Effect of prenatal multiple micronutrient supplements on maternal weight and skinfold changes: a randomized double-blind clinical trial in Mexico.

BACKGROUND: Recent trials of prenatal multivitamin-mineral supplements have yielded mixed findings for outcomes such as birth size, but the benefits of prenatal multivitamin-mineral supplements for maternal outcomes are unknown. OBJECTIVE: The main objective of this study was to examine the effect of prenatal multiple micronutrient supplements (MM) compared to iron only (FE) supplements on changes in maternal weight and body composition during pregnancy and the early postpartum period. METHODS: A randomized double-blind clinical trial was conducted in semi-rural Mexico. Women received either MM or FE supplements, 6 days per week from early pregnancy to delivery. Anthropometric measurements were obtained at recruitment, 26 and 37 weeks pregnancy, and 1 month postpartum. Women in both groups were similar at recruitment except that body-mass index (BMI) was greater in the FE group. RESULTS: Mean weight gain during pregnancy was significantly greater (-0.6 kg) in the MM group (n = 283) compared to the FE group (n = 287), but not after adjusting for maternal BMI at recruitment. Overweight women in the MM group gained 0.53 kg between recruitment and 1 month postpartum, whereas those in the FE group lost 0.63 kg; there were no differences between experimental groups among non-overweight women (p =.06 for interaction). CONCLUSIONS: Compared to iron supplements, MM supplements did not increase weight gain during pregnancy after adjusting for baseline differences in BMI but may lead to greater postpartum weight retention among overweight women.

Multiple micronutrient supplementation during pregnancy does not lead to greater infant birth size than does iron-only supplementation: a randomized controlled trial in a semirural community in Mexico.

BACKGROUND: Little is known about the benefits of prenatal multivitamin and mineral supplements in reducing low birth weight. OBJECTIVE: We conducted a randomized, double-blind clinical trial in semirural Mexico to compare the effects of multiple micronutrient (MM) supplements with those of iron supplements during pregnancy on birth size. DESIGN: Pregnant women (n = 873) were recruited before 13 wk of gestation and received supplements 6 d/wk at home, as well as routine antenatal care, until delivery. Both supplements contained 60 mg Fe, but the MM group also received 1-1.5 times the recommended dietary allowances of several micronutrients. RESULTS: At recruitment, the women in the 2 groups were not significantly different in age, parity, economic status, height, or hemoglobin concentration but differed significantly in marital status (4.6% and 2.0% of women in the MM and iron-only groups, respectively, were single mothers) and mean (+/- SD) body mass index (in kg/m(2); 24.6 +/- 4.3 and 23.8 +/- 3.9 in the iron-only and MM groups, respectively). Losses to follow-up (25%) and compliance (95%) did not differ significantly between the groups. In intent-to-treat analyses (MM group: n = 323; iron-only group: n = 322), mean (+/- SD) birth weight (2.981 +/- 0.391 and 2.977 +/- 0.393 kg in the MM and iron-only groups, respectively) and birth length (48.61 +/- 1.82 and 48.66 +/- 1.83 cm in the MM and iron-only groups, respectively) did not differ significantly between the groups. CONCLUSION: These findings suggest that MM supplementation during pregnancy does not lead to greater infant birth size than does iron-only supplementation.

Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one month postpartum.

