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BACKGROUND: The role of single micronutrient deficiencies in the etiology of growth retardation has recently gained attention. However, because multiple micronutrient deficiencies are common in children in developing countries, it is possible that more than one micronutrient may limit growth and, hence, the correction of a single deficiency may not be enough to improve growth substantially. OBJECTIVE: The objective was to evaluate the effect of multiple micronutrient supplementation on the growth of children aged 8-14 mo whose diets were poor in several micronutrients. DESIGN: Children were randomly assigned to 1 of 2 groups. One group received a multiple micronutrient supplement containing the recommended dietary allowance (RDA) or 1.5 times the RDA of vitamins A, D, E, K, C, B-1, B-6, B-12, riboflavin, niacin, biotin, folic acid, and pantothenic acid, and iron, zinc, iodine, copper, manganese, and selenium. The other group received a placebo. Supplements were administered 6 d/wk for an average of 12.2 mo. Body length was measured at baseline and monthly thereafter until the end of supplementation. RESULTS: Supplemented infants initially aged <12 mo had significantly greater length gains than did the placebo group, with a difference of 8.2 mm (length-for-age z score: 0.3) at the end of supplementation. In contrast, differences in length gains between the supplemented and placebo groups initially aged > or =12 mo were not significant. CONCLUSIONS: Micronutrient deficiencies limited the growth of the Mexican infants studied. Improving micronutrient intakes should be a component of interventions to promote growth in infants living in settings where micronutrient intakes are inadequate.

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The adverse effects of lead have been known for long since the metal affects practically all organs and systems of the human body. Recently, toxic effects have been reported in the cardiovascular and nervous systems at lead levels previously considered to be secure. The main lead storage site in the body is bone. The toxicologic significance of this fact has been clarified only recently. The present study analyzes the role of lead as an endogenous source of exposure, as a chronic exposure biomarker and as a target organ. Recent advances to measure bone lead through fluorescent X-Rays are discussed. Additionally, the importance of bone lead from a public health perspective in places with a chronic history of exposure such as Mexico City, and in some occupational environments is reviewed with particular attention placed on reproductive age women, who are potential lead sources for the fetus and lactating infant.

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To evaluate whether milk production can be improved by increasing food intake, a randomized, double-blind, supplementation trial was completed among 102 lactating Guatemalan women. The subjects were undernourished, as indicated by their low values for calf circumference (CC) and the small size of their infants at birth. A high-energy (2.14 MJ/d, HES) and a low-energy (0.50 MJ/d, LES) supplement were distributed 6 d/wk from wk 5 to 25 of lactation. Data were evaluated using repeated-measures analysis of variance on the increments from initial values for each outcome variable with one-tailed tests of statistical significance. The maternal energy intake increased 1.18 MJ/d (P < 0.01) more among the HES than the LES women. Benefit from supplementation was more evident among the more undernourished (CC

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OBJECTIVE: To compare the capacity of two cut-off points of weight-for-age and length-for-age (-1 and -2 standard deviations) at different ages in the interval between birth and 30 months to predict stunting in three year old children. MATERIAL AND METHODS: Data from a longitudinal study in Guatemala were used to evaluate the hypothesis that the capacity of cut-off values of weight-for-age and length-for-age to predict stunting at three years of age varies according to age. RESULTS: Length-for-age at -1 standard deviation (SD) of the WHO/NCHS mean reference values is a satisfactory prognostic indicator of stunting at three years of age during the first semester of life, while the same index at -2 SD is adequate after 9 months of age. Weight-for-age at -1 SD is a suitable indicator only at 9 months and at -2 SD the indicator is satisfactory between 15 and 24 months of age. CONCLUSION: The capacity to predict stunting at three years of age, for weight-for-age and length-for-age cut-off values varies according to age.

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OBJECTIVE: To identify determinants of weight (BW) and length at birth (BL). MATERIAL AND METHODS: We studied 481 mother-newborn pairs in three Mexico City hospitals. Multiple regression models were developed to identify statistically significant predictors of BW and BL with respect to a predetermined biological model. Independent variables included were: maternal anthropometry, age, smoking habits, and civil status, parental education, obstetric history, hypertension, and neonatal characteristics. RESULTS: In the group with calf circumference (CC), height and head circumference below the median BW was 133, 92 and 96 g lower (+/- 35 standard error -SE-, p < 0.01) than the group above the median, adjusting for socioeconomic, obstetric history, and neonatal characteristics (NC). In the group below the median CC or height, BL was 5.8 or 6.2 mm (+/- 1.9 mm SE, p < 0.01) respectively, adjusting for obstetric history and NC. CONCLUSIONS: Results suggest that maternal anthropometry is the most important predictor of birth size and that predictors for BW and BL differ.

