Bioavailability of energy, nitrogen, fat, zinc, iron and calcium from rural and urban Mexican diets

Zinc Supplementation and Fortification in Mexican Children

BACKGROUND

Zinc is an essential micronutrient for human health. Approximately 1.4% of deaths worldwide are related to zinc deficiency. In Mexico, 33% of children younger than 5 years are zinc deficient.

OBJECTIVE

To give an overview of zinc supplementation and fortification in children younger than 5 years through the analysis of current regulations in Mexico, the availability of these products, and the opinion of Mexican experts in this field.

METHODS

We gave an overview of zinc supplementation and fortification strategies in the Mexican pediatric population by conducting a literature review of Mexican studies and national standards concerning zinc supplementation and fortification. Semistructured interviews were conducted with personnel from the main producers of zinc supplements and fortified products and from social assistance programs in Mexico.

RESULTS

Zinc supplementation in Mexico has been associated with reduction in the duration and incidence of diarrhea. Through interviews with experts, we identified several barriers in achieving adequate zinc consumption such as problems in social assistance programs that distribute zinc-fortified foods, lack of specific dietary recommendations regarding the intake of zinc, lack of regulation of nonpatented zinc supplements, and inconsistencies in public health actions due to political and administrative changes.

CONCLUSION

Despite current regulation and efforts made by social assistance programs, zinc deficiency continues to be a prevalent public health issue. Mexico requires an in-depth analysis of existing barriers and alternatives in order to reduce zinc deficiency.

The Nutritional Content of Common Bean (Phaseolus vulgaris L.) Landraces in Comparison to Modern Varieties

In terms of safe food and a healthy food supply, beans (Phaseolus spp.) are a significant source of protein, carbohydrates, vitamins and minerals especially for poor populations throughout the world. They are also rich in unsaturated fatty acids, such as linoleic and oleic acids. From the past to the present, a large number of breeding studies to increase bean yield, especially the common bean (P. vulgaris L.), have resulted in the registration of many modern varieties, although quality and flavor traits in the modern varieties have been mostly ignored. The aim of the present study, therefore, was to compare protein, fat, fatty acid, and some mineral content such as selenium (Se), zinc (Zn) and iron (Fe) of landraces to modern varieties. The landrace LR05 had higher mineral contents, particularly Se and Zn, and protein than the modern varieties. The landrace LR11 had the highest linoleic acid. The landraces are grown by farmers in small holdings for dual uses, such as both dry seed and snap bean production, and are commercialized with a higher cash price. The landraces of the common bean are, not only treasures that need to be guarded for the future, but also important genetic resources that can be used in bean breeding programs. The results of this study suggest that landraces are essential sources of important nutritional components for food security and a healthy food supply.

Assessment of Aflatoxin M1 and M2 exposure risk through Oaxaca cheese consumption in southeastern Mexico

The present study evaluated the exposure of Southeast Mexican population to Aflatoxin M1 (AFM1) and M2 (AFM2) through the consumption of Oaxaca cheese. The intake of Oaxaca cheese was assessed via a food 7-day dairy questionnaire (N = 1100, 2014 and 2015). Thirty Oaxaca cheeses were randomly sampled, and the origin of the samples was also investigated. AFM1 and AFM2 were quantified by HPLC-FD. The exposure was assessed through the combination of the Probabilistic Density Functions (probabilistic approach). The percentage of the population at risk was calculated through the population exceeding the toxicological reference values (TDI). The risk assessment revealed that the population at higher risk to AFM1 and AFM2 was the children, followed by the adolescents and adult women. To our knowledge, the present study is the first to assess the exposure risk of different age groups of a population to AFM1 and AFM2 through the consumption of cheese.

Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans

Plant-based diets contain less saturated fat and cholesterol and more folate, fibre and phytochemicals than omnivorous diets, but some micronutrients, especially zinc, are poorly bioavailable. The findings of studies exploring the zinc intake and zinc status in populations that habitually consume vegetarian diets are inconsistent. This study aims to investigate the effects of plant-based diets on dietary zinc intake and status in humans using systematic review and meta-analysis techniques. Thirty-four studies were included in the systematic review. Of these, 26 studies (reporting 48 comparisons) compared males and/or females consuming vegetarian diets with non-vegetarian groups and were included in meta-analyses. Dietary zinc intakes and serum zinc concentrations were significantly lower (-0.88 ± 0.15 mg day(-1), P < 0.001 and -0.93 ± 0.27 µmol L(-1), P = 0.001 respectively; mean ± standard error) in populations that followed habitual vegetarian diets compared with non-vegetarians. Secondary analyses showed greater impact of vegetarian diets on the zinc intake and status of females, vegetarians from developing countries and vegans. Populations that habitually consume vegetarian diets have low zinc intakes and status. Not all vegetarian categories impact zinc status to the same extent, but a lack of consistency in defining vegetarian diets for research purposes makes dietary assessment difficult. Dietary practices that increase zinc bioavailability, the consumption of foods fortified with zinc or low-dose supplementation are strategies that should be considered for improving the zinc status of vegetarians with low zinc intakes or serum zinc concentrations at the lower end of the reference range.

