Dietary indicators for assessing the adequacy of population zinc intakes

Do Global Dietary Nutrient Datasets Associate with Human Biomarker Assessments? A Regression Analysis

BACKGROUND

To assess the state and trends of global nutrition, our best tools are nationally representative assessments using human biomarker assays, yet these are expensive and logistically challenging. We instead often rely on more easily produced global nutrient datasets-measures of nutrients provided by the diet-as a proxy for nutritional intake and deficiency, due to their greater geographic and temporal coverage. However, the accuracy of global nutrient datasets is questionable.

OBJECTIVE

We aimed to test whether estimates of inadequate dietary intake derived from existing global nutrient datasets reliably associate with biophysical deficiency.

DESIGN

We performed linear regressions of estimates of inadequate dietary nutrient intake derived from three global nutrient datasets-Global Dietary Database, Global Nutrient Database, and Global Expanded Nutrient Supply (GENuS) model-against the existing suite of nationally representative biomarker survey data for three key nutrients of global concern in two vulnerable demographic groups: zinc, folate, and vitamin A in females of childbearing age; and zinc and vitamin A in children younger than 5 y.

RESULTS

We found significant associations (P < 0.1) for only 3 of 22 regressions between global nutrition datasets and biophysical deficiency: zinc for females of childbearing age from GENuS and Global Dietary Database, and zinc for children under 5 y from GENuS. Folate and vitamin A show no reliable relationship between nutrient datasets and independent biomarker surveys. Applying the successful models for zinc to the accompanying full datasets yield estimates of global zinc deficiency of 31%-37% for these demographic groups.

CONCLUSIONS

We found that few estimates of nutritional inadequacy from global dietary datasets are associated with more direct measures of biophysical deficiency from biomarker studies. Researchers and policymakers must be cautious when applying global nutrient datasets to questions of global health and use them for limited applications.

Zinc Status and Autism Spectrum Disorder in Children and Adolescents: A Systematic Review

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder, the prevalence of which has increased in children and adolescents over the years. Studies point to deficiency of trace elements as one of the factors involved in the etiology of the disorder, with zinc being one of the main trace elements investigated in individuals with ASD. The aim of this review is to summarize scientific evidence about the relationship between zinc status and ASD in children and adolescents. This review has been registered in the International Prospective Register of Systematic Reviews (registration number CRD42020157907). The methodological guidelines adopted were in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Studies were selected from an active investigation of the PubMed, Scopus, LILACS, and Google databases to search for observational studies. Fifty-two studies from twenty-two countries were included. The sample sizes ranged from 20 to 2635, and the participants ranged from 2 to 18 years old. Nine types of biological matrices were used, with hair, serum, and plasma being the most frequently used in the evaluation of zinc concentrations. Significant differences in zinc concentrations between the ASD and control groups were observed in 23 studies, of which 19 (36%) showed lower zinc concentrations in the ASD group. The classification of studies according to methodological quality resulted in high, moderate, and low quality in 10, 21, and 21 studies, respectively. In general, we did not observe a significant difference between zinc concentrations of children and adolescents with ASD compared to controls; however, studies point to an occurrence of lower concentrations of Zn in individuals with ASD. This review reveals that more prospective studies with greater methodological rigor should be conducted in order to further characterize this relation.

Dietary practices and nutritional status of children served in a social program for surrogate mothers in Colombia

BACKGROUND

Dietary practices are acquired in the family context and in turn can affect the health of family members, especially the nutritional status of children. The objective of this study was to determine the relationship between nutritional status and feeding practices in children from foster families served by the SOS Children's Villages program in Cartagena, Colombia.

METHODS

The study had a cross-sectional design. Through a non-probabilistic purposive sampling, 139 children from 0 to 5 years of age from the SOS Children's Villages Cartagena program were involved. The sociodemographic background of the participants was recorded and the nutritional status of the children was evaluated through anthropometric and biochemical measurements. Dietary practices were measured by means of a standardized questionnaire. Analyses were performed with Poisson regression models with robust variance. These regression models provided prevalence ratios (PR) with their respective 95% confidence intervals (95%CI).

RESULTS

Among dietary practices, it was observed that most families eat together at home (63.3%), watch television when they eat (55.4%), and have dietary norms (80.6%). Consumption of plant foods was predominantly high, especially vegetables (86.3%), fruits (92.1%), cereals (84.9%), root vegetables, and bananas (93.5%). Consumption < 4 times/week of soft drinks and industrialized juices increases 14.3 times the probability of low weight-for-height in the study population compared to the group that does not consume them. On the other hand, watching television while eating (PR: 2.82, 95%CI 1.32-4.69) and consumption of sweet snacks (PR: 2.24, 95%CI 1.03-4.87) increased the probability of low height-for-age; while having eaten norms at home decreased the probability of low height-for-age in the study population by 50%.

CONCLUSION

It is necessary to develop and implement interventions such as preventive measures and early diagnosis of inappropriate feeding behaviors to ensure adequate nutritional status among children under 5 years of age.

Existing knowledge on Zn status biomarkers (1963-2021) with a particular focus on FADS1 and FADS2 diagnostic performance and recommendations for further research

The role of Zn in human health was discovered 60 years ago, and despite remarkable research efforts, a sufficiently sensitive and specific biomarker of Zn status is still lacking. Plasma/serum Zn, currently the best available and most accepted population Zn status indicator, responds well to severe Zn deficiency, yet, mild to moderate Zn deficiency states usually remain unrecognized. Identifying early-stage Zn deficiency requires additional robust markers of Zn status. This paper discusses the sensitivity, specificity, and responsiveness of plasma Zn concentrations to Zn interventions. It describes the biochemical and dietary basis for the causal association between Zn and fatty acid desaturases activity, FADS1 and FADS2, based on data collected through studies performed in animals and/or humans. The influence of potential confounders and covariates on the observed relationships is considered. Additional potential Zn biomarkers are discussed and suggestions for further research in this area are provided.

The Effect of Pumpkin Seed Biscuits on Nutritional and Zinc Status: A Randomized Controlled Trial in Pregnant Women

BACKGROUND: In several studies in Indonesia, low birth weight (LBW) is shown as the most dominant risk factor for stunting. Some of the causes of LBW are chronic energy deficiency during pregnancy, anemia during pregnancy, lack of nutrient supply during pregnancy, pregnancy complications, maternal parity, and birth spacing. In this case, women commonly suffer from micronutrient deficiencies including iodine, iron, Vitamin A, zinc, and folate. Related to this, about 80% of pregnant women in the world fulfill normative pregnancy needs due to inadequate zinc intake. One source of micronutrients rich in zinc is pumpkin seeds. The nutritional potential of pumpkin seeds is realized in the form of food products for pregnant women, including amino acids. One example of pumpkin seed fortification has been assessed in biscuit products by trained panelists and consumers, obtaining results that 20% additional pumpkin seed flour to biscuits becomes the best treatment. Meanwhile, in the case of this study, we expect that the pumpkin seed biscuits provided can increase the energy intake in pregnant women because when pumpkin seeds are added, the nutrition contained in the biscuits is also increased, in this case, the nutrition includes the zinc and Fe. AIM: The purpose this research is to figure out how pumpkin seed biscuits affect pregnant women concerning their nutrition status and serum zinc levels. METHODS: The method employed was a double-blind and randomized experimental research involving pre- and post-test control groups. The inclusion criteria of the participants involved were pregnant women aged 20–35 years old who were at their first and second trimesters of pregnancy and parity one to three and singleton pregnancy. Meanwhile, the exclusion criteria of the participants were pregnant women suffering from severe complications. There were 89 pregnant women further gathered in this study, but only 66 of them met the criteria and idled into two groups. In this case, one group received the pumpkin seed biscuit intervention, while the other received placebo biscuits. The intervention was conducted for 90 days where the pregnant women were provided with four biscuits for daily consumption. RESULTS: The nutritional status parameter of pregnant women involved in the current research was assessed, including body weight, mid-upper arm circumference (MUAC), and serum zinc levels. In this case, the average serum zinc level obtained was 48.75 g/dL from 60 pregnant women. Furthermore, a significant increase occurred in nutritional status for each group, marked by body weight gain, and increased MUAC. However, no significant difference emerged between the pumpkin seed biscuit group and the placebo biscuit group with p = 0.914 and p = 0.916, respectively. A significant increase in zinc levels was observed in both groups. In this case, changes in zinc levels between the two groups were significantly different (13.72 ± 1.84 vs. 9.81 ± 11.81, p = 0.007). CONCLUSION: Giving pumpkin seed biscuits contribute to weight gain and increase the MUAC the pregnant women which, in turn, improves their nutritional status and serum zinc.

