Zinc nutriture and pregnancy outcome

A critical analysis of various post-harvest arsenic removal treatments of rice and their impact on public health due to nutrient loss

Rice (Oryza sativa L.) is particularly susceptible to arsenic (As) accumulation. Currently, to decrease the level of As accumulated in rice, various post-harvest methods, i.e., polishing, parboiling, pH-dependent soaking, washing, and cooking at different rice-to-water ratios (r/w), are being focused, because it removes significant amount of As from rice grain. Depending upon the rice variety and type, i.e., rough (with husk), husked (without husk/brown), or polished rice, these methods can remove 39-54% As by parboiling, 38-55% by polishing, 37-63% by soaking, and 6-80% by washing and cooking. Infants are highly vulnerable to As exposure; thus, these methods can be helpful for the production of rice-based infant foods. Although concern arises during the use of these methods that apart from decreasing the level of As in rice grain, they also lead to a significant loss of nutrients, such as macro- and micro-elements present in rice. Among these discussed methods, parboiling curtails 5-59%, polishing curtails 6-96%, soaking curtails 33-83%, and washing and cooking in different r/w reduce 8-81% of essential nutrients resulting in 2-90% reduction in contribution to the RDI of these nutrients through rice-based diet. Thus, these post-harvest arsenic removal methods, although reduce arsenic induced health hazard, but may also lead to malnutrition and compromised health in the population based on rice diet. There is a need to explore another way to reduce As from rice without compromising the nutrient availability or to supplement these nutrients through grain enrichment or by introducing additional dietary sources by changing eating habits; however, this may impose an extra economic burden on people.

Zinc deficiency among pregnant women around Lake Awasa, Hawassa City, Ethiopia: a cross-sectional analysis

Zinc deficiency (ZD) during pregnancy has far-reaching consequences on the mother, fetus and subsequent child survival. Therefore, the present study aimed to assess the prevalence and associated factors of ZD among pregnant women around Lake Awasa, Hawassa City, Ethiopia. To this end, a facility-based cross-sectional study was conducted on 333 randomly sampled pregnant women from 08 April to 08 May 2021. The socio-economic, dietary intake, water, sanitation and hygiene, obstetric, and maternal health data were collected through face-to-face interviews. Moreover, on-spot blood and stool samples were taken. Descriptive statistics and binary and multivariable logistic regression analysis were conducted. The prevalence of ZD was 58⋅6 % (95 % CI 53⋅31, 63⋅89). The poorest (AOR = 3⋅28; 95 % CI 1⋅26, 8⋅50) and poor (AOR = 2⋅93; 95 % CI 1⋅14, 7⋅54) wealth quintiles, four of more family size (AOR = 1⋅84, 95 % CI 1⋅10, 3⋅35), poor dietary diversity (AOR = 4⋅11; 95 % CI 2⋅11, 7⋅62), not eating snacks (AOR = 3⋅40; 95 % CI 1⋅42, 8⋅15), not consuming fish (AOR = 3⋅53; 95 % CI 1⋅65, 7⋅56) and chicken (AOR = 2⋅53; 95 % CI 1⋅31, 4⋅88) at least once a month, and intestinal parasitic infection (AOR = 2⋅78; 95 % CI 1⋅52, 5⋅08) predicted zinc deficiency. In conclusion, ZD is a public health problem among pregnant women around Lake Awasa. The present study demonstrated that poor socio-economic status, large family size, poor nutritional practices and intestinal parasitic infection determine the zinc status in the present study area. The findings suggest the need for further analysis to deepen the understanding about ZD and consideration of livelihood in interventions to prevent and control ZD among pregnant women in Hawassa City, Ethiopia.

Zinc homeostasis in immunity and its association with preterm births

Preterm birth is among the most common adverse pregnancy outcomes and is the leading cause of neonatal mortality and morbidity. While trace elements are essential for humans, their specific roles in the prenatal period remain unexplored. Zinc, a ubiquitous element plays a pivotal role in protein synthesis, cell division, nucleic acid metabolism, apoptosis, ageing, reproduction, immunological as well as antioxidant defense mechanism. Although zinc quantities are very small in body tissue, it is involved in every conceivable biochemical pathway which is critical for the performance of various functions necessary to sustain life. Owing to the multifactorial role of zinc, it is not possible to attribute a certain zinc dependent mechanism in pre-term births. Although the effect of zinc deficiency on immunity, its impact on maternal function and health as well as its role in the developing foetus is well documented, much less attention has been given to the understanding of micronutrient zinc homeostasis in immunity and its association with preterm births. Despite extensive research, the pathway by which zinc regulates pregnancy outcomes as well as the function of immune cells in controlling the delivery status (term/ preterm) is still obscure. The present review aims to focus on the understanding of relationship of micronutrient zinc homeostasis in immunity and its association with preterm births.

Factors Associated With Neural Tube Defects Among Newborns Delivered at Debre Berhan Specialized Hospital, North Eastern Ethiopia, 2021. Case-Control Study

BACKGROUND

Neural tube defects are severe congenital malformations secondary to an abnormal closure of the neural tube between third and fourth weeks of gestational ages. Neural tube defects affect birth outcomes worldwide, with an occurrence of 18.6 per 10,000 live births. In addition, neural tube defects are associated with considerable mortality, morbidity, disability, and socio-economical cost.

OBJECTIVE

To identify factors associated with neural tube defects among newborns delivered at Debre Berhan Comprehensive Specialized Hospital, 2021.

METHODS

Facility-based case-control study design was conducted among 381 (127 cases and 254 controls) newborns delivered from June 2019 to June 2021 at Debre Berhan Specialized Hospital. Consecutive and systematic random sampling techniques were used to select cases and controls, respectively. Data were collected using semi-structured checklists. Finally, data were entered using Epidata version 4.2.1 and analyzed using SPSS version 25. In the bivariable logistic regression model, factors with a p < 0.20 were entered into multivariable logistic regressions. Statistical significance was declared at a p < 0.05.

RESULT

In this study, 381 newborns (127 cases and 254 controls) participated with a response rate of 100%. In the logistic regression model, mothers who took medication during pregnancy [AOR 1.83 (95% CI 1.08-3.08)], mothers who did not take a balanced diet during pregnancy [AOR 13.46 (95% CI 7.83-23.13)], and mothers who did not take folic acid before and during the first trimester of pregnancy [AOR 1.71 (95% CI 1.01-2.94)] were significantly associated with neural tube defect.

CONCLUSION AND RECOMMENDATION

Mothers who took medication during pregnancy, mothers who did not take balanced diets during pregnancy, and mothers who did not take folic acid during pregnancy were the significant factors of neural tube defects. Health care professionals should focus on maternal safe drug prescription, maternal folate intake, and a balanced diet before and during pregnancy.

