ABSTRACT
BACKGROUND: The efficacy of micronutrient supplementation on growth may be modified by specific gastrointestinal parasite infections. METHODS: We carried out a double-blind placebo-controlled trial to evaluate the effect of vitamin A and zinc supplementation on gastro-intestinal pathogen infections and growth among 584 infants in Mexico City. Children aged 5-15 months were assigned to receive either a vitamin A supplement every 2 months (20,000 IU of retinol for infants < or =; 1 year or 45,000 IU for infants >1 year), a daily supplement of 20 mg of zinc, a combined vitamin A-zinc supplement or a placebo, and were followed up for 1 year. Weight and length were measured once a month and morbidity histories were recorded twice a week for 12 months. Monthly stool samples were screened for Giardia duodenalis, Ascaris lumbricoides and Entamoeba spp. Growth velocity slopes, generated from the linear regression of individual child length, and height-for-age z-scores on time were analyzed as end points in regression models, adjusting for the presence of parasite infections. RESULTS: The main effect of vitamin A supplementation was in height improvement (P<0.05), and was only found in the model evaluating infants with any parasite. There was an interaction effect of slower growth (P<0.05) found in infants infected with any parasite and supplemented with vitamin A in slower growth (P<0.05). In addition, the interaction of zinc supplementation and Giardia duodenalis or A. lumbricoides was associated with reduced growth (P<0.05). CONCLUSION: Gastro-intestinal parasite infections may modify the effect that zinc or vitamin A supplementation has on childhood growth.
Subject(s)
Body Height/drug effects , Body Weight/drug effects , Growth/drug effects , Intestinal Diseases, Parasitic/complications , Vitamin A/pharmacology , Zinc/pharmacology , Animals , Ascariasis/complications , Ascaris lumbricoides , Body Height/physiology , Body Weight/physiology , Dietary Supplements , Dysentery, Amebic/complications , Feces/parasitology , Female , Giardiasis/complications , Growth/physiology , Growth Disorders/etiology , Growth Disorders/prevention & control , Humans , Infant , Male , Mexico , Trace Elements/pharmacology , Vitamins/pharmacologyABSTRACT
The validity of 7 d weighed records of diet obtained for pre-menopausal Mexican women was assessed by two independent methods: the energy intake:BMR (EI:BMR) and the dietary N:urinary N (DN:UN). For the latter, complete urine collections are required and completeness was assessed from measurements of para-aminobenzoic acid (PABA) excretion. There were forty-six adult female subjects in the study, thirty-four were from Mexico City and twelve were from a rural population in the Central Highlands, Mexico. However, data were rejected from five urban women for whom the PABA excretion data suggested incomplete urine collection on four or more days. BMR was measured with Oxylog portable O2 consumption meters, and physical activity level was assessed from a self-completed activity diary. An approximate relationship between the EI:BMR ratio and the DN:UN ratio suggested that the rejection limits on the EI:BMR ratio recommended by are wider than the limits on the DN:UN ratio recommended by. Using the recommended cut-off points for EI:BMR but wider limits for DN:UN, twenty-one and twenty-five women respectively had acceptable intake records by the two methods, and sixteen of them by both methods. In conclusion the modification of the DN:UN limits to 0.92 and 1.70 to set acceptable intake values makes the use of measurements of N and energy balance comparable. Urine values with PABA recoveries greater than should be rejected, as should UN values validated by less than 3 d.