A Tomato Pomace Enriched Gluten-Free Ready-to-Cook Snack’s Nutritional Profile, Quality, and Shelf Life Evaluation

Attempts were undertaken to design a quick ready-to-cook gluten-free snack utilizing finger millet and potato flour (50:50) as well as tomato pomace due to the restricted availability of gluten-free snack goods in the Indian market. The nutritional content of the food and its general acceptability, cooking characteristics, and storage stability were all tested. The addition of tomato pomace had a distinct influence on the product’s color and hardness. Additionally, it resulted in a significant reduction in the amount of oil used, cooking loss, and frying time required. With a high acceptance level, the snack supplemented with 10% tomato pomace was determined to be the most optimal formulation. When the same substance was subjected to FTIR analysis, it was discovered that it retained all the important functional groups required for sustaining antioxidant activity. It also displayed high storage stability, a desirable overall acceptance score, and a very promising nutritional profile, all of which would benefit the product’s end users.

Protocol for meta-research on the evidence informing micronutrient dietary reference intakes for pregnant and lactating women

Nutrient reference values are important parameters that guide nutrition and public health work globally. Micronutrient requirements during the peri-conception period are generally increased, which is essential in ensuring maternal, fetal, and neonatal health. Nevertheless, the current dietary reference intakes (DRIs) may be limited in terms of the methods used and the populations included, particularly the DRIs for pregnancy and lactation. In this proposed review, we will examine the methods (rigor of design, utilization of molecular methods, and presence of modern methods) and the population (inclusion of women, and in particular, pregnant and lactating people) in the studies used to inform the current DRIs. We will apply meta-science methods to this review, which involves formally reviewing the current evidence, and identifying opportunities to improve how we fund, perform, evaluate, and incorporate nutrition science into public health programs for better outcomes.

Association of maternal diet, micronutrient status, and milk volume with milk micronutrient concentrations in Indonesian mothers at 2 and 5 months postpartum

BACKGROUND

Maternal micronutrient deficits during preconception and pregnancy may persist during lactation and compromise human milk composition.

OBJECTIVE

We measured micronutrient concentrations in human milk and investigated their association with maternal micronutrient intakes, status, and milk volume.

METHODS

Infant milk intake (measured via a deuterium dose-to-mother technique), milk micronutrient and fat concentrations, and maternal micronutrient intakes were assessed at 2 and 5 mo postpartum in 212 Indonesian lactating mother-infant pairs. Maternal hemoglobin, ferritin, transferrin receptors, retinol binding protein (RBP), zinc, selenium, and vitamin B-12 were measured at 5 mo (n = 163). Multivariate or mixed effects regression examined associations of milk micronutrient concentrations with maternal micronutrient intakes, status, and milk volume.

RESULTS

Prevalence of anemia (15%), and iron (15% based on body iron), selenium (2.5%), and vitamin B-12 deficiency (0%) were low compared with deficiencies of zinc (60%) and vitamin A (34%). The prevalence of inadequate intakes was >50% for 7 micronutrients at 2 and 5 mo. Median milk concentrations for most micronutrients were below reference values, and nearly all declined between 2 and 5 mo postpartum and were not associated substantially with milk volume (except for β-carotene, α-carotene, and β-cryptoxanthin). At 5 mo postpartum, associations between maternal micronutrient status and corresponding milk concentrations reported as mean percentage difference in human milk concentration for each unit higher maternal biomarker were significant for hemoglobin (1.9%), iron biomarkers (ranging from 0.4 to 7%), RBP (35%), selenium (70%), and vitamin B-12 (0.1%), yet for maternal intakes only a positive association with β-carotene existed.

CONCLUSIONS

Most milk micronutrient concentrations declined during lactation, independent of changes in human milk production, and few were associated with maternal micronutrient intakes. The significant associations between maternal biomarkers and milk micronutrient concentrations at 5 mo warrant further study to investigate whether the declines in milk micronutrients are linked to shifts in maternal status.

Equity implications of rice fortification: a modelling study from Nepal

Objective:

To model the potential impact and equity impact of fortifying rice on nutritional adequacy of different subpopulations in Nepal.

Design:

Using 24-h dietary recall data and a household consumption survey, we estimated: rice intakes; probability of adequacy (PA) of eight micronutrients commonly fortified in rice (vitamin A, niacin (B₃), pyridoxine (B₆), cobalamin (B₁₂), thiamin (B₁), folate (B₉), Fe and Zn) plus riboflavin (B₂), vitamin C and Ca and mean probability of adequacy (MPA) of these micronutrients. We modelled: no fortification; fortification of purchased rice, averaged across all households and in rice-buying households only. We compared adequacy increases between population subgroups.

Setting:

(i) Dhanusha and Mahottari districts of Nepal (24-h recall) and (ii) all agro-ecological zones of Nepal (consumption data).

Participants:

(i) Pregnant women (n 128), mothers-in-law and male household heads; (ii) households (n 4360).

Results:

Unfortified diets were especially inadequate in vitamins B₁₂, A, B_9, Zn and Fe. Fortification of purchased rice in rice-purchasing households increased PA > 0·9 for thiamin, niacin, B₆, folate and Zn, but B₁₂ and Fe remained inadequate even after fortification (PA range 0·3–0·9). Pregnant women’s increases exceeded men’s for thiamin, niacin, B₆, folate and MPA; men had larger gains in vitamin A, B₁₂ and Zn. Adequacy improved more in the hills (coefficient 0·08 (95 % CI 0·05, 0·10)) and mountains (coefficient 0·07 (95 % CI 0·01, 0·14)) but less in rural areas (coefficient −0·05 (95 % CI −0·09, −0·01)).

Conclusions:

Consumption of purchased fortified rice improves adequacy and gender equity of nutrient intake, especially in non-rice-growing areas.

Biofortified Crops for Combating Hidden Hunger in South Africa: Availability, Acceptability, Micronutrient Retention and Bioavailability

In many poorer parts of the world, biofortification is a strategy that increases the concentration of target nutrients in staple food crops, mainly by genetic manipulation, to alleviate prevalent nutrient deficiencies. We reviewed the (i) prevalence of vitamin A, iron (Fe) and zinc (Zn) deficiencies; (ii) availability of vitamin A, iron and Zn biofortified crops, and their acceptability in South Africa. The incidence of vitamin A and iron deficiency among children below five years old is 43.6% and 11%, respectively, while the risk of Zn deficiency is 45.3% among children aged 1 to 9 years. Despite several strategies being implemented to address the problem, including supplementation and commercial fortification, the prevalence of micronutrient deficiencies is still high. Biofortification has resulted in the large-scale availability of βcarotene-rich orange-fleshed sweet potatoes (OFSP), while provitamin A biofortified maize and Zn and/or iron biofortified common beans are at development stages. Agronomic biofortification is being investigated to enhance yields and concentrations of target nutrients in crops grown in agriculturally marginal environments. The consumer acceptability of OFSP and provitamin A biofortified maize were higher among children compared to adults. Accelerating the development of other biofortified staple crops to increase their availability, especially to the target population groups, is essential. Nutrition education should be integrated with community health programmes to improve the consumption of the biofortified crops, coupled with further research to develop suitable recipes/formulations for biofortified foods.

Micronutrient intakes of lactating mothers and their association with breast milk concentrations and micronutrient adequacy of exclusively breastfed Indonesian infants

BACKGROUND

Breast milk is the sole source of nutrition for exclusively breastfed infants in the first 6 mo of life, yet few studies have measured micronutrient concentrations in breast milk in light of maternal diet and subsequent infant micronutrient intakes.

OBJECTIVES

We evaluated the adequacy of micronutrient intakes of exclusively breastfed Indonesian infants by measuring milk volume and micronutrient concentrations and assessed maternal micronutrient intakes and their relationship with milk concentrations.

METHODS

Mother-infant (2-5.3 mo) dyads (n = 113) were recruited for this cross-sectional study. Volume of breast-milk intake via the deuterium dose-to-mother technique over 14 d and analyzed micronutrient concentrations were used to calculate micronutrient intakes of exclusively breastfed infants. Maternal 3-d weighed food records were collected to assess median (IQR) micronutrient intakes. Multivariate regression analyses examined the association of usual maternal micronutrient intakes with milk micronutrient concentrations after adjustment for confounding variables.