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Despite the recent declines in environmental lead exposure in the United States and Mexico, the potential for delayed toxicity from bone lead stores remains a significant public health concern. Some evidence indicates that mobilization of lead from bone may be markedly enhanced during the increased bone turnover of pregnancy and lactation, resulting in lead exposure to the fetus and the breast-fed infant. We conducted a cross-sectional investigation of the interrelationships between environmental, dietary, and lifestyle histories, blood lead levels, and bone lead levels among 98 recently postpartum women living in Mexico City. Lead levels in the patella (representing trabecular bone) and tibia (representing cortical bone) were measured by K X-ray fluorescence (KXRF). Multivariate linear regression models showed that significant predictors of higher blood lead included a history of preparing or storing food in lead-glazed ceramic ware, lower milk consumption, and higher levels of lead in patella bone. A 34 micrograms/g increase in patella lead (from the medians of the lowest to the highest quartiles) was associated with an increase in blood lead of 2.4 micrograms/dl. Given the measurement error associated with KXRF and the extrapolation of lead burden from a single bone site, this contribution probably represents an underestimate of the influence of trabecular bone on blood lead. Significant predictors of bone lead in multivariate models included years living in Mexico City, lower consumption of high calcium content foods, and nonuse of calcium supplements for the patella and years living in Mexico City, older age, and lower calcium intake for tibia bone. Low consumption of milk and cheese, as compared to the highest consumption category (every day), was associated with an increase in tibia bone lead of 9.7 micrograms Pb/g bone mineral. The findings of this cross-sectional study suggest that patella bone is a significant contributor to blood lead during lactation and that consumption of high calcium content foods may protect against the accumulation of lead in bone.

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Iron deficiency is one of the most prevalent forms of malnutrition which is clinically known as anemia. Functional consequences of anemia include impairment of cardiovascular performance, limitation in productivity, higher incidence of low birth weight and premature delivery, and increased maternal mortality. This paper presents a descriptive analysis of anemia in women of reproductive age in Mexico. Data were collected by the Ministry of Health through a National Nutrition Survey in 1988, which draw a representative sample from four regions: North, Center, South and Federal District. Anemia was more prevalent in pregnant (18.17%) than in non-pregnant women (15.38%). Those women living in predominantly indigenous communities had higher prevalence of anemia (24.02%) than non-indigenous women (14.67%). Anemia was more prevalent in urban areas (15.54%) than in rural (13.56%). Mean +/- standard deviation values for hemoglobin were lower in pregnant women (12.5 +/- 1.6 g/dL) than in non-pregnant ones (13.7 +/- 1.6 g/dL). Consistently, the Northern and Southern regions were worse off than the Center and the Federal District. These data indicate that anemia is a public health problem in Mexico. The functional consequences of this deficiency justify interventions to treat and prevent it.

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Data from a National Nutrition Survey conducted in 1988 in a probability sample of 13,236 households and 17,426 children under five, representative at the national level and for four regions (North, Center, South, and Mexico City), were analyzed. Risks for wasting and stunting and odds ratios were obtained by region, by district according to proportion of indigenous population and by level of urbanization, by level of education of both parents, by gender, and by various combinations of the former strata. A high risk of stunting and a low risk of wasting were found. The risk of stunting is greater in predominantly indigenous and rural districts, in the South and Center, and in families of mothers with low education and poor housing conditions. The results can be used for food and nutrition policy planning and for targeting nutrition intervention programs.

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The level and avidity indices of specific antibodies against tetanus toxoid, Escherichia coli O6 and a pool of 10 common E. coli O antigens, as well as the concentration and daily output of lactoferrin and total secretory IgA (SIgA), were evaluated in the milk of moderately undernourished mothers who were in a random blind design divided into two groups and given different caloric supplementations. Group A received a high caloric supplement (500 kcal/d), and group B received a low caloric supplement (140 kcal/d). Determinations were done using ELISA in various modifications, except for lactoferrin, which was quantified by single radial immunodiffusion. The avidity indices were investigated as an evaluation of the antibody quality. In all the parameters evaluated, the only difference found between the two groups at the end of the supplementation period was in the content of total SIgA, which was lower in group B, both in concentration and daily output. However, the SIgA remained within the normal range. Increases as well as decreases in the levels of specific IgA antibodies occurred within both groups. Avidity was decreased in group B only against one of the antigens tested. We conclude that moderate undernutrition does not impair the levels of milk antibodies, and supplementation does not enhance them but prevents the decrease in the content of total milk SIgA. There is a suggestion that the avidity of certain antibody specificities could be hampered.

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