Despite the many well-recognized benefits of breast-feeding for both mothers and infants, detectable levels of lead in breast milk have been documented in population studies of women with no current environmental or occupational exposures. Mobilization of maternal bone lead stores has been suggested as a potential endogenous source of lead in breast milk. We measured lead in breast milk to quantify the relation between maternal blood and bone lead levels and breast-feeding status (exclusive vs. partial) among 310 lactating women in Mexico City, Mexico, at 1 month postpartum. Umbilical cord and maternal blood samples were collected at delivery. Maternal breast milk, blood, and bone lead levels were obtained at 1 month postpartum. Levels of lead in breast milk ranged from 0.21 to 8.02 microg/L (ppb), with a geometric mean (GM) of 1.1 microg/L; blood lead ranged from 1.8 to 29.9 microg/dL (GM = 8.4 microg/dL); bone lead ranged from < 1 to 67.2 microg/g bone mineral (patella) and from < 1 to 76.6 microg/g bone mineral (tibia) at 1 month postpartum. Breast milk lead was significantly correlated with umbilical cord lead [Spearman correlation coefficient (rS) = 0.36, p < 0.0001] and maternal blood lead (rS= 0.38, p < 0.0001) at delivery and with maternal blood lead (rS = 0.42, p < 0.0001) and patella lead (rS= 0.15, p < 0.01) at 1 month postpartum. Mother's age, years living in Mexico City, and use of lead-glazed ceramics, all predictive of cumulative lead exposure, were not significant predictors of breast milk lead levels. Adjusting for parity, daily dietary calcium intake (milligrams), infant weight change (grams), and breast-feeding status (exclusive or partial lactation), the estimated effect of an interquartile range (IQR) increase in blood lead (5.0 microg/dL) was associated with a 33% increase in breast milk lead [95% confidence interval (CI), 24 to 43%], whereas an IQR increase in patella lead (20 microg/g) was associated with a 14% increase in breast milk lead (95% CI, 5 to 25%). An IQR increase in tibia lead (12.0 microg/g) was associated with a 5% increase in breast milk lead (95% CI, -3% to 14%). Our results indicate that even among a population of women with relatively high lifetime exposure to lead, levels of lead in breast milk are low, influenced both by current lead exposure and by redistribution of bone lead accumulated from past environmental exposures.

Nutrition transition in Mexico and in other Latin American countries.

Mexico and other Latin American countries are currently undergoing important demographic, epidemiologic and nutrition transitions. Noncommunicable chronic diseases such as obesity, type 2 diabetes mellitus, and high blood pressure are becoming public health problems as the population experiences an important reduction in physical activity and an increase in energy-dense diets. In contrast, the prevalence of undernutrition is declining in most countries, although several decades will be needed before the prevalence drops to acceptable values. The objective of this article is to discuss the characteristics of the nutrition transition with emphasis in data from Mexico, Brazil, and Chile.

Body composition estimates using different measurement techniques in a sample of highland subsistence farmers in Guatemala.

This study aims at assessing the accuracy of estimates of body composition provided by bioimpedance (BIA) equations developed for U.S. populations when applied to a sample of Guatemalan farmers. If these equations were shown to have low validity, the second objective was to develop more accurate estimates of fat-free mass (FFM). One hundred males and females 19 to 45 years of age were randomly selected from four rural communities in the Western Highlands of Guatemala. Bioimpedance equations explained 59 and 33% of the variation in FFM, with a RMSE of 2.7 and 2.8 kg in males and females, respectively. Body fat (BF) predictions had a lower R2 . Using the "all possible regressions" procedure, the best subset for prediction of FFM used anthropometric and BIA variables as predictors. The best model for men and women included only anthropometric variables: 75% of the variance in FFM for men and 70% of the variance in women was explained by this model. The RMSE was 2.1 and 1.9 kg for both groups, respectively. It is concluded that FFM can be estimated from anthropometric dimensions with a high degree of accuracy and use of BIA does not provide more valid estimates.

Effect of maternal bone lead on length and head circumference of newborns and 1-month-old infants.

The authors evaluated the effects that maternal bone lead stores have in anthropometry at birth in 223 mother-infant pairs. The participants were recruited between April and November 1994. Anthropometric data were collected within the first 12 hr following delivery. Maternal information was obtained 1 mo after delivery occurred. Bone lead burden was determined with in-vivo K-x-ray fluorescence of the tibia (cortical bone) and the patella (trabecular bone). The authors transformed anthropometric measurements to an ordinal 5-category scale, and the association of measurements with other factors was evaluated with ordinal logistic-regression models. Mean bone lead levels were 9.8 microgram/gm bone mineral and 14.4 microgram/gm bone mineral for the tibia and patella, respectively. Birth length of newborns decreased as tibia lead levels increased. Compared with women in the lower quintiles of the distribution of tibia lead, those in the upper quintile had a 79% increase in risk of having a lower birth length newborn (odds ratio = 1.79; 95% confidence interval = 1.10, 3.22). The authors adjusted by birth weight, and the effect was attenuated--but nonetheless significant. Patella lead was positively and significantly related to the risk of a low head circumference score; this score remained unaffected by inclusion of birth weight. The authors estimated the increased risk to be 1.02 per microgram lead/gm bone mineral (95% confidence interval = 1.01, 1.04 per microgram lead/gm bone mineral). Odds ratios did not vary substantially after the authors adjusted for birth weight and other important determinants of head circumference.