RESULTS

Mean ± SD intake of breast-milk volume was 787 ± 148 mL/d. Median daily infant intakes of iron, zinc, selenium, magnesium, sodium, and B-vitamins (thiamin, riboflavin, niacin, pantothenic acid, B-6, and B-12) were below their respective Adequate Intakes. Inadequacies in maternal intakes (as % < estimated average requirements) were >40% for calcium, niacin, and vitamins A, B-6, and B-12. Significant positive associations existed between maternal usual intakes of vitamin A, niacin and riboflavin and milk retinol, nicotinamide, and free riboflavin concentrations in both unadjusted and adjusted (for infant age, milk volume, and parity) analyses (all P < 0.05).

CONCLUSIONS

The majority of micronutrient intakes for these exclusively breastfed infants and their mothers fell below recommendations, with associations between maternal intakes and breast-milk concentrations for 3 nutrients. Data on nutrient requirements of exclusively breastfed infants are limited, and a better understanding of the influence of maternal nutritional status on milk nutrient concentrations and its impact on the breastfed infant is needed.

Maternal Selenium, Copper and Zinc Concentrations in Early Pregnancy, and the Association with Fertility

Trace elements such as zinc, copper, and selenium are essential for reproductive health, but there is limited work examining how circulating trace elements may associate with fertility in humans. The aim of this study was to determine the association between maternal plasma concentrations of zinc, copper, and selenium, and time to pregnancy and subfertility. Australian women (n = 1060) who participated in the multi-centre prospective Screening for Pregnancy Endpoints study were included. Maternal plasma concentrations of copper, zinc and selenium were assessed at 15 ± 1 weeks' gestation. Estimates of retrospectively reported time to pregnancy were documented as number of months to conceive; subfertility was defined as taking more than 12 months to conceive. A range of maternal and paternal adjustments were included. Women who had lower zinc (time ratio, 1.20 (0.99-1.44)) or who had lower selenium concentrations (1.19 (1.01-1.40)) had a longer time to pregnancy, equivalent to a median difference in time to pregnancy of around 0.6 months. Women with low selenium concentrations were also at a 1.46 (1.06-2.03) greater relative risk for subfertility compared to women with higher selenium concentrations. There were no associations between copper and time to pregnancy or subfertility. Lower selenium and zinc trace element concentrations, which likely reflect lower dietary intakes, associate with a longer time to pregnancy. Further research supporting our work is required, which may inform recommendations to increase maternal trace element intake in women planning a pregnancy.

Hidden hunger in South Asia: a review of recent trends and persistent challenges

‘Hidden hunger’ is a term used to describe human deficiencies of key vitamins and minerals, also known as micronutrients. While global in scale, the prevalence of micronutrient deficiencies is particularly high in South Asia despite recent successes in economic growth, agricultural output and health care. The present paper reviews the most recent evidence on patterns and trends of hidden hunger across the region, with a focus on the most significant deficiencies – iodine, Fe, vitamin A and Zn – and interprets these in terms of health and economic consequences. The challenge for South Asian policy makers is to invest in actions that can cost-effectively resolve chronic nutrient gaps facing millions of households. Appropriate solutions are available today, so governments should build on evidence-based successes that combine targeted health system delivery of quality services with carefully designed multisector actions that help promote healthier diets, reduce poverty and ensure social protection simultaneously.

Iron, zinc, vitamin A and selenium status in a cohort of Indonesian infants after adjusting for inflammation using several different approaches

Inflammation confounds the interpretation of several micronutrient biomarkers resulting in estimates that may not reflect the true burden of deficiency. We aimed to assess and compare the micronutrient status of a cohort of Indonesian infants (n 230) at aged 6, 9 and 12 months by ignoring inflammation (unadjusted) and adjusting four micronutrient biomarkers for inflammation with C-reactive protein (CRP) and α-1-glycoprotein (AGP) using the following methods: (1) arithmetic correction factors with the use of a four-stage inflammation model; and (2) regression modelling. Prevalence of infants with any inflammation (CRP>5 mg/l and/or AGP>1 g/l) was about 25% at each age. Compared with unadjusted values, regression adjustment at 6, 9 and 12 months generated the lowest (P50 % across all ages. In conclusion, without inflammation adjustment, Fe deficiency was grossly under-estimated and vitamin A and Zn deficiency over-estimated, highlighting the importance of correcting for the influence of such, before implementing programmes to alleviate micronutrient malnutrition. However, further work is needed to validate the proposed approaches with a particular focus on assessing the influence of varying degrees of inflammation (i.e. recurrent acute infections and low-grade chronic inflammation) on each affected nutrient biomarker.

The influence of food consumption and socio-economic factors on the relationship between zinc and iron intake and status in a healthy population

OBJECTIVE

To examine Zn and Fe nutritional status of a healthy population by means of anthropometric, dietary and biochemical measurements and to investigate the relationship of usual Zn and Fe dietary intakes to Zn and Fe status. In addition, to examine the impact of food choices and socio-economic factors on Fe and Zn dietary intakes and status with the aim to identify groups at risk of dietary deficiency and suggest factors that may influence the status of these nutrients.

DESIGN

Food consumption was assessed by 24 h recall questionnaires. Twenty biochemical parameters were measured, of which Hb, haematocrit, erythrocyte count and plasma concentrations of Fe and Zn were directly related to Fe and Zn nutrition. The prevalence of study participants with inadequate micronutrient intakes was calculated using the Estimated Average Requirement cut-point method.

SETTING

Serbia, Europe.

SUBJECTS

Apparently healthy adults (25-65 years of age).

RESULTS

Mean daily Zn and Fe intakes were 9·1 mg and 11·6 mg for males and 7·3 mg and 9·4 mg for females, respectively. Five per cent of the study population had inadequate dietary Fe intake and 15-25 % had inadequate Zn intake. Lower Hb concentrations were measured in women with lower Zn intakes. No differences in Fe and Zn intakes and status among various socio-economic groups were observed, except for Fe intake between the low-income and affluent groups.

CONCLUSIONS

Regular follow-ups are needed to ensure that potential deficiencies of Zn and Fe do get recognized and addressed in a timely manner.

Brazilian studies on zinc deficiency and supplementation: emphasis on children

Abstract Objectives: to review the literature of studies developed in Brazil on zinc deficiency and the effects of supplementation. Methods: a literature review based on bibliographic research was carried out in SciELO, LILACS and MEDLINE/PUBMED databases. A total of 133 studies on zinc deficiency and 116 on the effects of supplementation were identified. Thirty-two articles, 16 of which were observational and 16 interventional, were analyzed. Results: the studies focused mainly on children (75.0% of the observational and 81.25% of the experimental studies). Biochemical deficiency of zinc in children presented great variability, from 0.0% to 74.3%, with expressive prevalence in most studies. Dietary inadequacy among children presented variability from 16.6% to 46.0%. Five from seven studies showed a positive effect of zinc supplementation on micronutrient nutritional status. Conclusions: there is evidence of zinc deficiency in children as a public health problem, preventable through micronutrient supplementation.

Conclusions of the Joint WHO/UNICEF/IAEA/IZiNCG Interagency Meeting on Zinc Status Indicators

Zinc deficiency is an important cause of morbidity in developing countries, particularly among young children, yet little information is available on the global prevalence of zinc deficiency. A working group meeting was convened by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and the International Zinc Nutrition Consultative Group (IZiNCG) to review methods of assessing population zinc status and provide standard recommendations for the use of specific biochemical, dietary, and functional indicators of zinc status in populations. The recommended biochemical indicator is the prevalence of serum zinc concentration less than the age/sex/time of day-specific cutoffs; when the prevalence is greater than 20%, intervention to improve zinc status is recommended. For dietary indicators, the prevalence (or probability) of zinc intakes below the appropriate estimated average requirement (EAR) should be used, as determined from quantitative dietary intake assessments. Where the prevalence of inadequate intakes of zinc is greater than 25%, the risk of zinc deficiency is considered to be elevated. Previous studies indicate that stunted children respond to zinc supplementation with increased growth. When the prevalence of low height-for-age is 20% or more, the prevalence of zinc deficiency may also be elevated. Ideally, all three types of indicators would be used together to obtain the best estimate of the risk of zinc deficiency in a population and to identify specific subgroups with elevated risk. These recommended indicators should be applied for national assessment of zinc status and to indicate the need for zinc interventions. The prevalence of low serum zinc and inadequate zinc intakes may be used to evaluate their impact on the target population's zinc status.