Chemical composition, starch digestibility and antioxidant capacity of tortilla made with a blend of quality protein maize and black bean

Tortilla and beans are the basic components in the diet of people in the urban and rural areas of Mexico. Quality protein maize is suggested for tortilla preparation because it presents an increase in lysine and tryptophan levels. Beans contain important amounts of dietary fiber. The objective of this study was to prepare tortilla with bean and assesses the chemical composition, starch digestibility and antioxidant capacity using a quality protein maize variety. Tortilla with bean had higher protein, ash, dietary fiber and resistant starch content, and lower digestible starch than control tortilla. The hydrolysis rate (60 to 50%) and the predicted glycemic index (88 to 80) of tortilla decreased with the addition of bean in the blend. Extractable polyphenols and proanthocyanidins were higher in the tortilla with bean than control tortilla. This pattern produced higher antioxidant capacity of tortilla with bean (17.6 μmol Trolox eq/g) than control tortilla (7.8 μmol Trolox eq/g). The addition of bean to tortilla modified the starch digestibility and antioxidant characteristics of tortilla, obtaining a product with nutraceutical characteristics.

Minerals (Zn, Fe, Ca and Mg) and Antinutrient (Phytic Acid) Constituents in Common Bean

In this study, the variation of zinc (Zn), iron (Fe), calcium (Ca) and magnesium (Mg) and the interference of phytic acid (PA) on their availability was investigated in 29 US grown and CIAT breeding genotypes of common bean. Fe levels showed the highest variation (8.9-112.9 mg kg^-1) followed by Ca (58.67-122.98 mg kg^-1) and Zn (30.90-64.60 mg kg^-1) while variability of Mg concentration (6.47-11.05 mg kg^-1) is the least among the mineral components. PA showed a wide range of variability (12.52-316.42 m kg^-1) and inversely correlated with Fe, Ca and Mg concentrations. The results of the minerals and PA concentration can be interpreted in terms of expected bio-availability of minerals and the correlation study indicated that the presence of high concentration of PA inhibit the availability of most minerals under study in common beans. We suggest that the genotypes, MIB466, MIB465, MIB152 and JaloEEP 558 could be considered as sources of high Zn and Vista and NUA56-1770 for high seed Fe. We also identified G122 for high Ca and JaloEEP558 genotype for high Mg. We conclude that there is scope for the enhancement of mineral contents of common bean by selecting suitable genotype and bean products require processing for dephytinization for the improvement of mineral availability.

Elementos traço e complicações obstétricas na gestação na adolescência

Minerais estão relacionados com todas as etapas de crescimento e diferenciação celular. Quando a gestação coincide com a adolescência a demanda nutricional necessária para ótimo desenvolvimento e crescimento materno e fetal aumenta consideravelmente. Apesar de existirem muitos estudos sobre as funções destes micronutrientes, pouco se sabe sobre suas atuações no resultado da gestação. Este trabalho objetivou revisar na literatura o papel do cobre, ferro, e zinco no resultado da gestação, em especial de gestantes adolescentes, focando intercorrências como baixo peso ao nascer, partos pré-termo, pré-eclampsia, abortos, dentre outras complicações associadas à gestação na adolescência. Os estudos já realizados são limitados, há a necessidade de promovê-los em países em desenvolvimento, onde a deficiência de micronutrientes e intercorrências possuem altos índices. Os benefícios da suplementação de minerais na redução da prevalência de déficits e na melhora dos estoques maternos têm sido demonstrados, mas dados sobre os benefícios potenciais para o feto são pouco conclusivos.

Poor iron status is more prevalent in Hispanic than in non-Hispanic white older adults in Massachusetts

Iron status and dietary correlates of iron status have not been well described in Hispanic older adults of Caribbean origin. The aim of this study was to evaluate iron status and describe dietary components and correlates of iron status in Hispanic older adults and in a neighborhood-based comparison group of non-Hispanic white older adults. Six hundred four Hispanic and non-Hispanic white adults (59-91 y of age) from the Massachusetts Hispanic Elders Study were included in the analysis. We examined physiological markers of iron status as well as dietary factors in relation to iron status. Dietary intake was assessed by FFQ. Our results revealed that Hispanics had significantly lower geometric mean serum ferritin (74.1 microg/L vs. 100 microg/L; P<0.001), lower hemoglobin concentrations (137+/-13 vs. 140+/-12 g/L; P<0.01), higher prevalence of anemia (11.5 vs. 7.3%; P<0.05), and suboptimal hemoglobin concentrations (<125 g/L) for this age group (21.4 vs. 13.3%; P<0.05). Iron deficiency anemia was higher (7.2% vs. 2.3%; P<0.05) in Hispanic women. Hispanics had lower mean intakes of total iron, vitamin C, supplemental vitamin C, and total calcium than did non-Hispanic whites. After adjusting for age, sex, BMI, alcohol use, smoking, total energy intake, inflammation, diabetes, and liver disease, intake of heme iron from red meat was positively associated and dietary calcium was negatively associated with serum ferritin. This population of Hispanic older adults was significantly more likely than their non-Hispanic white neighbors to suffer from anemia and poor iron status, particularly among women. Cultural variation in dietary patterns may influence iron availability and body iron stores and contribute to an increased risk for iron deficiency anemia among some Hispanic older adults.