Parenteral Zinc Supplementation Increases Pregnancy Rates in Beef Cows

Zinc (Zn) is required for normal reproductive performance in cattle. The aim of this study was to evaluate the effect of subcutaneous injection of 400 mg Zn at the beginning of fixed-time artificial insemination (FTAI) on preovulatory follicle and corpus luteum (CL) size, plasma estradiol (E2) and progesterone (P4) concentrations, and pregnancy rates in beef cows. Copper (Cu) concentration and alkaline phosphatase (ALP) activity in plasma were also evaluated. Zinc supplementation at the beginning of the FTAI protocol (day 0) increased the area of preovulatory follicle (APF, day 9; P = 0.042) and plasma P4 concentration (day 16; P = 0.01), whereas plasma E2 concentration (day 9) and area of CL (ACL; day 16) were not modified by Zn supplementation in cows with adequate plasma Zn concentration. Zinc supplementation in Zn-deficient cows increased ACL with respect to controls (P = 0.048) but did not modify plasma E2 concentration. Pregnancy rate on day 41 after FTAI was higher in cows supplemented with Zn compared with controls (80.95% and 51.61%, respectively; P = 0.042). Plasma Zn and Cu concentrations on days 7, 9, and 16 were not affected by Zn supplementation. In conclusion, the results obtained in the present study determined that parenteral Zn supplementation at the beginning of the FTAI protocol increased preovulatory follicle size, plasma P4 concentration, and pregnancy rates in beef cows.

Use of Mango Mesocarp Flour to Enrich the Provitamin A Content of a Complementary Food Blend of Maize and Soya Bean Flours for Porridge

This study used locally available raw materials to enrich the contents of provitamin A (β-carotene) and other nutrients in a maize-based traditional complementary food for infants and pre-school children in Benue State, Nigeria. Fermented maize, dehulled soya bean, and sliced mango mesocarp were dried in a mobile wooden solar cabinet dryer (65°–70°C) to a moisture level of 8% to 10%. The dried products were milled separately. Blends containing different proportions of the flours were prepared to determine the most appropriate blend for preparing porridge, which was tested by sensory evaluation. The most appropriate blend consisted of 55% maize, 25% soya bean, and 20% mango flour (blend B). Its β-carotene content was 233 μg/100 g. The β-carotene contents of other blends were 199 μg/100g for 60% maize, 25% soya bean, and 15% mango (blend C), and 158 μg/100 g for 70% maize and 30% soya bean (blend A), whereas that of traditional maize akamu was 67 μg/100 g. The provitamin A retention percentages were 89% for blend A, 92% for blend B, 91% for blend C, and 88% for akamu. A healthy, well-fed infant 6 to 11 months of age is expected to consume 200 to 300 ml of the porridge, which provides 13 to 20 μg of retinol activity, compared with 1 to 2 μg of retinol activity expected from akamu. The porridge prepared with blend B was organoleptically acceptable. Detailed nutrient composition, including essential amino acids, was determined.

The Case for Promoting Multiple Vitamin And Mineral Supplements for Women of Reproductive Age in Developing Countries

Women in developing countries often consume inadequate amounts of micronutrients because of their limited intake of animal products, fruits, vegetables, and fortified foods. Intakes of micronutrients less than the recommended values increase a woman's risk of having micronutrient deficiencies. the adverse effects of deficiencies in vitamin A, iron, and folic acid, including night-blindness in pregnant and lactating women and iron-deficiency anaemia, are well known. Low intakes of these and other nutrients, including zinc, calcium, riboflavin, vitamin B6, and vitamin B12, also have consequences for women's health, pregnancy outcome, and the health and nutritional status of breastfed children. Multiple deficiencies coexist, so the benefit of multiple micronutrient supplements is becoming increasingly apparent. Supplementation of women with multiple vitamins and minerals should be one component of a strategy to improve micronutrient status among women in developing countries. However, there are several issues for programme managers to consider before implementing programmes. Which reference standards will be used to determine nutrient levels to include in the supplements? Which nutrients will be included and in what quantities? Which factors need to be considered in purchasing supplements? These issues are discussed, and guidance is provided on the selection of appropriate supplements for pregnant women and women of reproductive age in developing countries.

Association between Maternal Zinc Status, Dietary Zinc Intake and Pregnancy Complications: A Systematic Review

Adequate zinc stores in the body are extremely important during periods of accelerated growth. However, zinc deficiency is common in developing countries and low maternal circulating zinc concentrations have previously been associated with pregnancy complications. We reviewed current literature assessing circulating zinc and dietary zinc intake during pregnancy and the associations with preeclampsia (PE); spontaneous preterm birth (sPTB); low birthweight (LBW); and gestational diabetes (GDM). Searches of MEDLINE; CINAHL and Scopus databases identified 639 articles and 64 studies were reviewed. In 10 out of 16 studies a difference was reported with respect to circulating zinc between women who gave birth to a LBW infant (≤2500 g) and those who gave birth to an infant of adequate weight (>2500 g), particularly in populations where inadequate zinc intake is prevalent. In 16 of our 33 studies an association was found between hypertensive disorders of pregnancy and circulating zinc; particularly in women with severe PE (blood pressure ≥160/110 mmHg). No association between maternal zinc status and sPTB or GDM was seen; however; direct comparisons between the studies was difficult. Furthermore; only a small number of studies were based on women from populations where there is a high risk of zinc deficiency. Therefore; the link between maternal zinc status and pregnancy success in these populations cannot be established. Future studies should focus on those vulnerable to zinc deficiency and include dietary zinc intake as a measure of zinc status.

Environmental Risk Factors in the Etiology of Nonsyndromic Orofacial Clefts in the Western Region of Saudi Arabia

OBJECTIVES

Nonsyndromic orofacial cleft (NSOFC) etiology is multifactorial and heterogeneous. This study aimed to identify environmental risk factors related to NSOFC in the Western Region of Saudi Arabia.

METHODS

A case-control study carried out in seven hospitals in two main cities (Jeddah and Maddina) over 2 years on parents of 112 infants with NSOFC (infants were also examined) and 138 infant controls, matched for age (<18 months), gender, and location, completed a questionnaire on 3-month pregestation and first trimester events.