Biological Status and Dietary Intakes of Iron, Zinc and Vitamin A among Women and Preschool Children in Rural Burkina Faso

BACKGROUND

Food-based approaches such as biofortification are meant to sustainably address micronutrient deficiencies in poor settings. Knowing more about micronutrient intakes and deficiencies is a prerequisite to designing and evaluating interventions.

OBJECTIVE

The objectives of the study were to assess biological status and dietary intakes of iron, zinc and vitamin A among women and children aged 36-59 months in rural Burkina Faso and to study relationships between intake and status to better inform future food-based interventions.

DESIGN

A cross-sectional survey was carried out in two rural provinces of Burkina Faso on a random cluster sample of 480 mother-child pairs. Dietary data was obtained by 24-hour recalls repeated on a random sub-selection of 37.5% of subjects to allow calculation of nutrient's probability of adequacy (PA). Biomarkers were measured on a sub-sample of 180 mother-child pairs. Blood samples were analyzed for hemoglobin, serum ferritin, soluble transferrin receptors (sTfR), C-reactive protein, alpha-1-glycoprotein, serum zinc concentration (SZnC) and retinol. For each micronutrient the relationship between biomarker and dietary intake was investigated by multiple linear regression models accounting for inflammatory biomarkers.

RESULTS

Mean PA for iron, zinc and vitamin A was 0.49, 0.87 and 0.21 among women and 0.61, 0.95 and 0.33 among children, respectively. Prevalence of anemia, corrected low serum ferritin and high sTfR was 37.6%, 4.0% and 77.5% among women and 72.1%, 1.5% and 87.6% among children, respectively. Prevalence of low SZnC and corrected low serum retinol was 39.4% and 12.0% among women and 63.7% and 24.8% among children, respectively. There was a tendency for a positive relationship between vitamin A intakes and serum retinol among women (β = 0.0003, P = 0.06). Otherwise, no link was found between micronutrients biomarkers and intakes.

CONCLUSION

Our study depicted different images of micronutrient deficiencies when based on dietary intakes or biomarkers results, thus highlighting the need for more suitable biomarkers and more precise measures of absorbable micronutrient intakes at the individual level. It thus points to challenges in the design and evaluation of future biofortification or other food-based interventions in rural areas of Burkina Faso.

Serum zinc reference intervals and its relationship with dietary, functional, and biochemical indicators in 6- to 9-year-old healthy children

BACKGROUND

Zinc is an important cause of morbidity, particularly among young children. The dietary, functional, and biochemical indicators should be used to assess zinc status and to indicate the need for zinc interventions.

OBJECTIVE

The purpose of this study was to determine the zinc status and reference intervals for serum zinc concentration considering dietary, functional, and biochemical indicators in apparently healthy children in the Northeast Region of Brazil.

DESIGN

The cross-sectional study included 131 healthy children: 72 girls and 59 boys, aged between 6 and 9 years. Anthropometric assessment was made by body mass index (BMI) and age; dietary assessment by prospective 3-day food register, and an evaluation of total proteins was performed. Zinc in the serum samples was analyzed in triplicate in the same assay flame, using atomic absorption spectrophotometry.

RESULTS

With respect to dietary assessment, only the intake of fiber and calcium was below the recommendations by age and gender. All subjects were eutrophic according to BMI and age classification. Zinc intake correlated with energy (p=0.0019), protein (p=0.0054), fat (p<0.0001), carbohydrate (p=0.0305), fiber (p=0.0465), calcium (p=0.0006), and iron (p=0.0003) intakes. Serum zinc correlated with protein intake (p=0.0145) and serum albumin (p=0.0141), globulin (p=0.0041), and albumin/globulin ratio (p=0.0043). Biochemical parameters were all within the normal reference range. Reference intervals for basal serum zinc concentration were 0.70-1.14 µg/mL in boys, 0.73-1.17 µg/mL in girls, and 0.72-1.15 µg/mL in the total population.

CONCLUSIONS

This study presents pediatric reference intervals for serum zinc concentration, considering dietary, functional, and biochemical indicators, which are useful to establish the zinc status in specific groups. In this regard, there are few studies in the literature conducted under these conditions, which make it an innovative methodology.

Prediction of Serum Zinc Levels in Mexican Children at 2 Years of Age Using a Food Frequency Questionnaire and Different Zinc Bioavailability Criteria

BACKGROUND

The 2006 Mexican National Health and Nutrition Survey documented a prevalence of zinc deficiency of almost 30% in children under 2 years of age.

OBJECTIVE

We sought to validate a food frequency questionnaire (FFQ) for quantifying dietary bioavailable zinc intake in 2-year-old Mexican children accounting for phytic acid intake and using serum zinc as a reference.

METHODS

This cross-sectional study was nested within a longitudinal birth cohort of 333 young children in Mexico City. Nonfasting serum zinc concentration was measured and dietary zinc intake was calculated on the basis of a semiquantitative FFQ administered to their mothers. The relationship between dietary zinc intake and serum zinc was assessed using linear regression, adjusting for phytic acid intake, and analyzed according to two distinct international criteria to estimate bioavailable zinc. Models were stratified by zinc deficiency status.

RESULTS

Dietary zinc, adjusted for phytic acid intake, explained the greatest proportion of the variance of serum zinc. For each milligram of dietary zinc intake, serum zinc increased on average by 0.95 μg/dL (0.15 μmol/L) (p = .06). When stratified by zinc status, this increase was 0.74 μg/dL (p = .12) for each milligram of zinc consumed among children with adequate serum zinc (n = 276), whereas among those children with zinc deficiency (n = 57), serum zinc increased by only 0.11 μg/dL (p = .82).

CONCLUSIONS

A semiquantitative FFQ can be used for predicting serum zinc in relation to dietary intake in young children, particularly among those who are zinc-replete, and when phytic acid or phytate intake is considered. Future studies should be conducted accounting for both zinc status and dietary zinc inhibitors to further elucidate and validate these findings.

Zinc Deficiency in Latin America and the Caribbean

BACKGROUND

Zinc deficiency affects multiple vital functions in the life cycle, especially growth. Limited information is available on the magnitude of zinc deficiency in Latin America and the Caribbean.

OBJECTIVE

To examine the latest available information on both the prevalence of zinc deficiency and the risk of zinc deficiency in Latin America and the Caribbean.

METHODS

The prevalence of zinc deficiency was identified through a systematic review looking for the latest available data on serum zinc concentrations from surveys or studies with national representativeness conducted in Latin America and the Caribbean. The risk of zinc deficiency in Latin America and the Caribbean was estimated based on dietary zinc inadequacy (according to the 2011 National Food Balance Sheets) and stunting in children under 5 years of age.

RESULTS

Only four countries had available national biochemical data. Mexican, Colombian, Ecuadorian, and Guatemalan children under 6 years of age and women 12 to 49 years of age had a high prevalence of zinc deficiency (19.1% to 56.3%). The countries with the highest risk of zinc deficiency (estimated prevalence of inadequate zinc intake > 25% plus prevalence of stunting > 20%) were Belize, Bolivia, El Salvador, Guatemala, Haiti, Honduras, Nicaragua, and Saint Vincent and the Grenadines. Zinc dietary inadequacy was directly correlated with stunting (r = 0.64, p < .001).

CONCLUSIONS

Prevalence data from the four available Latin America and Caribbean national surveys indicate a high prevalence of zinc deficiency in children under 6 years of age and women 12 to 49 years of age. High rates of both estimated zinc dietary inadequacy and stunting were also reported in most Latin America and Caribbean countries.

Zinc-containing yeast extract promotes nonrapid eye movement sleep in mice

Zinc is an essential trace element for humans and animals, being located, among other places, in the synaptic vesicles of cortical glutamatergic neurons and hippocampal mossy fibers in the brain. Extracellular zinc has the potential to interact with and modulate many different synaptic targets, including glutamate and GABA receptors. Because of the central role of these neurotransmitters in brain activity, we examined in this study the sleep-promoting activity of zinc by monitoring locomotor activity and electroencephalogram after its administration to mice. Zinc-containing yeast extract (40 and 80 mg/kg) dose dependently increased the total amount of nonrapid eye movement sleep and decreased the locomotor activity. However, this preparation did not change the amount of rapid eye movement sleep or show any adverse effects such as rebound of insomnia during a period of 24 h following the induction of sleep; whereas the extracts containing other divalent cations (manganese, iron, and copper) did not decrease the locomotor activity. This is the first evidence that zinc can induce sleep. Our data open the way to new types of food supplements designed to improve sleep.