Household dietary strategies to enhance the content and bioavailability of iron, zinc and calcium of selected rice- and maize-based Philippine complementary foods

Philippine complementary foods are predominantly plant-based, with a low content of readily available iron, zinc, and calcium, and a relatively high amount of phytate, a potent inhibitor of mineral absorption. Some of the phytate is water soluble, and hence can be removed by soaking. In this study we have compared the iron, zinc, and calcium content, and estimated iron and zinc bioavailability of rice- and maize-based Filipino complementary foods prepared with and without soaking and/or enrichment with chicken liver, egg yolk, small soft-boned fish, and mung bean grits. Analysis of iron, zinc, and calcium were performed by atomic absorption spectrometry, and phytate (based on hexa-(IP6) and penta-inositol phosphate (IP5) by HPLC; corresponding [Phy]/[Fe] and [Phy]/[Zn] molar ratios were calculated as predictors of iron and zinc bioavailability. Addition of chicken liver, followed by egg yolk, resulted in the greatest increases in iron and zinc content for both the rice- and maize-based complementary foods, whereas addition of small dried fish with bones had the greatest effect on calcium. The IP5 + IP6 content and [Phy]/[Zn] molar ratios were higher in the maize- than rice-based complementary foods, and were reduced by soaking, although only the maize plus mung bean grits, with and without soaking, had [Phy]/[Zn] molar ratios above 15. Enrichment with animal protein or soaking has the potential to enhance the content of absorbable iron, zinc, and probably calcium to varying degrees in rice- and maize-based Philippine complementary foods.

A double-blind, randomized, clinical trial of the effect of vitamin A and zinc supplementation on diarrheal disease and respiratory tract infections in children in Mexico City, Mexico

BACKGROUND

The efficacy of micronutrient supplementation in improving childhood health and survival in developing countries may be specific to the micronutrient used and health outcome measured.

OBJECTIVE

We evaluated the effect of vitamin A and zinc supplementation on overall rates of childhood diarrheal disease and respiratory tract infections and rates stratified by household and personal characteristics.

DESIGN

A double-blind, randomized, placebo-controlled trial was carried out in which 736 children aged 6-15 mo living in a periurban area of Mexico City were assigned to receive vitamin A every 2 mo, zinc daily, vitamin A and zinc together, or placebo. Children were followed for 12 mo to determine overall counts of diarrheal episodes and respiratory tract infections.

RESULTS

Vitamin A supplementation was associated with a 27% increase in diarrheal disease [risk ratio (RR): 1.27; 95% CI: 1.10, 1.45; P < 0.001] and a 23% increase in cough with fever (RR: 1.23; 95% CI: 1.02, 1.47; P = 0.02), whereas zinc had no effect on these outcomes. Vitamin A supplementation decreased diarrhea in children from households with dirt floors but increased diarrhea in children from households with nondirt floors, piped water, and indoor bathrooms. Zinc supplementation decreased diarrhea in children from households with dirt floors and whose mothers were more educated. Vitamin A supplementation increased cough with fever in children from less-crowded households that lacked indoor bathrooms and in children of less-educated mothers.

CONCLUSIONS

Vitamin A increases diarrheal disease and respiratory tract infections in young children in periurban areas of Mexico City. Vitamin A and zinc have more heterogeneous effects in different subgroups of children.

Calcium absorption from corn tortilla is relatively high and is dependent upon calcium content and liming in Mexican women

Corn tortillas are the staple food of Mexico. During their preparation, calcium is added to the tortillas; therefore, tortillas are the main source of calcium for a large proportion of the population. The bioavailability of calcium from lime-treated tortillas in humans is not known. The objectives of the present study were to determine calcium absorption from corn tortilla, to determine the effect of lime treatment on calcium absorption from corn tortilla, and to compare calcium absorption from tortilla prepared with a commercial corn flour and tortillas prepared with the traditional lime treatment at home. Nonpregnant, nonlactating women (n = 9) were administered 3 different treatments: 1) 180 g of corn tortilla prepared from corn flour with no lime treatment (CF), 2) 180 g of corn tortilla prepared from lime-treated commercial corn flour (LTCCF), or 3) 180 g of corn tortillas prepared from lime-treated home-prepared corn flour (LTHCF). Calcium absorption was measured using an established dual-tracer stable isotope technique. Calcium absorption of CF, LTCCF, and LTHCF was (mean +/- SD): 44 +/- 3.2, 32 +/- 4.4, and 30 +/- 2.4%, respectively; the fractional calcium absorption from CF differed from that of either LTCCF or LTHCF (P < 0.01). The total amount of calcium absorbed per treatment was higher in LTHCF (98.10 mg +/- 21.7) than in LTCCF (59.9 mg +/- 23.7, P < 0.001) and CF (3.78 mg +/- 0.9, P < 0.0.001). In conclusion, calcium absorption from corn tortillas is high and dependent on calcium concentration. The addition of calcium during lime treatment increases calcium concentration and total calcium absorption.