RESULTS

There was significantly increased NSOFC risk with twin pregnancies (P = .01, odds ratio [OR] = 9.5, 95% confidence interval [CI]: 1.15 to 78.4), maternal antibiotic use (P = .021, OR = 2.71, 95% CI: 1.11 to 6.62), antiemetic medication (P = .005, OR = 2.85, 95% CI: 1.3 to 6), severe morning sickness (P = .006, OR = 3.6, 95% CI: 1.34 to 9.65), illness (P = .009, OR = 2.19, 95% CI: 1.17 to 4.08), common cold/flu (P = .003, OR = 3.32, 95% CI: 1.48 to 7.58), Jorak smoking (P = .004, OR = 14.07, 95% CI: 1.55 to 128.1), and passive smoking (P = .05, OR = 2.05, 95% CI: 1.05 to 4.01). Reduced NSOFC risk was found with calcium supplementation (P = .02, OR = 0.32, 95% CI: 0.11 to 0.88), incense use (P = .03, OR = 0.58, 95% CI: 0.34 to 0.98), and maternal drinking water, with Zamzam water (which contains a high concentration of minerals) showing a significant protective effect compared with tap water (P = .01, 95% CI: 0.06 to 0.6) and bottled water (P = .02, 95% CI: 0.03 to 0.57).

CONCLUSION

Twin births, maternal antibiotic use, antiemetic medication, severe morning sickness, common cold/flu, Jorak smoking, and passive smoking were associated with infants born with NSOFC. Calcium supplementation, incense use, and Zamzam water reduced the risk of NSOFC, raising the possibility of community preventive programs.

Fluctuation of potential zinc status biomarkers throughout a reproductive cycle of primiparous and multiparous sows

Fluctuations in Zn metabolism throughout gestation and lactation might affect Zn requirements. However, scientific data on Zn requirements for breeding sows are limited. The objective of the present study was to assess the Zn status of primiparous and multiparous sows using different Zn status biomarkers, to identify periods of critical Zn status throughout the reproductive cycle at different parities. Blood samples were taken after overnight fasting before feeding in the morning from five primiparous and ten multiparous sows at fixed time intervals during gestation (days - 5, 0 (insemination), 21, 42, 63 and 84), around parturition (days 108, 112, 115 (parturition) and 118) and during lactation (days 122, 129 and 143 (weaning)). At parturition, blood samples were collected from two randomly selected piglets per sow before colostrum intake. Plasma was analysed for Zn and Cu contents, whereas serum was analysed for alkaline phosphatase, metallothionein and albumin concentrations. Independently of parity, all biomarkers fluctuated differently during gestation and lactation (P< 0·050). This reflects their different roles in Zn metabolism, and suggests that the choice of a Zn status biomarker necessitates careful consideration. Low average plasma Zn concentration at the end of gestation and throughout lactation seem to be replenished towards weaning.

Vegetarian diets across the lifecycle: impact on zinc intake and status

Optimal zinc status is an important consideration when evaluating the nutritional adequacy of vegetarian diets. In the absence of animal tissue sources of zinc and with increased intake of inhibitors of zinc absorption, phytic acid in particular, the bioavailability of zinc is thought to be lower from vegetarian as compared to omnivorous diets. The aim of this chapter is to review the research that examines the effects of vegetarian compared to omnivorous diets on zinc intake and zinc status in the elderly, adults, children, pregnancy, and lactation. A narrative review of the published literature was undertaken, focusing on observational studies in humans that reported zinc intake and biomarkers of zinc status at various stages of the life cycle. Compared to their respective nonvegetarian control groups, adult male and female vegetarians have lower dietary zinc intakes and serum zinc concentrations. However in the elderly, children, and in women during pregnancy and lactation, there is insufficient evidence to determine whether zinc intake and status are lower in vegetarians compared to omnivores. Inconsistencies in study findings reflect variations inherent in the definition of vegetarian diets, and in many instances compromised statistical power due to a small sample size. Improved methods for the assessment of zinc status are required to determine whether homeostatic responses are sufficient to maintain an adequate zinc status in vegetarians, particularly during times of increased requirement. Appropriate dietary advice to increase the zinc content and bioavailability of vegetarian diets throughout the life cycle is prudent.

Relationships of maternal zinc intake from animal foods with fetal growth

Zn is an essential element for human growth. The nutritional adequacy of dietary Zn depends not only on the total Zn intake, but also on the type of food source (i.e. of plant or animal origin). We investigated the association between maternal dietary Zn intake from animal and plant food sources and fetal growth. A total of 918 pregnant women at 12-28 weeks of gestation were selected from the Mothers and Children's Environmental Health study in Korea. Dietary intakes in mid-pregnancy were estimated by a 24 h recall method, and subsequent birth weight and height were obtained from medical records. Multiple regression analysis showed that maternal Zn intake from animal food sources and their proportions relative to total Zn intake were positively associated with birth weight (P = 0.034 and 0.045, respectively) and height (P = 0.020 and 0.032, respectively). Conversely, the percentage of Zn intake from plant food sources relative to total Zn intake was negatively associated with birth height (P = 0.026) after adjustment for covariates that may affect fetal growth. The molar ratio of phytate:Zn was negatively associated with birth weight (P = 0.037). In conclusion, we found that the absolute amounts of Zn from different food sources (e.g. animal or plant) and their proportions relative to total Zn intake were significantly associated with birth weight and height. A sufficient amount of Zn intake from animal food sources of a relatively higher Zn bioavailability is thus encouraged for women during pregnancy.

The potential of rice to offer solutions for malnutrition and chronic diseases

It is internationally accepted that malnutrition and chronic diseases in developing countries are key limitations to achieving the Millennium Development Goals. In many developing countries, rice is the primary source of nutrition. In those countries, the major forms of malnutrition are Fe-induced anaemia, Zn deficiency and Vitamin A deficiency, whereas the major chronic disease challenges are Type II diabetes, cardiovascular disease and some cancers. There is a growing corpus of evidence regarding both limitations and opportunities as to how rice could be an effective vehicle by which to tackle key nutrition and health related problems in countries with limited resources. Rice breeding programs are able to focus on developing new varieties carrying enhanced amounts of either Fe, Zn or beta-carotene because of large public investment, and the intuitive link between providing a mineral/vitamin to cure a deficiency in that mineral/vitamin. By contrast, there has been little investment in progressing the development of particular varieties for potential impact on chronic diseases. In this review article we focus on the broad battery of evidence linking rice-related nutritional limitations to their impact on a variety of human health issues. We discuss how rice might offer sometimes even simple solutions to rectifying key problems through targeted biofortification strategies and finally, we draw attention to how recent technological (-omics) developments may facilitate untold new opportunities for more rapidly generating improved rice varieties specifically designed to meet the current and future nutritional needs of a rapidly expanding global population.