Differential Natural Selection of Human Zinc Transporter Genes between African and Non-African Populations

Zinc transporters play important roles in all eukaryotes by maintaining the rational zinc concentration in cells. However, the diversity of zinc transporter genes (ZTGs) remains poorly studied. Here, we investigated the genetic diversity of 24 human ZTGs based on the 1000 Genomes data. Some ZTGs show small population differences, such as SLC30A6 with a weighted-average FST (WA-FST = 0.015), while other ZTGs exhibit considerably large population differences, such as SLC30A9 (WA-FST = 0.284). Overall, ZTGs harbor many more highly population-differentiated variants compared with random genes. Intriguingly, we found that SLC30A9 was underlying natural selection in both East Asians (EAS) and Africans (AFR) but in different directions. Notably, a non-synonymous variant (rs1047626) in SLC30A9 is almost fixed with 96.4% A in EAS and 92% G in AFR, respectively. Consequently, there are two different functional haplotypes exhibiting dominant abundance in AFR and EAS, respectively. Furthermore, a strong correlation was observed between the haplotype frequencies of SLC30A9 and distributions of zinc contents in soils or crops. We speculate that the genetic differentiation of ZTGs could directly contribute to population heterogeneity in zinc transporting capabilities and local adaptations of human populations in regard to the local zinc state or diets, which have both evolutionary and medical implications.

Biomarkers of Nutrition for Development (BOND)-Zinc Review

Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole-body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND (Biomarkers of Nutrition for Development) Zinc Expert Panel recommends 3 measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole-body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using the PZC to assess zinc status. PZCs respond less to additional zinc provided in food than to a supplement administered between meals, there is considerable interindividual variability in PZCs with changes in dietary zinc, and PZCs are influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one that is recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information are the activity or amounts of zinc-dependent enzymes and proteins and biomarkers of oxidative stress, inflammation, or DNA damage.

Dietary and non-dietary factors associated with serum zinc in Indian women

Women in low-income settings, common in India, are at risk of inadequate zinc intake due to poor diet quality and low consumption of flesh foods rich in zinc. The aims of this study were to assess the prevalence of zinc status of non-pregnant rural and tribal women living in central India and to identify dietary and non-dietary factors associated with the biochemical zinc status of these women. Rural and tribal non-pregnant women 18-30 years of age were selected using proportion to population sampling near Nagpur, Maharashtra, India. Sociodemographic, biochemical (serum zinc), clinical, and dietary data (1-day interactive 24-h recall) were collected. The mean age of women (n = 109; rural = 52; tribal = 56) was 23.2 years and mean BMI was 17.9 kg/m(2). The majority of the participants identified as being non-vegetarian (72 %). The mean ± SD serum zinc concentration was 10.8 ± 1.6 μmol/L, and 52 % of participants had a low serum zinc concentration according to the International Zinc Nutrition Consultative Group (IZiNCG). The median (first and third quartile) energy, zinc intake, and phytate/zinc molar ratio was 5.4 (4.2, 6.7) MJ/day, 5.3 (3.8, 7.0) mg/day, and 26 (22, 28), respectively. Zinc intakes were well below IZiNCG recommendations for dietary zinc of 9 mg/day for non-pregnant women aged 14-18 years and 7 mg/day for non-pregnant women aged ≥ 19 years. Using linear regression analysis to identify non-dietary and dietary factors associated with serum zinc, a significant association was only found for current lactation (p = 0.012) and energy intake (p < 0.001). Diets low in energy with poor bioavailability of dietary zinc are likely to be the primary cause of the high proportion of Indian women with zinc deficiency.

Establishing desirable fortificant levels for calcium, iron and zinc in foods for infant and young child feeding: examples from three Asian countries

We used the World Health Organization's recommended procedures to establish desirable fortificant levels for three problem micronutrients in children's diets, based on dietary data collected earlier from Filipino (n = 1374; 6-36 months), Mongolian (n = 179; 12-36 months) and Cambodian (n = 177; 12-36 months) children. Prevalence of inadequate and excessive intakes of calcium and zinc (via cut-point method) and iron (via full-probability approach) was assessed after adjusting usual intake distributions with pc-side using internal or external within-person variances from Filipino (calcium and iron) and US National Health And Nutrition Examination Survey III (zinc) national surveys. Fortificant levels were determined by repositioning usual intake distributions so that the 2.5th percentile of the targeted populations equalled the estimated average requirement (calcium, zinc) or so that full-probability prevalence was no larger than 2.5% (iron). Prevalence of inadequate intakes was ≥70% for calcium and iron, except Filipino infants (30% for Ca) and Cambodian toddlers (41% for Fe); but <1% for zinc for toddlers in Mongolia and 20% in Cambodia. Prevalence of excessive intakes was <1% for zinc, calcium and iron, except for Mongolian toddlers (11% for Zn). Desirable fortificant levels, although apparently negligible for zinc, were 530-783 mg for calcium and 10.8-22.8 mg for iron (per 100 g). Fortificant levels can be estimated from 24-h recalls, preferably by applying internal within-person variances. Fortification with calcium and iron was necessary, but seemingly not for zinc, despite a high prevalence of low serum zinc, suggesting the need for better defined cut-offs for population risk of zinc deficiency based on dietary zinc intake and/or serum zinc.

Estimating the global prevalence of inadequate zinc intake from national food balance sheets: effects of methodological assumptions

Background

The prevalence of inadequate zinc intake in a population can be estimated by comparing the zinc content of the food supply with the population’s theoretical requirement for zinc. However, assumptions regarding the nutrient composition of foods, zinc requirements, and zinc absorption may affect prevalence estimates. These analyses were conducted to: (1) evaluate the effect of varying methodological assumptions on country-specific estimates of the prevalence of dietary zinc inadequacy and (2) generate a model considered to provide the best estimates.

Methodology and Principal Findings

National food balance data were obtained from the Food and Agriculture Organization of the United Nations. Zinc and phytate contents of these foods were estimated from three nutrient composition databases. Zinc absorption was predicted using a mathematical model (Miller equation). Theoretical mean daily per capita physiological and dietary requirements for zinc were calculated using recommendations from the Food and Nutrition Board of the Institute of Medicine and the International Zinc Nutrition Consultative Group. The estimated global prevalence of inadequate zinc intake varied between 12–66%, depending on which methodological assumptions were applied. However, country-specific rank order of the estimated prevalence of inadequate intake was conserved across all models (r = 0.57–0.99, P<0.01). A “best-estimate” model, comprised of zinc and phytate data from a composite nutrient database and IZiNCG physiological requirements for absorbed zinc, estimated the global prevalence of inadequate zinc intake to be 17.3%.

Conclusions and Significance

Given the multiple sources of uncertainty in this method, caution must be taken in the interpretation of the estimated prevalence figures. However, the results of all models indicate that inadequate zinc intake may be fairly common globally. Inferences regarding the relative likelihood of zinc deficiency as a public health problem in different countries can be drawn based on the country-specific rank order of estimated prevalence of inadequate zinc intake.

Estimating the global prevalence of zinc deficiency: results based on zinc availability in national food supplies and the prevalence of stunting

Background

Adequate zinc nutrition is essential for adequate growth, immunocompetence and neurobehavioral development, but limited information on population zinc status hinders the expansion of interventions to control zinc deficiency. The present analyses were conducted to: (1) estimate the country-specific prevalence of inadequate zinc intake; and (2) investigate relationships between country-specific estimated prevalence of dietary zinc inadequacy and dietary patterns and stunting prevalence.

Methodology and Principal Findings

National food balance sheet data were obtained from the Food and Agriculture Organization of the United Nations. Country-specific estimated prevalence of inadequate zinc intake were calculated based on the estimated absorbable zinc content of the national food supply, International Zinc Nutrition Consultative Group estimated physiological requirements for absorbed zinc, and demographic data obtained from United Nations estimates. Stunting data were obtained from a recent systematic analysis based on World Health Organization growth standards. An estimated 17.3% of the world’s population is at risk of inadequate zinc intake. Country-specific estimated prevalence of inadequate zinc intake was negatively correlated with the total energy and zinc contents of the national food supply and the percent of zinc obtained from animal source foods, and positively correlated with the phytate: zinc molar ratio of the food supply. The estimated prevalence of inadequate zinc intake was correlated with the prevalence of stunting (low height-for-age) in children under five years of age (r = 0.48, P<0.001).

Conclusions and Significance

These results, which indicate that inadequate dietary zinc intake may be fairly common, particularly in Sub-Saharan Africa and South Asia, allow inter-country comparisons regarding the relative likelihood of zinc deficiency as a public health problem. Data from these analyses should be used to determine the need for direct biochemical and dietary assessments of population zinc status, as part of nationally representative nutritional surveys targeting countries estimated to be at high risk.