The addition of milk or yogurt to a plant-based diet increases zinc bioavailability but does not affect iron bioavailability in women

The addition of milk and milk-based products to the diets of individuals subsisting on plant-based diets was reported to have positive effects on nutritional status and functional outcomes such as growth, morbidity, and cognition. We examined the effect of the addition of milk or yogurt on the bioavailability of zinc and iron from a plant-based rural diet. The subjects were 48 Mexican women (30.9 +/- 5.7 y) who habitually consumed a plant-based diet. The women were assigned to 1 of 3 groups: 1) the typical rural Mexican diet, 2) that diet with milk added, or 3) that diet with yogurt for 13 d. Zinc absorption was measured after extrinsically labeling meals with (67)Zn and an i.v. dose of (70)Zn; iron absorption was measured by extrinsically labeling meals with (58)Fe and a reference oral dose of (57)Fe. Including milk and yogurt in the diet increased zinc absorption by 50 and 68%, respectively (P < 0.05). The 3 groups did not differ in the percentage iron absorption. The total amount of zinc absorbed was increased (P < 0.05) by 70% when milk was added to the meal and 78% when yogurt was added. The total amount of iron absorbed did not differ among the groups. The addition of milk and yogurt to a plant-based diet high in phytate increases zinc bioavailability without affecting iron bioavailability.

Zinc absorption from low-phytate hybrids of maize and their wild-type isohybrids

BACKGROUND

Identification of allelic variants in a single gene that determine the phytate content of maize kernels and the subsequent breeding of low-phytate maize have facilitated studies designed to determine quantitatively the effects of maize phytate on the bioavailability of minerals in maize.

OBJECTIVE

The objective was to determine the relation between the fractional absorption of zinc (FAZ) and the phytate content and phytate:zinc molar ratios of maize tortillas prepared from hybrids with different phytate contents.

DESIGN

Six healthy adults were fed, as the only food for 2 d, maize tortillas prepared from 1 of 2 low-phytate mutants: lpa1-1 (lpa1-1-LP) or Nutridense Low Phytate (ND-LP), which have phytate reductions of approximately 60% and approximately 80%, respectively, compared with their respective wild-type isohybrids. Four additional subjects were fed tortillas prepared from the corresponding wild-type isohybrids (lpa1-1-WT and ND-WT) according to the same study design. Meals were extrinsically labeled with zinc stable isotopes, and FAZ was determined with a dual-isotope-tracer ratio technique. Overall FAZ values were examined in relation to dietary phytate and phytate:zinc molar ratios by using a mixed nonlinear regression model.

RESULTS

The mean (+/-SD) FAZ values from tortillas prepared from ND-LP, lpa1-1-LP, lpa1-1-WT, and ND-WT were 0.38 +/- 0.07, 0.28 +/- 0.04, 0.15 +/- 0.07, and 0.13 +/- 0.05, respectively. A negative relation (P < 0.001) was found between FAZ and both dietary phytate and the phytate:zinc molar ratio. The effect of dietary zinc (8-14 mg Zn/d) under these experimental conditions was not significant.

CONCLUSIONS

FAZ from maize tortillas is positively related to the extent of phytate reduction achieved with low-phytate hybrids.

Plasma total homocysteine in Mexican rural and urban women fed typical model diets

OBJECTIVE

The purpose of the present work was to determine the fasting plasma total homocysteine (tHcy) levels and the time-course response of tHcy concentrations after the consumption of urban and rural Mexican model diets in two groups of Mexican women from urban and rural areas.

METHODS

Thirty-three adult women (age range = 18-49 y) were studied. Fifteen women were from a rural community in the state of Mexico. The other 18 were from cities and consumed diets that regularly included an important amount of animal foods. The study was designed as a two-period crossover study in which subjects consumed the model urban or rural diet in a 2-wk interval. Seven milliliters of venous blood was drawn before ingestion of experimental diets (basal) to measure total cholesterol, high-density lipoprotein cholesterol, triacylglycerol, tHcy, folate, vitamin B12, and methionine. Blood samples were then obtained 30, 60, 90, 180, and 240 min after the beginning of meal consumption.

RESULTS

The rural and urban groups showed similar concentrations of tHcy 4 h after meal consumption and after fasting. However, the urban and rural groups had higher methionine plasma concentrations after the urban diet than after the rural diet. In contrast, there was no significant difference in methionine plasma levels between the rural and urban groups with each diet. Those women with low tHcy concentrations maintained those values over the study period, and those with high tHcy concentrations maintained those values. There was no significant difference in tHcy concentrations due to consumption of the two diets (P = 0.31) or the interaction between population and diet (P = 0.84). However, there was a significant difference in the concentration of tHcy between the rural (8.73 +/- 0.17 microM/L) and the urban (9.27 +/- 0.13 microM/L) populations (P = 0.01). In both groups, average tHcy concentration was in the normal range. In both populations, the nutrition status for folate and vitamin B12 was adequate, although plasma folate concentration was significantly lower in the rural population than in the urban population (P < 0.01). Plasma vitamin B12 concentrations were similar in both groups. No subject had low plasma vitamin B12.