Maternal zinc intakes and homeostatic adjustments during pregnancy and lactation

Zinc plays critical roles during embryogenesis, fetal growth, and milk secretion, which increase the zinc need for pregnancy and lactation. Increased needs can be met by increasing the dietary zinc intake, along with making homeostatic adjustments in zinc utilization. Potential homeostatic adjustments include changes in circulating zinc, increased zinc absorption, decreased zinc losses, and changes in whole body zinc kinetics. Although severe zinc deficiency during pregnancy has devastating effects, systematic reviews and meta-analysis of the effect of maternal zinc supplementation on pregnancy outcomes have consistently shown a limited benefit. We hypothesize, therefore, that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and, therefore, mitigate immediate detrimental effects due to a low zinc intake. The specific questions addressed are the following: How is zinc utilization altered during pregnancy and lactation? Are those homeostatic adjustments influenced by maternal zinc status, dietary zinc, or zinc supplementation? These questions are addressed by critically reviewing results from published human studies on zinc homeostasis during pregnancy and lactation carried out in different populations worldwide.

Relationship between Low Birth Weight Neonate and Maternal Serum Zinc Concentration

BACKGROUND

Zinc deficiency can lead to clinically relevant disturbances in tissue functions and particularly important for birth weight of neonates. The aim of this study was to determine the relationship between serum zinc in pregnant women and the incidence of low birth weight (<2500 g) in their newborns.

METHODS

This case-control study was done on women who delivered low birth weight infants (Cases), and normal birth weight infants (Controls). Blood samples got in all women within 5 minutes of delivery, and assessed the concentration of zinc using electrothermal atomic absorption spectrometry. Serum concentration of zinc was compared.

RESULTS

One hundred and seventeen mothers were enrolled, of them, 65 cases were low birth weight infants (1845±472 g) and 52 were controls (3166± 435 g). Mothers in the case and control groups did not differ in age, body mass index, and socioeconomic or demographic factors. Maternal zinc concentration differed between cases and controls; 753.34±15 µg/l vs. 654.76±12 µg/l respectively. Maternal zinc differed between premature and full term deliveries.

CONCLUSION

Maternal zinc concentration was shown to affect birth weight and prematurity.

Impact of maternal zinc status on fetal growth in an Iranian pregnant population

BACKGROUND

To evaluate the impact of mild to moderate maternal zinc deficiency on birth weight of offsprings in a group of Iranian pregnant population.

MATERIALS AND METHODS

One hundred forty pregnant subjects with no history of medical complications during pregnancy and without any inter-current illness enrolled in the study. Serum zinc concentration, ferritin, hemoglobin, iron, and total iron binding capacity (TIBC) were measured at the time of delivery. The receiver operator characteristic (ROC) curve analysis used to determine plasma zinc cutoff value for comparison.

RESULTS

Of 140 live neonates, 30% were below 2500 g. Mean serum zinc concentration was 56.60 ± 17.91 μg/dl which indicated mild to moderate zinc deficiency. None of the subjects were anemic. There was an inverse statistically significant relationship between maternal serum zinc concentration and neonatal birth weight.

CONCLUSION

In this group of Iranian pregnant subjects with mild to moderate zinc deficiency, we observed no relationship between low maternal zinc status and low birth weight infants.

Anaemia, zinc and copper deficiencies among pregnant women in central Sudan

Anaemia is a widespread problem in many parts of the world especially in tropic areas. Among pregnant women, it has negative consequences on maternal and perinatal outcomes. A cross-sectional study was conducted to investigate the prevalence of anaemia, iron, zinc and copper deficiencies among pregnant women in Wad Medani hospital, central Sudan and to examine the relationship of these micronutrients with haemoglobin (Hb) levels. One hundred four (52.5%) out of 200 pregnant women had anaemia (Hb < 11 gm/dl) and 3 (1.5) % had severe anaemia (Hb < 7 gm/dl). Iron deficiency (S-ferritin < 15 µg/l), iron deficiency anaemia (<11 gm/dl and S-ferritin < 15 µg/l) were prevalent in 25 (12.5%) and 13 (6.5%) of these women, respectively. Ninety (45.0%) and eight (4.0%) of these women had zinc (<80 µg/ml) and copper (<80 µg/ml) deficiency, respectively. In 24 (12.0%) of these women, there were ≥2 deficiencies of these elements. S-copper was not [corrected] significantly lower in patients with anaemia. While age, parity, gestational age, ferritin, zinc and copper were not predictors for anaemia, women who practiced pica were at higher risk for anaemia (OR = 3.4, 95% CI = 1.4-7.9, P = 0.004). Gestational age was significantly inversely correlated with haemoglobin (r = 0.161, P = 0.03), S-ferritin (r = 0.285, P = 0.001) and S-zinc (r = 0.166, P = 0.02). Thus, dietary and supplement interventions are required to prevent and control anaemia in this setting. Further research is needed.

Syndromes, disorders and maternal risk factors associated with neural tube defects (VI)

Neural tube defects (NTDs) may be associated with syndromes, disorders, and maternal and fetal risk factors. This article provides a comprehensive review of the syndromes, disorders, and maternal and fetal risk factors associated with NTDs, including maternal fumonisin consumption, periconceptional zinc deficiency, parental occupational exposure and residential proximity to pesticides, lower socioeconomic status, fetal alcohol syndrome, mutations in the VANGL1 gene, human athymic Nude/SCID fetus, and single nucleotide polymorphism in the NOS3 gene. NTDs associated with these syndromes, disorders, and maternal and fetal risk factors are a rare but important cause of NTDs. The recurrence risk and the preventive effect of maternal folic acid intake in NTDs associated with syndromes, disorders and maternal risk factors may be different from those of nonsyndromic multifactorial NTDs. Perinatal diagnosis of NTDs should alert doctors to the syndromes, disorders, and maternal and fetal risk factors associated with NTDs, and prompt thorough etiologic investigation and genetic counseling.

Simulation model of the impact of biofortification on the absorption of adequate amounts of zinc and iron among Mexican women and preschool children

BACKGROUND

Biofortification is an agricultural process that attempts to increase the iron and zinc content of staple food crops. Improving the absorption of zinc and iron could contribute to reducing the high rates of deficiency of these micronutrients in developing-country settings.

OBJECTIVE

To simulate the effects of biofortification of staple food crops (maize, wheat, rice, and beans) on the absorption of zinc and iron among women and children in Mexico.

METHODS

We analyzed dietary data from the 1999 Mexican National Nutrition Survey. On the basis of the intake of the four staple food crops and the increase in zinc and iron content that could be achieved by conventional breeding in the short term, the prevalence of inadequacy in the amounts of absorbed zinc and iron was determined. The mean increase in the amounts of absorbed zinc and iron was compared according to rural and urban residence and according to region of the country.

RESULTS

In rural areas, simulated biofortification of maize resulted in a reduction in the prevalence of absorption of inadequate amounts of zinc of 47% in children and 56% in women but had no effect on the prevalence of absorption of inadequate amounts of iron. The increase in zinc absorption was greater in rural populations and in the Central and Southern regions (p < .05).