Zinc modifies the effect of phyto-oestrogens on osteoblast and osteoclast differentiation in vitro

Osteoblast and osteoclast activity is disrupted in post-menopausal osteoporosis. Thus, to fully address this imbalance, therapies should reduce bone resorption and promote bone formation. Dietary factors such as phyto-oestrogens and Zn have beneficial effects on osteoblast and osteoclast activity. However, the effect of combinations of these factors has not been widely studied. We therefore examined the effect of coumestrol, daidzein and genistein in the presence or absence of zinc sulphate (Zn) on osteoclast and osteoblast activity. Osteoclast differentiation and bone resorption were significantly reduced by coumestrol (10- 7 m), daidzein (10- 5 m) and genistein (10- 7 m); and this direct anti-osteoclastic action was unaffected by Zn (10- 5 m). In addition, Zn augmented the inhibitory effect of phyto-oestrogens on the osteoblast-derived stimulus for osteoclast formation, significantly reducing the ratio of receptor activator of NF-κB ligand (RANKL)-to-osteoprotegerin mRNA expression in human osteoblast. We then examined the effect of these compounds on osteoblast activity. Mineralisation was enhanced by coumestrol (10- 5 to 10- 7 m), daidzein (10- 5 to 10- 6 m) and genistein (10- 5 m); and Zn significantly augmented this response. Zn and phyto-oestrogens also significantly enhanced alkaline phosphatase activity and Runt-related transcription factor 2 (Runx2) mRNA expression. On the other hand, Zn blunted phyto-oestrogen-induced type I collagen and osteocalcin expression and suppressed coumestrol and daidzein-stimulated osterix expression. Zn may therefore modify the anabolic action of phyto-oestrogens, promoting characteristics associated with early rather than late stages of osteoblast differentiation. Our data suggest that while Zn enhances the anti-osteoclastic effect of phyto-oestrogens, it may limit aspects of their anabolic action on bone matrix formation.

A historical review of progress in the assessment of dietary zinc intake as an indicator of population zinc status

Dietary components influencing zinc (Zn) bioavailability were implicated in the first cases of human Zn deficiency in the Middle East in the 1960s. It was not until the 1980s that isotope tracer studies in humans quantified the effects of the type and/or quantity of Zn, protein, iron, and phytate (myo-inositol hexaphosphate) on Zn absorption in humans and confirmed the dose-dependent inhibitory effect of phytate on Zn absorption. This led to further analysis of the Zn and phytate content of foods. The use of phytate-to-Zn molar ratios as likely estimates of absorbable dietary Zn followed together with an assessment of their relationship with Zn biomarkers in low-income countries (LIC). In the 1990s, increasing knowledge of factors governing Zn-absorption diets led to refinements of Zn requirements and algorithms to estimate dietary Zn bioavailability. Their use highlighted that inadequate Zn intake from plant-based diets were a major etiological factor in morbidity and stunting in LIC, prompting the need to identify indicators of the population's Zn status. Major advances in analyses of dietary data pioneered by Beaton in 1980s led to the endorsement in 2007 of a dietary Zn indicator based on the prevalence of the population with usual Zn intake below the estimated average requirement for Zn. Risk of Zn deficiency is a public health concern when the prevalence of inadequate Zn intake is >25%. Recent findings that Zn bioavailability from high-phytate, whole-day diets is lower than previous estimates suggest that revision of Zn estimated average requirement for LIC may be warranted.

Suboptimal dietary zinc intake promotes vascular inflammation and atherogenesis in a mouse model of atherosclerosis

SCOPE

Cardiovascular health is strongly influenced by diet. Zinc has antioxidant and anti-inflammatory properties but its long-term influence on vascular health at dietary intake levels relevant to the human population in developed countries has not been studied. We investigated the influence of suboptimal zinc intake in a Western-type diet on the development of vascular inflammation and arterial plaque in apoE knock-out (AEKO) mice.

METHODS AND RESULTS

Weanling AEKO and wild-type (WT) controls were given high saturated fat (21% w/w) and high cholesterol (0.15%) semi-synthetic diets containing 3 or 35 mg Zn/kg (AEKO and WT) or 8 mg Zn/kg (AEKO only) for over 6 months. AEKO mice on zinc intakes of 3 and 8 mg Zn/kg (suboptimal zinc) developed significantly (p < 0.05) more aortic plaque than AEKO mice consuming 35 mg Zn/kg (adequate zinc). Circulating levels of interleukin-1β, interleukin-6 and soluble vascular adhesion molecule-1 were significantly (p < 0.05) raised at the lowest zinc intake in AEKO mice, as compared to zinc-adequate controls. Plasma total cholesterol and total protein were also significantly (p < 0.05) increased at the lowest zinc intake.

CONCLUSION

We propose that suboptimal dietary zinc intake raises circulating pro-atherogenic lipoprotein levels that promote vascular inflammation and enhance arterial plaque formation.

Nutrient intakes and status of preschool children in Adelaide, South Australia

OBJECTIVE

To determine the nutrient intakes and status of preschool children from a representative population sample in Adelaide.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional survey of children aged 1-5 years, using a stratified random sampling method and a doorknocking strategy, between September 2005 and July 2007.

MAIN OUTCOME MEASURES

Dietary intake, assessed using a 3-day weighed-food diary; anthropometrics, biomarkers of iron, zinc and vitamin B(12), and fatty acid profiles assessed using standard methods.

RESULTS

Median energy intakes were within dietary recommendations for the age group. Overall energy contributions from carbohydrate, protein, fat and saturated fat intakes were 50%, 17%, 33% and 16%, respectively. The rates of inadequate intake of iron, zinc, calcium and vitamin C were low, as was the prevalence of iron deficiency (5%). Only a minority of children achieved the adequate intake for n-3 long-chain polyunsaturated fatty acids (32%) and dietary fibre (18%). There was no association between socioeconomic status and intakes of macronutrients and key micronutrients. Fourteen per cent of children were obese (BMI, > 95th percentile); no association between BMI and energy intake was shown.

CONCLUSIONS

The dietary intake of children in the study was adequate for macronutrients and the majority of micronutrients. However, low intakes of fibre and n-3 long-chain polyunsaturated fatty acids and high saturated fat intakes have raised concerns that this dietary pattern may be associated with adverse long-term health effects.

Zinc biofortification of rice in China: a simulation of zinc intake with different dietary patterns

A cross-sectional survey of 2819 adults aged 20 years and above was undertaken in 2002 in Jiangsu Province. Zinc intake was assessed using a consecutive 3-day 24-h dietary recall method. Insufficient and excess intake was determined according to the Chinese Dietary Recommended Intakes. Four distinct dietary patterns were identified namely "traditional", "macho", "sweet tooth", and "healthy". Intake of zinc from biofortified rice was simulated at an intermediate zinc concentration (2.7 mg/100 g) and a high zinc concentration (3.8 mg/100 g) in rice. Average total zinc intake was 12.0 ± 3.7 mg/day, and insufficiency of zinc intake was present in 15.4%. Simulated zinc intake from biofortified rice with intermediate and high zinc concentration decreased the prevalence of low zinc intake to 6.5% and 4.4%, respectively. The effect was most pronounced in the "traditional" pattern, with only 0.7% of insufficiency of zinc intake remaining in the highest quartile of the pattern. Zinc intake was inversely associated with the "sweet tooth" pattern. Zinc biofortifed rice improves dietary zinc intake and lowers risk for insufficient zinc intake, especially for subjects with a more "traditional" food pattern, but less for subjects with a "sweet tooth" food pattern.

Poor zinc status is associated with increased risk of insulin resistance in Spanish children

Zn plays a key role in the synthesis and action of insulin. The aim of the present work was to determine whether a poorer Zn status was associated with insulin resistance in a group of 357 Spanish schoolchildren. Zn intake was determined by using a 3 d food record (i.e. Sunday to Tuesday). The body weight, height and waist and hip circumferences of all subjects were recorded and fasting plasma glucose, insulin and Zn concentrations were determined. Insulin resistance was determined using the homoeostasis model assessment (HOMA) marker. Children (11·5 %) with Zn deficiency (serum Zn concentration < 10·7 μmol/l) had higher HOMA values than those with a more satisfactory Zn status (1·73 (sd0·93)) compared with 1·38 (sd0·90;P < 0·05). An inverse correlation was found between the HOMA value and the serum Zn concentration (r− 0·149,P < 0·05). The risk of having a greater insulin resistance value (HOMA greater than the 75th percentile) increased with age (OR 1·438; 95 % CI 1·021, 2·027) and BMI (OR 1·448; 95 % CI 1·294, 1·619) and decreased as Zn serum levels increased (OR 0·908; 95 % CI 0·835, 0·987;P < 0·001). Moreover, an inverse relationship was observed between HOMA values and Zn dietary density (r− 0·122), and the Zn intakes of male children with a HOMA value of >3·16 made a significantly smaller contribution to the coverage of those recommended (59·7 (sd14·7) %) than observed in children with lower HOMA values (73·6 (sd18·2) %;P < 0·05). Taking into account that Zn intake was below than that recommended in 89·4 % of the children, it would appear that increasing the intake of Zn could improve the health and nutritional status of these children, and thus contribute to diminish problems of insulin resistance.