CONCLUSIONS

Plasma tHcy concentrations in rural and urban Mexican women were within the range considered adequate; however, urban women showed significant higher concentrations than did rural women independently of the consumed diet and the plasma methionine concentration. These results indicated that there is no short-term variation in plasma tHcy due to the consumption of rural or urban diets.

Zinc and copper: proposed fortification levels and recommended zinc compounds

Micronutrient fortification of foods is now a highly relevant tool worldwide for overcoming micronutrient deficiency. Recent data show that subclinical zinc deficiency is widespread; in Mexico a national survey showed that 25% of children less than age 11 y had plasma zinc concentrations below 10.0 micromol/L (65 microg/dL). Copper deficiency in populations is unknown but copper supplementation is recommended to accompany zinc supplementation. Of the foods available for fortification, staple cereals are very good candidates for reducing micronutrient deficiencies. Because of its higher stability and lower cost, we recommend fortification of cereal flours with zinc oxide, which is absorbed as well as the less stable and more expensive forms of zinc. Depending on the amount of the food that is expected to be eaten, zinc fortification of staple foods could be 20-50 mg/kg of flour. For copper fortification the safer compound is copper gluconate. Copper sulfate is significantly less expensive, but an evaluation of potential physicochemical reactions that affect the final food product is recommended. The suggested amount of copper added to staple foods is 1.2-3.0 mg/kg of flour. For food supplements designed as part of supplementation programs to reduce micronutrient deficiency in children less than age 3 y, a dose of the final product (usually approximately 40-50 g) should contain approximately 4-5 mg of zinc and approximately 0.2-0.4 mg of copper depending on the habitual diet, magnitude of deficiencies and period of supplementation.

The efficacy of a local ascorbic acid-rich food in improving iron absorption from Mexican diets: a field study using stable isotopes

BACKGROUND

One potentially sustainable approach to improving iron status at the community level is to encourage the consumption of local ascorbic acid-rich foods, in conjunction with meals high in nonheme iron.

OBJECTIVE

The study, conducted in rural Mexico, measured stable isotopes of iron to evaluate the effect on iron absorption of the addition of 25 mg ascorbic acid as agua de limón (limeade) to 2 typical meals per day for 2 wk.

DESIGN

Fifteen nonpregnant, nonlactating, iron-deficient (ferritin < 12 microg/L) women (x +/- SD age: 28.3 +/- 7.7 y) fasted overnight and were brought to a community clinic. After an initial blood sample, subjects consumed 0.25 mg (57)Fe with both breakfast and lunch for 14 d. On day 29, another blood sample was taken, and a reference dose of 2.7 mg (58)Fe with 25 mg ascorbic acid was given. For the following 15 d, participants consumed 0.25 mg (57)Fe added to both breakfast and lunch with 25 mg ascorbic acid added to each meal as limeade. A final blood sample was taken on day 59.

RESULTS

Iron absorption was calculated from recovery of isotopes in blood obtained 14 d after administration of each isotope. When 25 mg ascorbic acid as limeade was added to test meals twice a day for 2 wk, iron absorption increased significantly (P < 0.001) in every subject: the mean absorption rose from 6.6 +/- 3.0% to 22.9 +/- 12.6%.

CONCLUSIONS

The consumption of 25 mg ascorbic acid as limeade twice daily with meals substantially improved iron absorption and may improve the iron status of nonpregnant, nonlactating, iron-deficient women.

Ascorbic acid from lime juice does not improve the iron status of iron-deficient women in rural Mexico

BACKGROUND

Although ascorbic acid (AA) increases dietary iron bioavailability, there has been no food-based community trial of its efficacy in improving iron status.

OBJECTIVE

The objective was to assess the efficacy of 25 mg AA as agua de limón (limeade), consumed with each of 2 daily meals, in improving the iron status of iron-deficient women.

DESIGN

Two rural Mexican populations were randomly assigned to an AA or a placebo group, each with 18 iron-deficient women. The AA group was given 500 mL limeade containing 25 mg AA twice a day, 6 d/wk, for 8 mo. The placebo group was given a lime-flavored beverage free of AA or citric acid. Beverages were consumed within 30 min of 2 main daily meals. Data were collected on morbidity (3 times/wk), dietary intake (on 6 d), socioeconomic status, parasites (twice), medical history, and response to treatment. Blood samples at 0, 2, 4, 6, and 8 mo were analyzed for hemoglobin, plasma AA, plasma ferritin, transferrin receptors, and C-reactive protein.

RESULTS

AA intake was significantly (P < 0.0001) higher in the AA group, but nonheme iron, heme iron, and phytic acid intakes did not differ significantly. Plasma AA was significantly (P < 0.01) higher in the AA group at 2, 4, 6, and 8 mo. There were no final differences between groups in hemoglobin, plasma ferritin, or transferrin receptor concentrations or in the ratio of transferrin receptors to plasma ferritin after control for initial concentrations.