Multiple micronutrient supplementation and dietary energy intake in pregnant women.

OBJECTIVE: To compare dietary intake of women supplemented with multiple micronutrients (MM) or iron only during pregnancy. DESIGN: Randomized, double-blind, controlled community-based trial. SETTING: One semi-urban community in Central Mexico. SUBJECTS: Pregnant women identified before week 13 of pregnancy, willing to provide informed consent. INTERVENTIONS: Women were randomly assigned to receive daily supplementation with MM or iron only from recruitment until delivery. Supplements were delivered to the participants' home and compliance observed daily. Dietary intake was assessed by repeat 24-hr recall. Data were analyzed using non-parametric tests and multiple regression analysis to determine the impact of MM supplementation on dietary intake of energy and select micronutrients. RESULTS: During the third trimester, women in the MM group consumed more energy and iron from dietary sources than women in the iron only group. After adjustment for differences between the groups at baseline, women in the MM group consumed 111.3 kcal/day more (p<0.05) energy. The difference in iron intake was not significant after adjusting for the increase in energy intake. CONCLUSIONS: Women consuming MM supplements during pregnancy increased energy intake from dietary sources without a concurrent increase in micronutrient density. Future studies should include measures of appetite and physical activity during pregnancy to determine the implications of additional energy intake for weight gain and retention.

[Contribution of processed foods to the energy, macronutrient and fiber intakes of Mexican children aged 1 to 4 years]. / Alimentos industrializados en la dieta de los preescolares mexicanos.

OBJECTIVE: To classify the foods consumed by Mexican children 1-4 years in three food categories according to the preparation process and temporality: a) Processed Modern Foods (PMF), b) Processed Traditional Foods (PTF) and c) Non-Processed Foods. MATERIAL AND METHODS: Twenty-four-hour dietary recalls were collected from the National Nutrition Survey 1999 in children 1-4 years (n =1070). The contribution of each food category to the total energy, macronutrient and fiber intakes was analyzed. RESULTS: The contribution of PMF and PTF was as follows, respectively: Energy: 17%, 31%; total protein: 14%, 25%; non-animal protein: 10%, 10%; animal protein: 17%, 34%; carbohydrates: 18%, 26%; fiber: 4%, 5%; total fat 15%, 41%; saturated fat 16%, 52%; and cholesterol 7%, 7%. CONCLUSIONS: The contribution of PF to the diets of Mexican children accounts for >39% of energy, total protein, animal protein, carbohydrates and fat. The authors recommend the participation of food industry to prevent malnutrition in children.

Poor compliance with appropriate feeding practices in children under 2 y in Mexico.

We evaluated breast-feeding and complementary feeding practices in Mexico, using data from a national probabilistic survey carried out in 17,716 households, with regional and urban-rural representation. Mothers of children <2 y old (n = 3,191) reported duration of breast-feeding and the ages of usual introduction of 7 food groups. The Kaplan-Meier method was used to estimate the median time of feeding events. Practices were analyzed by categories of ethnicity, housing condition, and place of residence (geographic region and degree of urbanization). We found that 86% of infants at 1 mo and 39% at 11 mo were breast-fed, whereas 60% at 1 mo and 8% at 6 mo were exclusively breast-fed. Early introduction (<6 mo) of water, nonhuman milk, nonnutritive liquids, and fruits and vegetables was reported for all categories studied. Also, early introduction of nutritive liquids, cereals and legumes, and animal foods other than milk occurred in all categories except rural areas and the indigenous population. Late introduction of solid foods was documented in large proportions of infants in rural areas and in poor families. Poorer, unemployed, and indigenous women, and those bearing males, had a significantly higher probability of feeding their infants as recommended by the WHO. Feeding practices were unrelated to attained growth when the influence of economic and social factors was considered. Results indicate the need to implement actions for the promotion of exclusive breast-feeding during the first 6 mo and of timely introduction of complementary foods thereafter.