Neonatal zinc supplementation for prevention of mortality and morbidity in breastfed low birth weight infants: systematic review of randomized controlled trials

OBJECTIVES

To evaluate whether zinc supplements prevent mortality and morbidity in breastfed low birth weight infants.

METHODS

All randomized or qausi-randomized trials with individual or cluster allocation and using concurrent controls were included. Study population included LBW infants irrespective of gestational status who were exclusively or predominantly breastfed at the initiation of intervention. Intervention comprised zinc salts given as tablets or syrups orally to provide at least 1 RDA of elemental zinc for at least a period of 14 days, introduced within one month of birth. Electronic databases were searched irrespective of language and publication status.

FINDINGS

Three trials from developing countries met the inclusion criteria. Limited data did not indicate a reduced risk of mortality (1 trial, RR=1.11; 95% CI 0.57 to 2.18 at one year), hospitalization rate (1 trial, odds ratio 1.10; 95% CI 0.87 to 1.39), acute respiratory infection (1 trial), or diarrhea (2 trials). However, the trial reporting on mortality was not adequately powered for evaluating this outcome. There was no evidence of an increase in weight (3 trials) or height (2 trials) at either 6 months or one year of age, or of an increased risk of vomiting following zinc supplementation. Serum zinc levels at the end of intervention were significantly higher in the supplemented group (2 trials).

CONCLUSIONS

In view of no convincing evidence of benefits from the limited data available, currently there is no justification for recommending routine zinc supplementation for breastfed LBW newborns in developing countries.

Accelerating improvements in nutritional and health status of young children in the Sahel region of Sub-Saharan Africa: review of international guidelines on infant and young child feeding and nutrition

The United Nations Convention on the Rights of the Child holds governments responsible to ensure children's right to the highest attainable standard of health by providing breastfeeding support, and access to nutritious foods, appropriate health care, and clean drinking water. International experts have identified key child care practices and programmatic activities that are proven to be effective at reducing infant and young child undernutrition, morbidity, and mortality. Nevertheless, progress towards reducing the prevalence of undernutrition has been sporadic across countries of the Sahel sub-region of Sub-Saharan Africa. In view of this uneven progress, a working group of international agencies was convened to 'Reposition children's right to adequate nutrition in the Sahel.' The first step towards this goal was to organize a situational analysis of the legislative, research, and programmatic activities related to infant and young child nutrition (IYCN) in six countries of the sub-region: Burkina Faso, Chad, Mali, Mauritania, Niger, and Senegal. The purposes of this introductory paper are to review current information concerning the nutritional and health status of infants and young children in the Sahel and to summarize international guidelines on optimal IYCN practices. These guidelines were used in completing the above-mentioned situational analyses and encompass specific recommendations on: (i) breastfeeding (introduction within the first hour after birth, exclusivity to 6 months, continuation to at least 24 months); (ii) complementary feeding (introduction at 6 months, use of nutrient dense foods, adequate frequency and consistency, and responsive feeding); (iii) prevention and/or treatment of micronutrient deficiencies (vitamin A, zinc, iron and anaemia, and iodine); (iv) prevention and/or treatment of acute malnutrition; (v) feeding practices adapted to the maternal situation to reduce mother-to-child transmission of HIV; (vi) activities to ensure food security; and (vii) the promotion of hygienic practices concerning food preparation and storage and environmental sanitation. The following papers in this issue will present results of the situational analyses for the individual countries.

Red meat and a fortified manufactured toddler milk drink increase dietary zinc intakes without affecting zinc status of New Zealand toddlers

Evidence suggests that New Zealand (NZ) children are mildly zinc deficient and may respond to dietary change. A 20-wk randomized intervention trial was therefore conducted to determine whether an increased intake of red meat or consumption of a fortified manufactured toddler milk drink (FTMD, fortified with zinc and other micronutrients) would increase dietary zinc intakes and improve the biochemical zinc status of 12- to 20-mo-old NZ toddlers. Toddlers were randomized to a red meat intervention (n = 90), FTMD intervention (n = 45), or nonfortified milk placebo (n = 90). Study foods were provided. Adherence was assessed via monthly 7-d meat or milk recording diaries. Hair and serum zinc concentrations, and length and weight were measured at baseline and postintervention. Nutrient intakes were assessed via 3-d weighed food records at baseline, wk 4, and wk 18. At baseline, 38% of participants had low serum zinc concentrations despite seemingly adequate dietary zinc intakes (<4% below the Estimated Average Requirement). Dietary zinc intakes significantly increased by 0.8 mg/d (95% CI: 0.5, 1.1) in the meat group and 0.7 mg/d (95% CI: 0.2, 1.1) in the FTMD group compared with a decrease of -0.5 (95% CI: -0.8, -0.2) mg/d in the placebo group. No corresponding increases in serum or hair zinc concentrations were observed. Dietary zinc intakes achievable via interventions based on red meat or a FTMD are unlikely to improve biochemical zinc status in NZ toddlers. These results also question cutoffs used to define zinc deficiency in toddlers.

Nutrient contribution of total and lean beef in diets of US children and adolescents: National Health and Nutrition Examination Survey 1999-2004

This study examined the nutritional contribution of total beef and lean beef (LB) to the diet of US children and adolescents using the US Department of Agriculture definition of LB as defined in MyPyramid. Twenty-four hour dietary recall data from children 4-8 years of age [y] (n=2474), 9-13 y (n=3273), and adolescents 14-18 y (n=4044) participating in the NHANES 1999-2004 were assessed. LB was defined as beef with ≤9.28 grams [g] fat/100 g (excess was discretionary fat). Means and standard errors were determined using appropriate sample weights. Consumption of LB contributed significantly to intake of protein and many key nutrients such as vitamins B6 and B12, zinc, iron, niacin, phosphorus, and potassium by US children and adolescents without providing significantly to intakes of total fat, saturated fatty acids, or sodium.

Higher risk of zinc deficiency in New Zealand Pacific school children compared with their Māori and European counterparts: a New Zealand national survey

Few multi-ethnic national surveys have examined Zn nutriture, despite its importance for optimal growth and development during childhood. We assessed the Zn status of urban and semi-urban children aged 5–15 years from three ethnic groups in New Zealand (NZ) in the 2002 Children's National Nutrition Survey and investigated the factors predisposing them to Zn deficiency. In a 10-month cross-sectional survey, Pacific and Māori children were over-sampled permitting ethnic-specific analyses. Anthropometry, serum Zn and Zn intakes via 24 h recalls were measured. Anthropometriczscores were highest in Pacific children. Overall, mean adjusted serum Zn at 11 years was for males and females, respectively: 11·9 (95 % CI 11·5, 12·3) and 12·5 (95 % CI 12·0, 12·9) μmol/l in NZ European and Other (NZEO) children (n395); 11·9 (95 % CI 11·4, 12·4) and 12·0 (95 % CI 11·4, 12·5) μmol/l in Māori children (n379); and 11·5 (95 % CI 11·1, 11·9) and 11·4 (95 % CI 11·1, 11·8) μmol/l in Pacific children (n589). The predictors of serum Zn were age, serum Se and sex for NZEO children; serum Se and age for Pacific children; and none for Māori children. Pacific children had the highest prevalence of low serum Zn (21 (95 % CI 11, 30) %), followed by Māori children (16 (95 % CI 12, 20) %) and NZEO children (15 (95 % CI 9, 21) %). Prevalence of inadequate Zn intakes, although low, reached 8 % for Pacific children who had the lowest Zn intake/kg body weight. Pacific boys but not girls with low serum Zn had a lower mean height-for-agez-score (P < 0·007) than those with normal serum Zn. We conclude that the biochemical risk of Zn deficiency in Pacific children indicates a public health problem. However, a lack of concordance with the risk of dietary Zn inadequacy suggests the need for better defined cut-offs in children.