CONCLUSION

Increasing dietary AA by 25 mg at each of 2 meals/d did not improve iron status in iron-deficient women consuming diets high in phytate and nonheme iron.

Negative calcium balance during lactation in rural Mexican women

BACKGROUND

Additional calcium is required during lactation, and several calcium regulatory factors are involved in calcium balance. In lactating rural women who have marginal nutrition and consume a high-fiber diet, negative calcium balance may be expected.

OBJECTIVE

We evaluated calcium balance and its association with potential calcium regulatory factors in lactating, rural Mexican women who had marginal nutrition and consumed a high-fiber diet.

DESIGN

This cross-sectional study included women at 1, 3, 6, and 12 mo of lactation (L1, L3, L6, and L12 groups) and women who had weaned their infants (W group). Age-matched, nonlactating women (NL group) were also included. Calcium balance and concentrations of calcium regulatory factors were determined. Correlation analysis was performed by using data from all of the lactating women.

RESULTS

Calcium balance in the L1, L3, and L6 groups was negative and was significantly different (P < 0.05) from that in the W and NL groups. Serum parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)(2)D] concentrations were significantly higher (P < 0.05) in the W group than in the L and NL groups. Calcium balance was positively associated with serum estradiol concentrations (r = 0.58, P < 0.05) and negatively associated with serum 1,25-(OH)(2)D concentrations (r = -0.52, P < 0.05). Breast-milk calcium concentrations correlated positively with serum PTH-related peptide (PTHrP) concentrations (r = 0.51, P < 0.05) and negatively with serum estradiol concentrations (r = -0.57, P < 0.05).

CONCLUSIONS

Negative calcium balance was observed during lactation in rural Mexican women who consumed a high-fiber diet. Furthermore, the data suggest that the hormones estradiol and PTHrP are involved in the regulation of calcium balance and of the calcium content of milk during lactation.

Negative balance of calcium during lactation in marginally nourished women

Thirty-three rural Mexican women (age, 18-36y; weight, 50.3+/-3 kg; height, 148.3+/-2 cm) were studied under metabolic balance conditions. The objectives were to study the metabolic balances of calcium and phosphorus at the 1st, 3rd, and 6th months of lactation and postweaning and to determine the incorporation of calcium and phosphorus in milk. Subjects were divided into 5 groups of 5 to 10 each, representing: the 1st, 3rd, and 6th month of lactation, postweaning, and a control group of nonpregnant, nonlactating women. Metabolic balance was determined using identical diets and analysis of 24-hour urine (3 d), 72-hour feces, and 24-hour milk samples. Calcium content was determined by atomic absorption spectrophotometry and phosphorus by a colorimetric method. Calcium content in milk was similar at the 1st, 3rd, and 6th months. Positive calcium balances were observed in the control group, while balances were very negative in all lactation groups (-721.6+/-248 mg/d). Calcium urinary excretion was higher in the control and postweaning groups (P < 0.05), suggesting a regulatory mechanism to conserve calcium during lactation. No differences were observed in phosphorus content in milk at the 1st, 3rd, and 6th months. Positive balances were observed in the control and postweaning groups (331+/-139 and 87.1+/-130 mg/d, respectively, mean +/- SD), while the lactation groups presented more subjects (approximately 75%) in negative balance (mean +/- SD of -180.6+/-392 to -439+/-146 mg/d). High fecal calcium and phosphorus excretion (approximately 1,500 mg/d) likely contributed to the negative balance during lactation.

Iron and zinc bioavailability in rats fed intrinsically labeled bean and bean-rice infant weaning food products

Beans are the core of the Latin American diet and contain iron and zinc. However, the bioavailability of these trace minerals from beans is low. The objective of this study was to determine if the bioavailability of iron and zinc could be improved with the use of fermentation and germination processing technologies. Black beans native to Costa Rica were grown hydroponically with either radioactive iron or zinc. The influence of fermentation and germination on iron and zinc bioavailability from intrinsically labeled infant weaning food products based on black beans and beans-rice was determined in rats. Mineral bioavailability was determined using whole-body (59)Fe retention for iron, and whole-body (65)Zn retention and incorporation of radiolabel into bone for zinc. Percent absorption of (59)Fe from fermented products ranged between 48.0 and 58.0. Percent absorption of (65)Zn ranged from 57.0 to 64.0. Fermentation did not increase iron bioavailability in rats fed fermented beans without rice. Fermentation of cooked beans significantly increased zinc retention. Germination significantly enhanced iron retention from cooked beans from 46 to 55% and from cooked beans-cooked rice from 34 to 48%. Germination significantly improved zinc absorption and retention from cooked beans without added rice.

Basal urinary zinc/creatinine ratio as an indicator of dietary zinc intake in healthy adult women

OBJECTIVE

To study, in healthy women, the correlation between the basal urinary zinc/creatinine ratio and dietary zinc intake.

SUBJECTS

A group of 36 healthy female University students was evaluated. Mean age and body weight were, respectively, 25.6+/-3.3 years and 54.4+/-7.0 kg.