The effect of micronutrient deficiencies on child growth: a review of results from community-based supplementation trials.

Several micronutrients are required for adequate growth among children. However, it has been unclear as to which nutrient deficiencies contribute most often to growth faltering in populations at risk for poor nutrition and poor growth. Therefore, evidence from community-based, randomized, placebo-controlled, micronutrient supplementation trials was reviewed to determine which micronutrient deficiencies have been found to be causal to growth faltering. Although correction of growth-limiting nutrient deficiencies may be achieved through provision of pharmacological nutrient supplements, it also was of interest to review evidence for the use of animal source food supplements to improved growth among children in at-risk populations. There is strong evidence for the contribution of zinc deficiency to growth faltering among children; even mild to moderate zinc deficiency may affect growth. Vitamin A and iron deficiencies also have been demonstrated to cause growth faltering, however only when the deficiency state of these nutrients is severe. Several controlled, community-based intervention trials that have included animal source foods, either together with additional micronutrient supplements or with other supplemental food sources, have demonstrated positive growth responses among children. Three trials that used an animal source food alone (skim milk powder) also resulted in a positive growth response. However, the geographic scope of the latter three trials was limited, and it remains unclear to what extent supplemental animal source foods alone and which types of animal source foods can be used to improve growth among children in at-risk populations.

Multiple micronutrient supplements during pregnancy do not reduce anemia or improve iron status compared to iron-only supplements in Semirural Mexico.

The impact of iron-only supplements (FE) versus multiple micronutrient supplements containing iron (MM) during pregnancy on iron status was assessed in a subsample (n = 453) of women who participated in a randomized double-blind trial in Mexico. Compliance, monitored by observation, was high (>85%). The two groups were similar at recruitment (<13 wk gestation) for various sociodemographic characteristics and for mean hemoglobin (Hb) concentrations and prevalence of anemia (Hb < 110 g/L; 11%). However, mean serum ferritin was higher (P < 0.05) in the MM group (n = 142) compared to the FE group (n = 148) and the prevalence of iron deficiency (serum ferritin < 12 micro g/L) was lower in the MM group (44.4%) compared to the FE group (57.4%). By the third trimester, almost half the women were anemic in both groups, and mean Hb (g/L) was lower for the MM group (104.2; 95% CI: 102.5, 106.0) compared to the FE group (108.1; 95% CI: 106.4, 109.8) after adjusting for baseline serum ferritin. In contrast, there were no differences in Hb concentrations at 1 mo postpartum or in mean ferritin and prevalence of iron deficiency at 32 wk gestation and 1 mo postpartum (90.9 and 45.1% for the MM group; 92.6 and 47.3% for the FE group, respectively). In conclusion, rather than improve Hb or iron status relative to FE-only supplements as hypothesized, MM supplements may have slightly reduced Hb concentrations during pregnancy. Neither supplement was able to meet iron needs as evidenced by dramatic increases in anemia and iron deficiency by the end of pregnancy.

Nutritional status of indigenous children younger than five years of age in Mexico: results of a national probabilistic survey.

OBJECTIVE: To compare the prevalence of undernutrition and anemia in indigenous and non-indigenous children < 5 years of age at the national level, by region and by urban and rural areas, and to evaluate the degree to which the socioeconomic condition of the family predicts the differences. MATERIAL AND METHODS: A national probabilistic survey was conducted in Mexico in 1999. Indigenous families were identified as those in which at least one woman 12-49 years of age in the household spoke a native language. The prevalence of undernutrition (stunting, wasting and underweight) and anemia was compared between indigenous and non-indigenous children. Probability ratios (PR) were used to compare prevalences in indigenous and non-indigenous children adjusting for socioeconomic status (SES) of the family and for other covariates. RESULTS: The prevalences of stunting and underweight were greater in indigenous than in non-indigenous children. At the national level and in urban areas the prevalences were three times greater and in rural areas approximately 2 times greater (p < 0.05). No differences were found in the prevalence of wasting (p > 0.05). The prevalence of anemia in indigenous children was one third greater than in non-indigenous children at the national level (p < 0.05) and was between 30 and 60% greater in urban areas and in the regions studied (p < 0.05) but was not statistically significant (p > 0.05) in rural areas. These differences were reduced to about half when adjusting for SES but remained significantly higher in indigenous children (p < 0.05). CONCLUSIONS: Indigenous children have higher probabilities of stunting and underweight than non-indigenous children. The differences are larger in urban areas and in higher socioeconomic geographic regions and are explained mostly by socioeconomic factors. The overall difference in the probability of anemia is small, is higher only in urban relative to rural areas, and is explained to a lesser degree by socioeconomic factors. Policy and programs should be designed and implemented to reduce the dramatic differences in nutritional status between indigenous and non-indigenous children in Mexico. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Dietary calcium supplements to lower blood lead levels in lactating women: a randomized placebo-controlled trial.