CONCLUSIONS

Biofortification of maize could significantly improve zinc absorption among children and women in Mexico living in areas most vulnerable to zinc deficiency. Studies of the biological impact of biofortified maize on zinc status are warranted.

Prevention of Preterm Birth

The preterm birth rate in the USA is nearing 13%. The recent rise has been attributed to increased indicated preterm births and multiple births following artificial conceptions. There are few obstetrical interventions that successfully delay or prevent spontaneous preterm birth or reduce the risk factors leading to indicated preterm birth. On the other hand, there are many strategies that have improved outcomes for those infants who are born preterm. These include the use of corticosteroids for fetal maturation and regionalization of perinatal care for high-risk mothers and their infants. Several interventions, including progesterone use and cerclage, demonstrate promise in reducing spontaneous preterm births. The most pressing need is to better define the populations of pregnant women for whom these and other interventions will effectively reduce preterm birth.

Inadequate intakes of dietary zinc among pregnant women from subsistence households in Sidama, Southern Ethiopia

Objective

To assess the prevalence of zinc inadequacy based on dietary intakes and plasma zinc concentrations and, simultaneously, the prevalence of inadequate intakes of energy, protein, calcium and iron.

Design

A cross-sectional study of a convenience sample of subsistence farming households in Sidama, Southern Ethiopia.

Subjects

Dietary intakes were calculated from 1-day weighed food records and 40 repeats from 99 pregnant women in the third trimester using analysed values of major staple foods for zinc, iron, calcium and phytate. The distribution of observed intakes was adjusted for usual intakes and the prevalence of inadequacy estimated using the estimated average requirement (EAR) cutpoint method. Prevalence of inadequacy for zinc, protein and iron intakes were compared with those based on biochemical measures.

Results

Prevalence of zinc inadequacy was very high: 99% for US FNB EAR and 100% for IZiNCG EAR compared to 72% based on low plasma zinc concentrations. Corresponding prevalence estimates for iron were much lower: 4% for inadequate intakes based on US FNB EAR vs. 8.7% for iron deficiency anaemia (haemoglobin < 110 g l−1; ferritin < 12 μg l−1) and 32.3% for low storage iron. Prevalence of inadequacy for protein was 100% for adjusted intakes and 91% for serum albumin < 32 g l−1. For calcium, 74% were at risk for inadequate intakes.

Conclusion

The high prevalence of inadequate intakes of zinc and protein was reasonably consistent with those based on biochemical measures. Such dietary deficits could be overcome by regular consumption of cellular animal protein. In contrast, both dietary and biochemical measures of iron inadequacy were low.

Nutrition intervention strategies to combat zinc deficiency in developing countries

Widespread zinc deficiency is likely to exist in developing countries where staple diets are predominantly plant based and intakes of animal tissues are low. The severe negative consequences of zinc deficiency on human health in developing countries, however, have only recently been recognized. An integrated approach employing targeted supplementation, fortification and dietary strategies must be used to maximize the likelihood of eliminating zinc deficiency at a national level in developing countries. Supplementation is appropriate only for populations whose zinc status must be improved over a relatively short time period, and when requirements cannot be met from habitual dietary sources. As well, the health system must be capable of providing consistent supply, distribution, delivery and consumption of the zinc supplement to the targeted groups. Uncertainties still exist about the type, frequency, and level of supplemental zinc required for prevention and treatment of zinc deficiency. Salts that are readily absorbed and at levels that will not induce antagonistic nutrient interactions must be used. At a national level, fortification with multiple micronutrients could be a cost effective method for improving micronutrient status, including zinc, provided that a suitable food vehicle which is centrally processed is available. Alternatively, fortification could be targeted for certain high risk groups (e.g. complementary foods for infants). Efforts should be made to develop protected fortificants for zinc, so that potent inhibitors of zinc absorption (e.g. phytate) present either in the food vehicle and/or indigenous meals do not compromise zinc absorption. Fortification does not require any changes in the existing food beliefs and practices for the consumer and, unlike supplementation, does not impose a burden on the health sector. A quality assurance programme is required, however, to ensure the quality of the fortified food product from production to consumption. In the future, dietary modification/diversification, although long term, may be the preferred strategy because it is more sustainable, economically feasible, culturally acceptable, and equitable, and can be used to alleviate several micronutrient deficiencies simultaneously, without danger of inducing antagonistic micronutrient interactions. Appropriate dietary strategies include consumption of zinc-dense foods and those known to enhance zinc absorption, reducing the phytic acid content of plant based staplesviaenzymic hydrolysis induced by germination/fermentation or nonenzymic hydrolysis by soaking or thermal processing. All the strategies outlined above should be integrated with ongoing national food, nutrition and health education programmes, to enhance their effectiveness and sustainability, and implemented using nutrition education and social marketing techniques. Ultimately the success of any approach for combating zinc deficiency depends on strong advocacy, top level commitment, a stable infrastructure, long term financial support and the capacity to control quality and monitor and enforce compliance at the national or regional level. To be cost effective, costs for these strategies must be shared by industry, government, donors and consumers.

The effects of iron supplementation on serum copper and zinc levels in pregnant women with high-normal hemoglobin

OBJECTIVE

To evaluate the effect of iron supplementation on serum copper and zinc levels.

METHOD

In a randomized, double-blind, placebo-controlled trial, 66 pregnant women with hemoglobin 13.2 g/dL or greater between the 13th and 18th week of pregnancy were randomized into case and control groups. From the 20th week until the end of pregnancy the case group received one ferrous sulfate tablet containing 50 mg elemental iron daily, while the control group received placebo. Hemoglobin, ferritin, copper, and zinc levels at 24-28 and 32-36 weeks of pregnancy were measured and compared.

RESULTS

In the case group, serum copper levels in the second and third trimester were significantly lower than the control group (P<0.01 and P<0.001, respectively). Serum zinc levels in the case group in the second and third trimester were also significantly lower than the control group (P<0.001).

CONCLUSION

Iron supplementation in pregnant women with hemoglobin greater than 13.2 g/dL reduces serum levels of copper and zinc.

Relationship between pre-pregnancy BMI and plasma zinc concentrations in early pregnancy

We previously reported that pregnant women whose plasma Zn concentrations were below the 50th percentile tended to have high pre-pregnancy BMI (kg/m2) values. We therefore hypothesized that in pregnant women, plasma Zn concentrations are negatively correlated with BMI. We evaluated the association between BMI values and plasma Zn concentrations in 1474 women whose blood samples were obtained before 15 weeks of gestation. Their mean age was 22·7 years and mean gestational age at blood sampling was 10 weeks. The mean plasma Zn concentration and BMI were 11·6 μmol/l and 26·6 kg/m2 respectively. Because plasma Zn concentrations decrease as gestational age increases, plasma Zn concentrations were standardized by Z-scores. Z-score distributions were compared among the quartiles of BMI. The highest BMI group had the lowest plasma Zn concentrations, whereas the lowest BMI group had the highest; the differences were significant between the BMI groups (P<0·0001). The interpretation of plasma Zn concentrations to assess Zn nutriture in pregnancy may be complicated not only by the well-established factor of gestational age at blood sampling, but also by a previously unrecognized factor, maternal BMI.