Use of lipid-based nutrient supplements (LNS) to improve the nutrient adequacy of general food distribution rations for vulnerable sub-groups in emergency settings

The term 'lipid-based nutrient supplements' (LNS) refers generically to a range of fortified, lipid-based products, including products like Ready-to-Use Therapeutic Foods (RUTF) (a large daily ration with relatively low micronutrient concentration) as well as highly concentrated supplements (1-4 teaspoons/day, providing <100 kcal/day) to be used for 'point-of-use' fortification. RUTF have been successfully used for the management of severe acute malnutrition (SAM) among children in emergency settings. Recent research on smaller doses of LNS for prevention of malnutrition has created interest in their potential use in emergency settings to ensure a more nutritionally adequate ration for the most vulnerable groups [e.g. infants and children between 6 and 24 months of age, and pregnant and lactating women (PLW)]. Currently, the main food and nutrition interventions in emergency settings include general food distribution (GFD) rations, which are provided to the affected population as a whole, and selective (or supplementary) feeding programs (SFP), which are to be provided to nutritionally vulnerable or malnourished individuals. In addition to logistical and operational challenges that may limit the intended effect of these programs, the nutritional quality of the food commodities provided may be insufficient to meet the needs of infants and young children and PLW. Because these subgroups have particularly high nutrient needs for growth and development, meeting these needs is challenging in settings where the ration is limited to a few food commodities, with little access to a diverse diet and bioavailable sources of micronutrients. In recent years, there has been increased attention to adding micronutrient interventions, on top of the other food-based interventions (such as GFDs and SFPs), to fill micronutrient gaps in diets in emergency settings. The focus of this document is the potential role of LNS in meeting the nutritional needs of these vulnerable subgroups, with the goal of preventing malnutrition in emergency-affected populations. The document addresses the desired nutritional formulation of LNS for these target groups, taking into account the expected bioavailability of relevant nutrients and toxicity concerns. It also discusses the recommended chemical forms of the fortificants in LNS; stability and shelf-life considerations; production, packaging and distribution of LNS in the context of emergencies; and cost implications of the addition of LNS to current GFD rations for vulnerable groups. To develop the desired nutritional formulation of LNS for these purposes, we calculated the current nutrient content of commonly provided GFD rations and determined the nutritional 'gaps' (of both micro- and macronutrients) of these rations for each of the target groups (i.e. children 6-35 months of age and PLW). For fat and protein, both quantity and quality were evaluated. Through an iterative process, we determined the formulation of a small dose of LNS that would best meet the recommended nutrient intakes for each group in combination with other foods in the GFD ration [composed of a grain, pulse, oil, sugar and salt, but excluding a fortified blended food (FBF)], as well as breast milk for children 6-24 months of age, while avoiding excess levels of any one nutrient to the extent possible. The composition of the LNS used for these calculations is based on an existing LNS product (Nutributter, Malaunay, France, Nutriset), but with less sugar and more oil. Two different approaches were used: (1) developing two different formulations of LNS, one to be used for infants and children 6-35 months of age and a separate one for PLW; and (2) developing a single formulation that could be used for all of these subgroups. We used commodity cost data to estimate the cost of adding an LNS product to the GFD ration. The results indicate that the typical GFD ration currently provided in emergency settings--based on cereals, pulse, an FBF such as corn-soy blend (CSB), oil, salt and sugar-does not meet the nutritional needs of infants and young children and PLW. The hypothetical intake from a ration composed of food aid commodities (based on the current USAID/USDA specifications for exported food aid commodities used in emergency settings), and including breast milk for children 6-24 months of age, provided less than 75% of the recommended intake for several micronutrients for certain age/physiologic groups, including calcium, iron, zinc, B vitamins such as riboflavin, B6 and B12, and fat-soluble vitamins such as D, E and K. It also generally contained lower than recommended levels of fat and essential fatty acids. The initial LNS formulation for each target group was designed to provide 100% of the recommended amount (RDA or RNI) for most micronutrients per daily dose (20 g, approximately 118 kcal) of LNS. This would ensure consumption of the recommended levels of each nutrient even if the 'base' diet changed. However, because such a formulation could provide excess amounts of certain nutrients when consumed in combination with the 'base' diet (especially when the 'base' diet contains fortified foods), we made adjustments in the LNS formulation when there was a risk of greatly exceeding the Upper Level for certain subgroups and there were relevant concerns about adverse effects from chronic consumption of such amounts. For most nutrients, consumption of toxic amounts is highly unlikely with the proposed LNS formulations. The 'one-size' LNS formulation was designed so that one 'dose' (20 g) would be provided to infants and young children and two 'doses' (i.e. 40 g/day) would be provided to PLW. This 'one-size' formulation was based on the LNS formulation developed for children 6-35 months of age. Although the resulting formulation is not a perfect match for the unique nutritional needs of each subgroup, there are several practical advantages to using such an approach. As anticipated, addition of LNS to the GFD ration, even after eliminating the FBF (e.g. CSB), increases the cost. The 'revised' ration without CSB but with LNS would cost 34-52% more (food only) than the 'typical' GFD diet for a hypothetical mother-infant pair, depending on how many LNS 'doses' were provided to the mother. However, depending on the contribution of food costs to overall program costs, the overall increase in costs may be significantly less. Although cost is an important consideration, options to improve the nutritional quality of foods provided in emergency settings should also be assessed with regard to effectiveness in maintaining and improving nutritional outcomes. Another consideration is whether a specialized product like LNS is more easily targeted to the individuals for whom it is intended, thus reducing inter- and intra-household sharing, a common concern with other fortified products such as CSB. This could have substantial cost implications because programs usually compensate for sharing by inflating the amount of FBF provided. This document is intended to be a starting point for considering the incorporation of LNS in the food packages provided in emergency settings. Our goal was to examine the potential nutritional benefits but also the challenges of adopting such a strategy. There are many different options for emergency nutrition programs, and there are also many considerations governing which option to choose. This document is intended to encourage further evaluation of all of these options.

Recent advances in knowledge of zinc nutrition and human health

Zinc deficiency increases the risk and severity of a variety of infections, restricts physical growth, and affects specific outcomes of pregnancy. Global recognition of the importance of zinc nutrition in public health has expanded dramatically in recent years, and more experience has accumulated on the design and implementation of zinc intervention programs. Therefore, the Steering Committee of the International Zinc Nutrition Consultative Group (IZiNCG) completed a second IZiNCG technical document that reexamines the latest information on the intervention strategies that have been developed to enhance zinc nutrition and control zinc deficiency. In particular, the document reviews the current evidence regarding preventive zinc supplementation and the role of zinc as adjunctive therapy for selected infections, zinc fortification, and dietary diversification or modification strategies, including the promotion and protection of breastfeeding and biofortification. The purposes of this introductory paper are to summarize new guidelines on the assessment of population zinc status, as recommended by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and IZiNCG, and to provide an overview on several new advances in zinc metabolism. The following papers will then review the intervention strategies individually.

Indicators of zinc status at the population level: a review of the evidence

The role of zinc deficiency as an important cause of morbidity and impaired linear growth has prompted the need to identify indicators of population zinc status. Three indicators have been recommended - prevalence of zinc intakes below the estimated average requirement (EAR), percentage with low serum zinc concentrations, and percentage of children aged < 5 years who are stunted. This review outlines steps to estimate the prevalence of inadequate intakes, and confirm their validity based on the EARs set by International Zinc Nutrition Collaborative Group. Next, the appropriateness of serum zinc as a biochemical marker for population zinc status is confirmed by a summary of: (a) the response of serum zinc concentrations to zinc intakes; (b) usefulness of serum zinc concentrations to predict functional responses to zinc interventions; (c) relationship between initial serum zinc and change in serum zinc in response to interventions. Height- or length-for-age was chosen as the best functional outcome after considering the responses of growth, infectious diseases (diarrhoea, pneumonia), and developmental outcomes in zinc supplementation trials and correlation studies. The potential of other zinc biomarkers such as zinc concentrations in hair, cells, zinc-metalloenzymes, and zinc-binding proteins, such as metallothionein, is also discussed. Molecular techniques employing reverse transcriptase (RT)-polymerase chain reaction to measure mRNA in metallothionein and ZIP1 transporter hold promise, as do kinetic markers such as exchangeable zinc pools (EZP) and plasma zinc turnover rates. More research is needed to establish the validity, specificity, sensitivity, and feasibility of these new biomarkers, especially in community-settings.