METHODS

Basal urine was collected; Zn was determined by AAS and Creatinine (Creat) by the Jaffe method. A nutritional survey of seven days was recorded. Mean daily dietary intake of energy (DE) and zinc (DZn) were calculated according to the INCAP and English or German Food Composition Tables, respectively.

RESULTS

Mean dietary daily intake were as follows (x +/- SD): Energy (kcal): 1606+/-570; zinc (mg): 9.1+/-3.8; basal urine Zn/Creat ratio: 0.41+/-0.24. Individual values of the Zn/Creat ratio correlated with dietary Zn (r=0.481, p=0.0339); data grouped according to ranges of dietary Zn fit the following equation: Zn/Creat=0.160+/-0.034 DZn (mg/day); (r=0.870, p=0.00497).

CONCLUSIONS

These results showed that the basal urinary Zn/Creat ratio could be a useful indicator of dietary Zn intake in healthy adult women.

Iron and zinc supplementation improves indicators of vitamin A status of Mexican preschoolers

BACKGROUND

The coexistence of multiple micronutrient deficiencies is a widespread public health problem in many regions of the world. Interactions between zinc deficiency and vitamin A metabolism have been reported but no longitudinal studies have evaluated the effect of iron deficiency on vitamin A.

OBJECTIVE

The objective of this study was to investigate the effect of supplementation with iron, zinc, or both on vitamin A and its metabolically related proteins retinol binding protein (RBP) and transthyretin.

DESIGN

The study was a longitudinal, double-blind, placebo-controlled trial in which 219 rural Mexican children aged 18-36 mo were randomly assigned to receive 20 mg Zn/d, 20 mg Fe/d, 20 mg Zn/d plus 20 mg Fe/d, or placebo.

RESULTS

Six months after supplementation, plasma retinol increased in all supplemented groups. Compared with placebo, zinc supplementation was associated with significantly higher plasma retinol and transthyretin but the increase in RBP was not significant. Iron supplementation significantly increased plasma retinol, RBP, and transthyretin. Supplementation with zinc plus iron significantly increased plasma retinol but not RBP or transthyretin. Children deficient in zinc, iron, or vitamin A (as indicated by nutrient plasma concentration) at the beginning of the study had a significantly greater increase in retinol than did children with adequate nutrient status.

CONCLUSIONS

Supplementation with zinc, iron, or both improved indicators of vitamin A status. The results of this study agree with previous observations of a metabolic interaction between zinc and vitamin A and suggest an interaction between iron and vitamin A metabolism.

Metabolizable energy of high non-starch polysaccharide-maintenance and weight-reducing diets in men: experimental appraisal of assessment systems

We have examined the reliability of several food energy assessment systems for healthy men. The predictions of metabolizable energies were compared with determinations made in energy balance studies with three maintenance diets (12 MJ/d); one of the diets was moderate in non-starch polysaccharide (NSP; 2.1% of gross energy) and two were higher in NSP (3.5-4.6% of gross energy). A fourth diet was a submaintenance (6 MJ/d) high NSP (7% gross energy) diet. Discrepancies between the different food energy assessment systems and the determined metabolizable energy values ranged between 0 and 15%. With the maintenance diets, the Atwater specific factor system had errors generally within 6% of the determined value and a limit of agreement (bias +2SD) for diets of 10%. This accuracy compares with errors of 2% for both the originally published assessment of this system and a more recent general formula; both systems were without bias with increasing NSP content of the diets but the latter had limits of agreement within 3%. In contrast, the Atwater general, the European general and a recent FDA general formula showed increasing bias with increasing NSP intake. All of the general energy assessment systems overpredicted metabolizable energy from the high NSP submaintenance diet, which shows that even the least biased and most reliable energy assessment system that we identified applies to maintenance diets only; thus a correction has to be made for submaintenance diets.

Assessment of the embryotoxic potential of the total hydrolysis product of fumonisin B1 using cultured organogenesis-staged rat embryos

Aminopentol (AP1) is the total hydrolysis product of fumonisin B1 (FB1), the major and best characterized of the fumonisins, which are mycotoxins that are common contaminants of corn and corn meal. Some human populations expected to have significant exposure to AP1 have a high incidence of babies born with neural tube defects (NTD). The embryotoxicity of AP1 was evaluated in cultured rat embryos. Gestation day 9.5 embryos were exposed to 0, 3, 10, 30, 100 or 300 microM AP1 throughout the entire 45-hr culture period. At 100 microM AP1, growth and overall development were reduced significantly. There was also a significant increase in the incidence of abnormal embryos. 29% of the embryos had NTD, and 36% of the embryos had other abnormalities. At 300 microM AP1, the incidence of NTD was 15%, and 85% of the embryos had other abnormalities. These findings suggest that AP1, at concentrations of 100 microM and above, can induce NTD in organogenesis-stage cultured rat embryos. However, these NTD are in conjunction with significant overall retardation of growth and development as well as significant increases in the incidence of other defects. These studies also showed, when compared with previous findings, that AP1 is over 100-fold less toxic than FB1 to cultured rat embryos.