BACKGROUND: Pregnancy and breastfeeding mobilize lead stored in bone, which may be a hazard for the fetus and infant. We tested the hypothesis that in lactating women a dietary calcium supplement will lower blood lead levels. METHODS: Between 1994 and 1995 we conducted a randomized trial among women in Mexico City. Lactating women (N = 617; mean age = 24 years; mean blood lead level = 8.5 ug/dL) were randomly assigned to receive either calcium carbonate (1200 mg of elemental calcium daily) or placebo in a double-blind trial. Blood samples were obtained at baseline, and 3 and 6 months after the trial began. Blood lead was determined by graphite furnace atomic absorption spectroscopy. Bone lead was measured at baseline with a 109cd K x-ray fluorescence instrument. The primary endpoint was change in maternal blood lead level, which was analyzed in relation to supplement use and other covariates by multivariate generalized linear models for longitudinal observations. RESULTS: An intention-to-treat analysis showed that women randomized to the calcium supplements experienced a small decline in blood lead levels (overall reduction of 0.29 ug/dL; 95% confidence interval = -0.85 to 0.26). The effect was more apparent among women who were compliant with supplement use and had high bone lead levels (patella bone lead > or =5 microg/gm bone). Among this subgroup, supplement use was associated with an estimated reduction in mean blood lead of 1.16 ug/dL (95% confidence interval = -2.08 to -0.23), an overall reduction of 16.4%. CONCLUSIONS: Among lactating women with relatively high lead burden, calcium supplementation was associated with a modest reduction in blood lead levels.

Impact of breastfeeding on the mobilization of lead from bone.

To evaluate the hypothesis that lactation stimulates lead release from bone to blood, the authors analyzed breastfeeding patterns and bone lead concentrations as determinants of blood lead levels among 425 lactating women in Mexico City for 7 months after delivery (1994-1995). The authors measured in vivo patella and tibia lead concentrations at 1 month postpartum using K x-ray fluorescence. Maternal blood samples and questionnaire information were collected at delivery and at 1, 4, and 7 months postpartum. Blood lead was analyzed using graphite furnace atomic absorption spectroscopy. Mean blood lead level at delivery was 8.4 microg/dl (range: 1.8--23.4). Mean cortical and trabecular lead levels were 10.6 microg/g (range: nondetectable to 76.5) and 15.3 microg/g (range: nondetectable to 85.9), respectively, reflecting a population with elevated and diverse past and current lead exposure. The association of bone lead and breastfeeding with blood lead was estimated using generalized estimating equations. Breastfeeding practices and maternal bone lead were important predictors of blood lead level. After adjustment for bone lead and environmental exposure, women who exclusively breastfed their infants had blood lead levels that were increased by 1.4 microg/dl and women who practiced mixed feeding had levels increased by 1.0 microg/dl, in relation to those who had stopped lactation. These results support the hypothesis that lactation is directly related to the amount of lead released from bone.

Maternal bone lead as an independent risk factor for fetal neurotoxicity: a prospective study.