Zinc deficiency in pregnancy and fetal outcome

Maternal zinc deficiency during pregnancy has been related to adverse effects on progeny, and there are data showing that mild to moderate zinc deficiency (as assessed by available indicators) is quite common in the developing world. Observational data relating zinc deficiency to adverse fetal outcome have produced conflicting results, mainly because of the lack of a valid indicator of zinc deficiency in pregnancy. Studies of human pregnancy and zinc supplementation, including those from developing countries, have failed to document a consistent beneficial effect on fetal growth, duration of gestation, and early neonatal survival. Preliminary results from unpublished studies in developing countries have also proven to be discouraging. However, recent data and some preliminary findings indicate a beneficial effect of maternal zinc supplementation on neonatal immune status and infant morbidity from infectious diseases, and there is also preliminary evidence that, zinc supplementation may prevent congenital malformations (cleft lip/palate). With respect to neurobehavioral development, the evidence is conflicting, with only one study reporting a positive outcome. More research is required to assess the benefits of the large-scale introduction of zinc supplementation during pregnancy on congenital malformations, immune functions, neurobehavior, and overall neonatal survival in countries where zinc deficiency is a problem. Currently available information does not support the routine use of zinc supplementation to improve pregnancy outcome.

Zinc supplementation to HIV-1-infected pregnant women: effects on maternal anthropometry, viral load, and early mother-to-child transmission

OBJECTIVE

To examine the effect of zinc supplementation to HIV-1-infected pregnant women on viral load, early mother-to-child transmission of HIV (MTCT), and wasting.

DESIGN

Double-blind placebo-controlled randomized clinical trial.

SETTING

Antenatal clinic in Dar es Salaam, Tanzania.

SUBJECTS

Four hundred HIV-1-infected pregnant women.

METHODS

Women 12-27 weeks of gestation were randomly assigned to receive a daily oral dose of 25 mg zinc or placebo from the day of the first prenatal visit until 6 weeks postdelivery. Weight and mid-upper arm circumference (MUAC) were measured monthly. HIV status of the babies was assessed at birth and at 6 weeks postpartum. Viral load was assessed in a random sample of 100 women at baseline and at the end of the study.

RESULTS

Zinc had no effects on maternal viral load or early MTCT. Supplementation was related to a significant threefold increase in the risk of wasting (reaching a MUAC value <22 cm) during an average 22 weeks of observation (RR=2.7, 95%CI=1.1, 6.4, P=0.03), and to a 4 mm decline in MUAC during the second trimester (P=0.02).

CONCLUSIONS

Zinc supplementation to HIV-infected pregnant women offers no benefits on viral load or MTCT. The clinical relevance of an apparent decrease in MUAC associated with zinc supplementation is yet to be ascertained. These findings together with the lack of effect on fetal outcomes (reported previously) do not provide support for the addition of zinc supplements to the standard of prenatal care among HIV-infected women.

Plasma zinc concentrations of mothers and the risk of nonsyndromic oral clefts in their children: a case-control study in the Philippines

BACKGROUND

Findings from animal experiments suggest a link between poor maternal zinc status and increased risk of oral clefts in offspring; however, there are few human studies on this issue.

METHODS

A case-control study was conducted using 74 case mothers of children with nonsyndromic cleft lip with or without cleft palate (CL/P, n=57) or cleft palate alone (CP, n=17), and 283 control mothers of unaffected children recruited in the Philippines in early 2003. Maternal zinc status was assessed by determining plasma zinc concentrations a mean of 5 years after delivery of the index child. Odds ratios (ORs) of estimates of the relative risk of oral clefts were calculated for quartiles of maternal plasma zinc concentrations.

RESULTS

The mean plasma zinc concentration of CL/P case mothers (9.6+/-1.2, SD micromol/l) was significantly lower than that in control mothers (10.1+/-1.6 micromol/l; P<0.05). Low plasma zinc concentrations (<11.0 micromol/l) were found in 88% and 94% of CL/P and CP case mothers, respectively, and in 72% of controls (P<0.05). The ORs for CL/P and CP combined, adjusted for potential confounding factors, decreased with increasing quartile of plasma zinc as follows: 1.0 (lowest quartile reference), 0.83 (95% confidence interval 0.37-1.89), 0.70 (0.31-1.68), and 0.26 (0.10-0.70) (P trend=0.008).

CONCLUSIONS

Low plasma zinc concentrations were common in Filipino women of reproductive age, and higher plasma zinc concentrations were associated with a lower risk for oral clefts in their children.

Trial of zinc supplements in relation to pregnancy outcomes, hematologic indicators, and T cell counts among HIV-1-infected women in Tanzania

BACKGROUND

In observational studies, the zinc status of HIV-infected persons has been associated with both positive and adverse clinical outcomes. Such endpoints may affect the risk of adverse birth outcomes among HIV-infected women.

OBJECTIVE

We examined the effects of zinc supplements on birth outcomes, hematologic indicators, and counts of T lymphocyte subsets among 400 HIV-infected pregnant women.

DESIGN

Eligible women between 12 and 27 wk of gestation were randomly assigned to daily oral supplementation with either 25 mg Zn or placebo between recruitment and 6 wk after delivery. All women received iron, folic acid, and multivitamin supplements irrespective of the experimental assignment.

RESULTS

We observed no significant differences in birth weight, duration of gestation, or fetal and neonatal mortality between women in the zinc and placebo groups. Hemoglobin concentrations increased between baseline and 6 wk postpartum in both groups. However, the rise in hemoglobin over this period was significantly lower (P = 0.03) in the zinc group (x +/- SD: 11.5 +/- 17.9 g/L) than in the placebo group (15.2 +/- 18.6 g/L). Similarly, the changes in red blood cell count and in packed cell volume over the same period were significantly lower in the zinc group (P < 0.01 and P = 0.01, respectively). Zinc had no effect on CD4(+), CD8(+), or CD3(+) cell counts during the follow-up period.

CONCLUSION

Because of the lack of beneficial effects of zinc on adverse pregnancy outcomes and the likelihood of negative effects on hemoglobin concentrations, no compelling evidence exists to support the addition of zinc to prenatal supplements intended for pregnant HIV-infected women.

