Philip A. Walravens

FAILURE TO THRIVE AND ZINC DEPLETION IN BREAST-FED INFANTS: COMPLICATIONS OF UNPLANNED PREGNANCY IN NURSING MOTHERS

In a study of failure to thrive, 3 infants with a similar pattern of growth deviation were encountered. Weight gain ceased at 6 months in two and at 8 months in the 3rd. Breast milk was the main source of calories for all infants and refusal of milk supplements and lack of interest in solids was reported. Dietary analysis for a 6 month girl showed an average intake of 580 ml breast milk and 100 kcal daily from solids. The zinc content of breast milk was in the normal range (0.49 - 0.64 mg/l) for the stage of lactation. Total daily zinc intake approximated only 0.9 mg however, or 18% of the RDA. In a 9 month male, dietary intake consisted of frequent short bouts of nursing and 280 kcal from solids. In this infant, anorexia and poor weight gain persisted for 6 additional months until zinc supplements were provided and catch-up growth occurred. Low plasma zinc levels (57 & 67 μg/dl) were found when assayed in two of the infants. Retrospectively it was realized that the mothers became pregnant at the time the growth failure began in the infants. Unexpected pregnancy should be considered if breast-fed infants show an unexplained failure to gain weight. Zinc may furthermore cause anorexia and delay catch-up growth until supplements are provided to correct the depletion.

657 ZINC SUPPLEMENTATION OF LOW INCOME PRESCHOOL CHILDREN: EFFECT ON GROWTH

Many preschool children from low-income, Mexican-American families have low growth percentiles. Biochemical evidence for inadequate Zn nutrition was found in a group of such children in Denver. The effects of Zn supplementation on growth velocity and indices of Zn nutrition were examined in a double-blind pair-matched controlled study.Children, 3-6 years of age, were screened, with parental consent if height and weight were at or below the 10th percentile. Inclusion in the study required an additional 2 of the following: hair Zn <100 μg/g, plasma Zn <68 μg/dl, urine Zn <100 μg/24hrs or dietary Zn intake <2/3 of RDA (i.e. <6mg/day). Participating children were assigned to take daily for 1 year either 10 mg of Zn as the sulfate in cherry syrup or a placebo syrup. Growth velocities were calculated from measurements obtained quarterly.Mean weight gains of the test and control children were 2.33 ± 1.22 and 1.69 ± 0.65 kg/yr respectively (p<0.10). Dietary intakes increased in the test group. This study shows a beneficial effect of Zn supplementation in a population where marginal Zn deficiency may affect appetite and growth velocity.

404 ZINC-BINDING LIGANDS IN DUODENAL JUICE AND SALIVA FROM NORMAL ADULTS AND ACRODERMATITIS ENTEROPATHICA PATIENTS

Acrodermatitis enteropathica (AE) is an autosomal, recessively inherited disease, the pathogenesis of which is attributable to severe zinc deficiency. Before the introduction of oral Zn therapy some AE patients were treated effectively with breast milk. A zinc-binding ligand (ZBL) which may facilitate the absorption of Zn has been found in human milk (but not cows milk) and in rat small intestine (Hurley et al., Proc. Nat. Acad. Sci., 1977). A similar ZBL may be present in human duodenal juice and an absence or defect in such a ligand could be one site of the molecular defect in AE. Samples of duodenal juice and mixed saliva from normal subjects were fractionated by gel chromatography on Bio-gel P-10. Most of the Zn eluted from the column in two peaks, one at the void volume and one at lower molecular weight. The second peak was further purified by electrophoresis on acrylamide gel and found to contain a ZBL similar in size to that in breast milk. Pancreatic juice and saliva from 3 AE patients also contained the ZBL. It is concluded that the ZBL is present in some cases of AE but it is not yet known if it is normal in quantity or quality. (Supported in part by NIH Postdoctoral Fellowship no. HD-07096 and USPHS Grant no. ROl-AM-12432.)