OBJECTIVE: A number of prospective studies have examined lead levels in umbilical cord blood at birth as predictors of infant mental development. Although several have found significant inverse associations, others have not. Measurement of lead levels in maternal bone, now recognized as the source of much fetal exposure, has the potential to serve as a better or complementary predictor of lead's effect on the fetus. Our objective was to compare lead levels in umbilical cord blood and maternal bone as independent predictors of infant mental development using a prospective design. METHODS: We recruited women who were giving birth at 3 maternity hospitals in Mexico City that serve a homogeneous middle-class community. Umbilical cord blood lead levels were measured by graphite furnace atomic absorption spectroscopy, and maternal lead levels in cortical (tibial) and trabecular (patellar) bone were measured within 4 weeks of giving birth using a 109-Cd K-x-ray fluorescence instrument. At 24 months of age, each infant was assessed using the Bayley Scales of Infant Development-II (Spanish Version). RESULTS: A total of 197 mother-infant pairs completed this portion of the study and had data on all variables of interest. After adjustment for other well-known determinants of infant neurodevelopment, including maternal age, IQ, and education; paternal education; marital status; breastfeeding duration; infant gender; and infant illness, lead levels in umbilical cord blood and trabecular bone were significantly, independently, and inversely associated with the Mental Development Index (MDI) scores of the Bayley Scale. In relation to the lowest quartile of trabecular bone lead, the second, third, and fourth quartiles were associated with 5.4-, 7.2-, and 6.5-point decrements in adjusted MDI scores. A 2-fold increase in cord blood lead level (eg, from 5 to 10 micro g/dL) was associated with a 3.1-point decrement in MDI score, which is comparable to the magnitude of effect seen in previous studies. CONCLUSION: Higher maternal trabecular bone lead levels constitute an independent risk factor for impaired mental development in infants at 24 months of age. This effect is probably attributable to mobilization of maternal bone lead stores, a phenomenon that may constitute a significant public health problem in view of the long residence time of lead in bone.

Breast-feeding practices in Mexico: results from the Second National Nutrition Survey 1999.

OBJECTIVE: To assess breast-feeding (BF) practices and determinants of exclusive BF (EBF) < 4 and < 6 months (mo) among women and infants < 23 mo in the NNS-1999. MATERIAL AND METHODS: BF practices from the day and night before the interview were ascertained, and median duration estimated. Determinants of EBF < 4 and < 6 mo were analysed by logistic regression models for complex surveys. RESULTS: Prevalence of EBF < 4 mo was 25.7%, and of < 6 mo 20.3%. The overall rate of continued BF (second year) was 30.9%, median duration of BF 9 mo, and the national proportion of children ever breast-fed 92.3%. The probability (p) of EBF < 4 mo was determined by infant age and sex, by maternal socio-economic level (SEL) and ethnicity, and by the interaction between infant sex and SEL. The pEBF < 6 mo was determined by infant age and length, by maternal ethnicity, and employment. CONCLUSIONS: EBF rates and duration are low in Mexico and have improved only slightly in the last 20 y. Infant and maternal characteristics determine the pEBF. If improvements in infant health are a national priority, aggressive interventions to promote and protect BF are urgently needed in Mexico, as well as formal evaluation of current initiatives. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Alimentos industrializados en la dieta de los preescolares mexicanos / Contribution of processed foods to the energy, macronutrient and fiber intakes of Mexican children aged 1 to 4 years

OBJETIVOS: Clasificar los alimentos consumidos por preescolares mexicanos, en relación con su proceso de elaboración y temporalidad: a) industrializados modernos (IM), b) industrializados tradicionales (IT) y c) no industrializados (NI). MATERIAL Y MÉTODOS: Con base en información del recordatorio de 24 horas de la Encuesta Nacional de Nutrición 1999 en niños de 1-4 años (n=1 070) se analizó la contribución de cada categoría de alimentos en energía, macronutrimentos y fibra. RESULTADOS: La contribución de energía a partir de IM e IT, respectivamente, fue: energía, 17 y 31 por ciento; proteína total, 14 y 25 por ciento; proteína vegetal, 10 y 10 por ciento; proteína animal, 17 y 34 por ciento; carbohidratos, 18 y 26 por ciento; fibra, 4 y 5 por ciento; grasa total, 15 y 41 por ciento; grasa saturada, 16 y 52 por ciento; y colesterol, 7 y 7 por ciento. CONCLUSIONES: Los alimentos industrializados aportan más de 39 por ciento de la energía, proteína animal, carbohidratos y grasas a la dieta de los preescolares mexicanos. Se recomienda la participación de la industria alimentaria para prevenir la mala nutrición infantil en México.