Myo-inositol, glucose and zinc status as risk factors for non-syndromic cleft lip with or without cleft palate in offspring: a case-control study

OBJECTIVE

To investigate myo-inositol, glucose and zinc status in mothers and their infants on cleft lip with or without cleft palate risk (CLP).

DESIGN

Case-control study.

SETTING

University Medical Centre Nijmegen, the Netherlands.

POPULATION

Eighty-four mothers and their CLP child and 102 mothers and their healthy child.

METHODS

Venous blood samples were obtained to determine serum myo-inositol and glucose and red blood cell zinc concentrations in mothers and children. Geometric means were calculated and compared between the groups. The blood parameters were dichotomised with cutoff points based on control values, <P10 for myo-inositol and zinc concentrations and >P90 for glucose concentrations.

MAIN OUTCOME MEASURES

Geometric means (P5-P95) and odds ratios (95% confidence intervals).

RESULTS

The CLP children (P= 0.003) and their mothers (P= 0.02) had significantly lower red blood cell zinc concentrations than controls. A low maternal serum myo-inositol concentration (<13.5 micromol/L) and a low red blood cell zinc concentration (<189 micromol/L) increased CLP risk [odds ratio 3.0 (95% CI 1.2-7.4) and 2.0 (95% CI 0.8-4.8), respectively]. Children with low myo-inositol (<21.5 micromol/L ) or low red blood cell zinc concentrations (<118 micromol/L) were more likely to have CLP [odds ratio 3.4 (95% CI 1.3-8.6) and 3.3 (95% CI 1.3-8.0), respectively]. Glucose was not a risk factor for CLP in mothers and children. Maternal and child myo-inositol as well as zinc concentrations were slightly, albeit significantly correlated, r(Pearson)= 0.33 (P= 0.0006) and r(Pearson)= 0.23 (P= 0.01), respectively.

CONCLUSION

This study demonstrates for the first time that zinc and myo-inositol are important in the aetiology of CLP.

Effect of zinc supplementation of pregnant women on the mental and psychomotor development of their children at 5 y of age

BACKGROUND

A negative effect of prenatal zinc deficiency on brain function has been well established in experimental animals, but this association in humans is controversial.

OBJECTIVE

We evaluated the effect of prenatal zinc supplementation on the mental and psychomotor development of 355 children whose mothers participated in a double-blind trial of zinc supplementation that resulted in increased head circumference and birth weight.

DESIGN

The children took 6 tests-the Differential Ability Scales, Visual Sequential Memory, Auditory Sequential Memory, Knox Cube, Gross Motor Scale, and Grooved Pegboard tests-at a mean age of 5.3 y. The scores were compared between the children of women who received a daily oral dose of 25 mg Zn during the second half of pregnancy and the children of women who received placebo.

RESULTS

There were no differences in the test scores of neurologic development between the 2 groups. We analyzed the scores in 4 subgroups on the basis of maternal body mass index, because the increases in birth weight and head circumference due to the supplementation occurred only in the children of women with a body mass index (in kg/m(2)) < 26.0 in the original trial. No differences in the scores were found between these subgroups.

CONCLUSIONS

Zinc supplementation of women in the latter half of pregnancy had no effect on the neurologic development of their children at age 5 y. It is not known whether our findings of no positive effect in the population with apparently inadequate zinc nutriture can be readily extrapolated to other populations.

The plausibility of micronutrient deficiency in relationship to perinatal infection

Infection has a major effect on adverse pregnancy outcomes, and this relationship appears strongest among populations that suffer from malnutrition. The most likely mediating factor linking this association is the effect of nutritional status on various host defense mechanisms. These mechanisms include intact skin and epithelial surfaces, phagocytosis by macrophages and neutrophils, cell-mediated protection by T cells and natural killer cells and antibody production by B cells. Deficiencies of virtually every vitamin and mineral and protein-energy malnutrition have been shown to negatively affect some or several host defense functions. There is therefore no question that a plausible relationship exists between micronutrient deficiency and infection-mediated adverse pregnancy outcomes. However, proof of this relationship is generally not available.

Zinc supplementation might potentiate the effect of vitamin A in restoring night vision in pregnant Nepalese women

BACKGROUND

Zinc deficiency may result in abnormal dark adaptation or night blindness, a symptom primarily of vitamin A deficiency. During a placebo-controlled trial in Nepal, weekly vitamin A supplementation of women reduced but failed to eliminate the incidence of night blindness during pregnancy, suggesting a role for zinc.

OBJECTIVE

The study examined the efficacy of daily zinc supplementation in restoring night vision of pregnant women who developed night blindness while routinely receiving either vitamin A, beta-carotene, or placebo in a field trial.

DESIGN

Women (n = 202) who reported to be night blind during pregnancy were randomly assigned in a double-blind manner, stratified on vitamin A, beta-carotene, or placebo receipt, to receive 25 mg Zn or placebo daily for 3 wk. Thus, the 6 groups studied were as follows: beta-carotene + zinc, beta-carotene alone, vitamin A + zinc, vitamin A alone (vitamin A + placebo), zinc alone (zinc + placebo), and placebo (2 placebos: one for the vitamin A or beta-carotene study and one for the zinc study). Women underwent a clinic-based assessment that included pupillary threshold testing and phlebotomy before and after supplementation. Supplement use and daily history of night blindness were obtained at home twice every week.

RESULTS

Zinc treatment increased serum zinc concentrations, but alone (zinc alone group), failed to restore night vision or to improve dark adaptation. However, women in the vitamin A + zinc group who had baseline serum zinc concentrations <9.9 micromol/L were 4 times more likely to have their night vision restored (95% CI: 1.1, 17.3) than were women in the placebo group and tended to have a small improvement in pupillary threshold scores (by 0.21 log candela/m2; P = 0.09).

CONCLUSION

These data suggest that zinc potentiated the effect of vitamin A in restoring night vision among night-blind pregnant women with low initial serum zinc concentrations.

Effect of gestational zinc deficiency on pregnancy outcomes: summary of observation studies and zinc supplementation trials

The lack of a valid indicator precludes a true estimate of zinc deficiency in pregnancy in various populations. However, it is possible that mild to moderate deficiency (as assessed by available indicators) may be common in the developing world. Animal experiments indicate that zinc deficiency can result in adverse maternal and fetal consequences. Human data, particularly from prenatal zinc supplementation trials, has failed to document a consistent maternal or infant benefit on evaluated outcome measures including pregnancy induced hypertension, preterm/post-term labour, premature rupture of membranes, maternal infection, postpartum haemorrhage, perinatal mortality, congenital malformations and fetal growth and gestation. Preliminary data suggest a beneficial effect of prenatal zinc supplementation on infants' neurobehavioural development and immune function (evaluated by diarrhoeal and ARI morbidity incidence in the first year of life). Future research should focus on these functional consequences and congenital malformations (with adequate sample sizes), and simultaneously address the safety issue, particularly in relation to micronutrient interactions. In the light of the currently available information, routine zinc supplementation can not be advocated to improve pregnancy outcome.