Dietary management of acute diarrhea with local foods in a Guatemalan rural community

A community-based, randomized trial was conducted to evaluate a locally available diet for the management of acute diarrhea (n = 99 episodes) in 90 Guatemalan children, 4-42 months of age. The Test Diet (TD), a combination of a semi-solid pap (maize flour, black beans, oil) and a liquid gruel, Incaparina (maize flour, cotton seed flour, sugar), in addition to breast-milk and other home foods (group TD, n = 45 episodes) was offered for 14 d and compared to usual home feeding (group HF, n = 54 episodes). Diarrhea episodes after admission were significantly shorter for group TD (median 2.0 d) than group HF (median 4.4 d, p = 0.003) after adjusting for potential confounders. Weight gains did not differ significantly between groups. We conclude that community-based dietary management of acute childhood diarrhea using energy-dense, locally available foods is feasible and may shorten diarrhea duration. This may encourage mothers to follow recommendations for continued feeding during diarrhea in developing country environments.

The nutritional adequacy of a limited vegan diet for a Controlled Ecological Life-Support System

Purdue University, as well as the Johnson and Kennedy Space Centers and NASA Ames Research Center, are investigating approximately 5-10 plants that will be grown hydroponically to provide not only the energy and nutrients, but also the oxygen for humans habitating in Mars and lunar bases. The growth and nutritional status of rats fed either a control diet (adequate in all macro- and micronutrients) or a strict vegetarian diet consisting of 5 (vegan-5) or 10 (vegan-10) candidate crop species were investigated. In addition, vegan-10 diets were supplemented with mineral and/or vitamin mix at a level similar to the control diets to assess the effect of supplementation on nutrient status. The assessment of inedible plant material as an alternative food source was also investigated. Results of this study demonstrated that consumption of the vegan-10 diet significantly improved weight gain of rats compared to that for rats fed the vegan-5 diet. Mineral supplementation, at a level present in the control diet, to the vegan-10 diet improved growth and nutrient status, but growth was significantly lower compared to the control-fed rats. Inclusion of inedible plant material, high in ash content, improved some indices of nutrient status, without improving growth.

Consumption of dietary fiber in rural Mexico

The average per capita intake of dietary fibre and the relative contribution of different foods to its intake in the Mexican rural population was studied. Food consumption data were obtained from the National Nutrition Surveys of 1979 (21,248 families in 219 rural Mexican communities), and from a similar survey of the same communities in 1989 (20,759 families). Average per capita intake of total dietary fibre (TDF) ranged from 19.8 to 34.0 g/d (average 27.2 ± 3.3) in 1979 and from 17.5 to 27.1 g/d (average 22.5 ± 2.2) in 1989. About 13% of TDF in both surveys was contributed by soluble dietary fibre. Of the 19 regions of the country, 18 exhibited a significant reduction in TDF intake from 1979 to 1989 (p < 0.001). With the exception of two regions on the northern border, maize was the major single source of TDF (from 31 to 74% of TDF). The implication of these observations on disease patterns needs to be studied.

Calcium intakes of Mexican Americans, Cubans, Puerto Ricans, non-Hispanic whites, and non-Hispanic blacks in the United States

OBJECTIVE

To compare dietary calcium intakes from food in Mexican Americans, Cubans, Puerto Ricans, non-Hispanic whites, and non-Hispanic blacks aged 11 through 74 years.

DESIGN

Population survey data from the Hispanic Health and Nutrition Examination Survey and the second National Health and Nutrition Examination Survey were used to calculate calcium intake from a single 24-hour recall. These data were compared by age and sex between the five population groups. Food sources of calcium in the three Hispanic groups were also examined using 24-hour recall data.

SUBJECTS

The sample consisted of 11,773 non-Hispanic whites, 1,728 non-Hispanic blacks, 4,739 Mexican Americans, 1,076 Cubans, and 1,835 Puerto Ricans.

MAIN OUTCOME MEASURES

Mean calcium intake, percentage intake of Recommended Dietary Allowance, and, for Hispanics, food sources of calcium.

STATISTICAL ANALYSES

Means were compared within age and sex groups between the five population groups using a t test.

RESULTS

Calcium intakes from food in the three Hispanic groups were similar to intakes of non-Hispanic whites and higher than intakes of non-Hispanic blacks. Although dairy foods were the main sources of calcium for Hispanics, corn tortillas were important calcium sources among Mexican Americans. Women consumed less calcium than the Recommended Dietary Allowance in all age and racial or ethnic groups.

APPLICATIONS

When assessing calcium intakes of the three Hispanic groups, ethnic differences in food sources of calcium need to be considered. Efforts to increase calcium intake in Hispanics also need to account for ethnic differences.

The nutrition CRSP: what is marginal malnutrition, and does it affect human function?

This review of the Nutrition Collaborative Research Support Program (Nutrition CRSP) describes the results of a longitudinal study of the effects of marginal malnutrition on human function in Egypt, Kenya, and Mexico. Growth-stunting occurred soon after birth and was associated with cognitive and behavioral deficits in infancy and childhood. Maternal nutritional status was implicated in this phenomenon. All three population groups had poor dietary quality and multiple micronutrient deficiencies, which were associated with poor function. Energy deficiency was a problem only in Kenya.