OBJECTIVE: To classify the foods consumed by Mexican children 1-4 years in three food categories according to the preparation process and temporality: a) Processed Modern Foods (PMF), b) Processed Traditional Foods (PTF) and c) Non-Processed Foods. MATERIAL AND METHODS: Twenty-four-hour dietary recalls were collected from the National Nutrition Survey 1999 in children 1-4 years (n =1070). The contribution of each food category to the total energy, macronutrient and fiber intakes was analyzed. RESULTS: The contribution of PMF and PTF was as follows, respectively: Energy: 17 percent, 31 percent; total protein: 14 percent, 25 percent; non-animal protein: 10 percent, 10 percent; animal protein: 17 percent, 34 percent; carbohydrates: 18 percent, 26 percent; fiber: 4 percent, 5 percent; total fat 15 percent, 41 percent; saturated fat 16 percent, 52 percent; and cholesterol 7 percent, 7 percent. CONCLUSIONS: The contribution of PF to the diets of Mexican children accounts for >39 percent of energy, total protein, animal protein, carbohydrates and fat. The authors recommend the participation of food industry to prevent malnutrition in children.

Multiple micronutrient supplementation and dietary energy intake in pregnant women

OBJECTIVE: To compare dietary intake of women supplemented with multiple micronutrients (MM) or iron only during pregnancy. MATERIALS AND METHODS: Design: Randomized, double-blind, controlled community-based trial. Setting: One semi-urban community in Central Mexico. Subjects: Pregnant women identified before week 13 of pregnancy, willing to provide informed consent. Interventions: Women were randomly assigned to receive daily supplementation with MM or iron only from recruitment until delivery. Supplements were delivered to the participants' home and compliance observed daily. Dietary intake was assessed by repeat 24-hr recall. Data were analyzed using non-parametric tests and multiple regression analysis to determine the impact of MM supplementation on dietary intake of energy and select micronutrients. RESULTS: During the third trimester, women in the MM group consumed more energy and iron from dietary sources than women in the iron only group. After adjustment for differences between the groups at baseline, women in the MM group consumed 111.3 kcal/day more (p<0.05) energy. The difference in iron intake was not significant after adjusting for the increase in energy intake. CONCLUSIONS: Women consuming MM supplements during pregnancy increased energy intake from dietary sources without a concurrent increase in micronutrient density. Future studies should include measures of appetite and physical activity during pregnancy to determine the implications of additional energy intake for weight gain and retention.

OBJETIVO: Comparar la dieta de mujeres suplementada con múltiples micronutrimentos (MM) o sólo con hierro durante el embarazo. MATERIAL Y MÉTODOS: Diseño: ensayo comunitario, aleatorizado, controlado, doble ciego. Lugar: una comunidad semiurbana en el México central. Participantes: mujeres embarazadas identificadas antes de la semana 13 de embarazo, dispuestas a entregar el consentimiento informado. Actividades: las mujeres fueron asignadas en forma aleatoria a recibir suplementación diaria con MM o exclusivamente hierro desde el reclutamiento hasta el parto. Los suplementos se entregaron en la casa de las participantes y se observó su cumplimiento con frecuencia diaria. El consumo dietético fue valorado por mediciones repetidas de recordatorio de alimentos de 24 h. Los datos se analizaron mediante pruebas no paramétricas y análisis de regresión múltiple, para determinar el impacto de la suplementación MM en el consumo dietético de energía y micronutrimentos seleccionados. RESULTADOS: durante el tercer trimestre, la mujer asignada al grupo MM consumió más energía y hierro de fuentes dietéticas que la mujer asignada al grupo de sólo hierro. Después de los ajustes para las diferencias entre grupos en la línea basal, la mujer del grupo MM consumió 111.3 kcal/día más (p< 0.05) de energía. La diferencia en el consumo de hierro no fue significante después de los ajustes para el incremento en el consumo de energía. CONCLUSIONES: la mujer que consume suplementos MM durante el embarazo aumenta el consumo de energía a partir de fuentes dietéticas sin un incremento concurrente en la densidad de micronutrimentos. Estudios futuros deberían incluir mediciones del apetito y de la actividad física durante el embarazo para determinar las consecuencias del consumo de energía adicional en la ganancia de peso y la retención.