Inhibition of zinc absorption by iron depends on their ratio

Previous studies upon zinc-iron interactions gave conflicting results that could come from differences in protocol design or in trace element status of subjects. The present work assessed the influence of zinc : iron ratio and iron deficiency upon zinc absorption. The digestive absorption of zinc sulphate (100 micromol Zn/l) in presence of iron gluconate was studied in perfused jejunal loops (n = 6/group) of normal rats (range 0-1000 micromol Fe/l) and iron deficient rats (200-750 micromol Fe/l). In normal rats no significant iron inhibition on zinc absorption occurred at Fe:Zn ratio below 2:1. At higher ratios zinc uptake and net absorption decreased significantly (p<0.05). Between 2:1 and 5:1 a dose dependent inhibition of zinc absorption occurred and reached a plateau beyond this ratio. In iron deficient animals no changes in zinc uptake, mucosal retention and absorption compared to normal animals occurred at ratio 2:1. At higher ratios differences were observed at every zinc absorption step except for mucosal retention at 7.5:1 ratio. Iron-zinc interactions depend on their ratio and on previous trace elements status of subjects. Due to the wide and unknown variations that were likely to occur between the subjects of previous human and experimental studies, these results could explain some of the discrepancies between their results.

Spina bifida and other neural tube defects

NTDs, resulting from failure of the neural tube to close during the fourth week of embryogenesis, are the most common severely disabling birth defects in the United States, with a frequency of approximately 1 of every 2000 births. Neural tube malformations involving the spinal cord and vertebral arches are referred to as spina bifida, with severe types of spina bifida involving protrusion of the spinal cord and/or meninges through a defect in the vertebral arch. Depending on the level of the lesion, interruption of the spinal cord at the site of the spina bifida defect causes paralysis of the legs, incontinence of urine and feces, anesthesia of the skin, and abnormalities of the hips, knees, and feet. Two additional abnormalities often seen in children with spina bifida include hydrocephalus and the Arnold-Chiari type II malformation. Despite the physical and particular learning disabilities children with spina bifida must cope with, participation in individualized educational programs can allow these children to develop skills necessary for autonomy in adulthood. Advances in research to uncover the molecular basis of NTDs is enhanced by knowledge of the link between both the environmental and genetic factors involved in the etiology of NTDs. The most recent development in NTD research for disease-causing genes is the discovery of a genetic link to the most well-known environmental cause of neural tube malformation, folate deficiency in pregnant women. Nearly a decade ago, periconceptional folic acid supplementation was proven to decrease both the recurrence and occurrence of NTDs. The study of folate and its association with NTDs is an ongoing endeavor that has led to numerous studies of different genes involved in the folate metabolism pathway, including the most commonly studied thermolabile mutation (C677T) in the MTHFR gene. An additional focus for NTD research involves mouse models that exhibit both naturally occurring NTDs, as well as those created by experimental design. We hope the search for genes involved in the risk and/or development of NTDs will lead to the development of strategies for prevention and treatment. The most recent achievement in treatment of NTDs involves the repair of meningomyelocele through advancements in fetal surgery. Convincing experimental evidence exists that in utero repair preserves neurologic function, as well as resolving the hydrocephalus and Arnold-Chiari malformation that often accompany meningomyelocele defects. However, follow-up is needed to completely evaluate long-term neurologic function and overall improved quality of life. And in the words of Olutoye and Adzick, "until the benefits of fetal [meningomyelocele] repair are carefully elucidated, weighed against maternal and fetal risks, and compared to conventional postnatal therapy, this procedure should be restricted to a few centers that are committed (clinically and experimentally) to investigating these issues."

Prenatal iron supplements impair zinc absorption in pregnant Peruvian women

Prenatal iron supplements may adversely influence zinc absorption during pregnancy. To examine the impact of prenatal iron supplements on supplemental zinc absorption, fractional zinc absorption was measured in 47 pregnant Peruvian women during the third trimester of pregnancy (33 +/- 1 wk gestation). Of these 47 women, 30 received daily prenatal supplements from wk 10-24 of pregnancy until delivery. Supplements contained 60 mg of Fe and 250 microg of folate without [iron group (Fe), n = 16] or with [iron and zinc supplemented group (Fe + Zn), n = 14] 15 mg of Zn. The remaining 17 women [unsupplemented control group (C)] received no prenatal supplementation. Zinc concentrations were measured in plasma, urine and cord blood and percentage zinc absorption was determined following dosing with oral ((67)Zn) and intravenous ((70)Zn) stable zinc isotopes. Percentage zinc absorption was significantly lower than controls in fasting women receiving iron- containing prenatal supplements (20.5 +/- 6.4 vs. 20.2 +/- 4.6 vs. 47.0 +/- 12.6%, Fe, Fe + Zn and C groups, respectively, P: < 0.0001, n = 40). Plasma zinc concentrations were also significantly lower in the Fe group compared to the C group (8.2 +/- 2.2 vs. 9.2 +/- 2.2 vs. 10.9 +/- 1. 8 micromol/L, Fe, Fe + Zn and C groups, respectively, P: = 0.002), and cord zinc concentrations were significantly related to maternal plasma Zn levels (y = 6.383 + 0.555x, r = 0.486, P: = 0.002). The inclusion of zinc in prenatal supplements may reduce the potential for iron supplements to adversely influence zinc status in populations at risk for deficiency of both these nutrients.

Determinants of maternal zinc status during pregnancy

Zinc deficiency in pregnant experimental animals limits fetal growth and, if severe, causes teratogenic anomalies. Although the data from human studies are not consistent, similar outcomes have been observed and were associated with poor maternal zinc status. This paper reviews humans studies of zinc status and pregnancy outcome, describes the physiologic adjustments in zinc utilization during pregnancy to meet fetal needs while maintaining maternal status, and identifies dietary and environmental conditions that may override those physiologic adjustments and put the health of the mother and fetus at risk. Adjustments in intestinal zinc absorption appear to be the primary means by which zinc retention is increased to meet fetal demands. However, transfer of sufficient zinc to the fetus is dependent on maintenance of normal maternal serum zinc concentrations. Conditions that could interfere with zinc absorption include intake of cereal-based diets that are high in phytate, high intakes of supplemental iron, or any gastrointestinal disease. Conditions that may alter maternal plasma zinc concentrations and the transport of zinc to the fetus include smoking, alcohol abuse, and an acute stress response to infection or trauma. Supplemental zinc may be prudent for women with poor gastrointestinal function or with any of these conditions during pregnancy.