown the impact of zinc prophylaxis is greatest on those who are stunted or underweight,[7], [20], [21] or enrolled only those who were undernourished [22], [23][24], [25] Studies that have not found an effect on diarrheal or respiratory morbidity have often included better nourished children [26].…”