Nutritional status of indigenous children younger than five years of age in Mexico: results of a national probabilistic survey

OBJETIVO: Comparar las prevalencias de desnutrición y anemia en niños indígenas y no indígenas menores de cinco años de edad en el ámbito nacional, por región, por zonas urbanas y rurales, y evaluar en qué medida la condición socioeconómica de la familia predice las diferencias. MATERIAL Y MÉTODOS: Se realizó una encuesta nacional probabilística en 1999 en México. Las familias indígenas fueron identificadas como aquellas en las cuales al menos una mujer entre 12 y 49 años de edad en el hogar hablara una lengua indígena. Las prevalencias de desnutrición (baja talla, emaciación y bajo peso) y anemia fueron comparadas entre niños indígenas y no indígenas. Se utilizaron razones de probabilidad para comparar prevalencias ajustando por las condiciones socioeconómicas de la familia y por otras variables. RESULTADOS: Las prevalencias de baja talla y de bajo peso fueron mayores en indígenas que en no indígenas. En el ámbito nacional y en zonas urbanas las prevalencias fueron casi tres veces mayores, mientras que en zonas rurales fueron +/- 2 veces mayores (p<0.05). No se encontraron diferencias en las prevalencias de emaciación (p>0.05). La prevalencia de anemia en indígenas fue un tercio mayor que en no indígenas en el ámbito nacional (p <0.05) y entre 30 y 60 por ciento mayor en áreas urbanas y en las regiones estudiadas (p<0.05), pero no fue estadísticamente significativa en áreas rurales (p>0.05). Estas diferencias se redujeron aproximadamente a la mitad al ajustar por las condiciones socioeconómicas, pero continuaron siendo significativamente superiores en niños indígenas (p<0.05). CONCLUSIONES: Los niños indígenas tienen mayor probabilidad de presentar baja talla y bajo peso que los no indígenas. Las diferencias son mayores en áreas urbanas y en las regiones geográficas con mejores condiciones de vida, y se explican principalmente por factores socioeconómicos. La probabilidad de anemia entre poblaciones fue sólo modestamente mayor en zonas urbanas que en zonas rurales, y las diferencias son explicadas en menor grado por factores socioeconómicos. Se recomienda el diseño y aplicación de políticas y programas para eliminar las diferencias abismales en estado nutricio entre niños indígenas y no indígenas en México.

Breast-feeding practices in Mexico: results from the Second National Nutrition Survey 1999

OBJETIVO: Evaluar las prácticas de lactancia y las determinantes de la lactancia exclusiva (LE) hasta <4 y <6 m, en mujeres con hijos menores de 24 m de la segunda Encuesta Nacional de Nutrición 1999. MATERIAL Y MÉTODOS: Las prácticas de lactancia se estimaron del día y la noche anteriores a la entrevista. Los determinantes de LE<4m y LE<6m fueron analizados mediante regresión logística para muestras complejas. RESULTADOS: La prevalencia de LE<4m fue 25.7 por ciento, y <6 m 20.3 por ciento. La tasa de lactancia continuada (segundo año) 30.9 por ciento, mediana de duración de lactancia 9 m, y proporción de amamantados alguna vez 92.3 por ciento. La probabilidad (p)LE<4m estuvo determinada por edad, y el sexo del infante, por el nivel socioeconómico y etnicidad maternas, y por la interacción entre el sexo y el nivel socioeconómico. La p LE<6m estuvo determinada por edad y la longitud del infante y por el empleo, etnicidad y nivel socioeconómico de la madre. CONCLUSIONES: La duración y prevalencia de LE son bajas en México, poco mejores que hace 20 años. Las características del infante y de la madre determinan la p LME. Para promover la salud del niño, es urgente implementar programas agresivos de protección y promoción de la lactancia, así como evaluar y adecuar formalmente los existentes.