Comparison of complementary feeding strategies to meet zinc requirements of older breastfed infants

Current Evidence on Nutrient Intakes and Infant Growth: A Narrative Review of Baby-Led Weaning vs. Conventional Weaning

Throughout infancy, changes in growth and development are observed, including changes in nutritional requirements; at approximately 6 months of age, when complementary feeding begins, breastmilk and/or formula are no longer the sole source of energy and nutrients. Little is known about the impact of complementary feeding (CF) approaches used during this time on infant nutrition and growth. Baby-led weaning (BLW) has continued to gain popularity over the last two decades, emphasizing the importance of examining the adequacy of different CF methods. This narrative review of 19 studies from January 2010 to April 2024 aims to discuss the differences between BLW and conventional weaning (CW). The definition of BLW varied across studies, and no standard definition has been established. Though no differences in energy were reported, macronutrient and micronutrient intakes were variable between approaches, including for micronutrients such as iron and zinc. Of the few studies with growth data, results comparing BLW and CW were conflicting. Differences were seen in the demographics of parents who chose to follow BLW and breastfeeding prevalence and duration prior to complementary feeding. Additional research is needed to understand the impacts of BLW and CW on nutrient intakes and growth to inform recommendations for infant complementary feeding approaches.

Benchmarking the nutrient composition and labelling practices of commercially produced ready-to-eat purées and meals for older infants and young children across seven Southeast Asian countries

Commercially produced complementary foods (CPCF), including ready-to-eat CPCF purées and meals, are gaining popularity among caregivers of older infants and young children (IYC) as a convenient alternative to home-prepared foods in low and middle-income countries. However, there is growing concern regarding the suitability of these products for older IYC, as they can contain high levels of sugar and/or sodium. Given the rapidly evolving market in Southeast Asia, it is crucial to monitor the appropriate composition and promotion of CPCF in the region. This study examined the nutrient composition and labelling practices of CPCF purées and meals sold in 2021 in the capital cities of seven Southeast Asian countries: Phnom Penh (Cambodia), Jakarta (Indonesia), Manila (Philippines), Bangkok (Thailand), Vientiane (Lao PDR), Hanoi (Viet Nam), Kuala Lumpur (Malaysia). The study adapted a nutrient profiling model from the WHO Regional Office for Europe to determine the proportion of products suitable for promotion for older IYC. The proportion of CPCF purées and meals that would require a high sugar front-of-pack warning based on the percentage energy from total sugar was also determined. Of the 459 CPCF purées/meals assessed, only 37.7% of the products met all nutrient composition requirements and none met all labelling requirements. In addition, most CPCF purées and meals were identified as having high total sugar content. To ensure that older IYC consume appropriate CPCF products, Southeast Asian countries need to implement and enforce regulations concerning the nutrient composition and labelling practices of CPCF purées and meals.

Toward revising dietary zinc recommendations for children aged 0 to 3 years: a systematic review and meta-analysis of zinc absorption, excretion, and requirements for growth

CONTEXT

The Food and Agriculture Organization of the United Nations and the World Health Organization are updating their dietary zinc recommendations for children aged 0 to 3 years.

OBJECTIVE

The aim of this review was to retrieve and synthesize evidence regarding zinc needs for growth as well as zinc losses, absorption, and bioavailability from the diet.

DATA SOURCES

MEDLINE, Embase, and Cochrane Library databases were searched electronically from inception to August 2020. Studies assessing the above factors in healthy children aged 0 to 9 years were included, with no limits on study design or language.

DATA EXTRACTION

Ninety-four studies reporting on zinc content in tissue (n = 27); zinc absorption (n = 47); factors affecting zinc bioavailability (n = 30); and endogenous zinc losses via urine, feces, or integument (n = 40) met the inclusion criteria. Four reviewers extracted data and two reviewers checked for accuracy.

DATA ANALYSES

Studies were synthesized narratively, and meta-analyses of zinc losses and gains as well the subgroups of age, type of feeding, country's income, and molar ratio of phytate to zinc were conducted. Meta-analysis revealed an overall mean (95%CI) urinary and endogenous fecal zinc excretion of 17.48 µg/kg/d (11.80-23.15; I2 = 94%) and 0.07 mg/kg/d (0.06-0.08; I2 = 82%), respectively, with a mean fractional zinc absorption of 26.75% (23.69-29.81; I2 = 99%). Subgrouping by age revealed differences in mean values associated with the transition from milk-based diets to solid food during the first 3 years of life.

CONCLUSION

This review synthesizes data that may be used to formulate zinc requirements in young children. Results should be interpreted with caution because of considerable heterogeneity in the evidence.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42020215236.

Zinc Kinetics Correlate With Length-for-Age z Scores in Bangladeshi Infants

OBJECTIVES

Stunting [length-for-age z score (LAZ) <-2] has multiple causes and is prevalent in areas with low dietary zinc (Zn) intake. Zinc kinetics from non-stunted infants were used in a published model for predicting linear growth; here, we directly measure zinc kinetics in stunted infants.

METHODS

Zinc kinetics were determined in 9-month-old Bangladeshi infants (n = 10), who were non-wasted [weight-for-length z score (WLZ) > -2], ranging in LAZ from -2.9 to -0.43. Stable isotopes were administered 2 hours after a meal as oral ( 70 Zn) and intravenous ( 67 Zn) tracers. After isotope administration, blood was sampled within 5 hours and all urine and feces were collected for 24 hours. Urine was sampled twice-daily out to 9 days. Data were analyzed by compartmental modeling. Daily zinc intake was estimated by the model as the sum of zinc used for growth plus that lost via urine and feces. Zinc absorbed (the amount required to maintain steady state) was the sum of zinc used for growth plus urine and endogenous fecal excretions.

RESULTS

The LAZ score correlated with serum zinc concentration ( R = 0.77, P = 0.001), urinary zinc excretion ( R = 0.66, P = 0.010), and fractional zinc absorption from calculated daily intake ( R = 0.58, P = 0.030). In stunted infants (n = 8), the amount of zinc absorbed did not increase with calculated zinc intake unlike published values for non-stunted infants.

CONCLUSIONS

Zinc kinetics in Bangladeshi infants correlate with LAZ and show that malabsorption of supplemental sources of zinc may occur in stunted infants.

Zinc Fortification: Current Trends and Strategies

Zinc, through its structural and cofactor roles, affects a broad range of critical physiological functions, including growth, metabolism, immune and neurological functions. Zinc deficiency is widespread among populations around the world, and it may, therefore, underlie much of the global burden of malnutrition. Current zinc fortification strategies include biofortification and fortification with zinc salts with a primary focus on staple foods, such as wheat or rice and their products. However, zinc fortification presents unique challenges. Due to the influences of phytate and protein on zinc absorption, successful zinc fortification strategies should consider the impact on zinc bioavailability in the whole diet. When zinc is absorbed with food, shifts in plasma zinc concentrations are minor. However, co-absorbing zinc with food may preferentially direct zinc to cellular compartments where zinc-dependent metabolic processes primarily occur. Although the current lack of sensitive biomarkers of zinc nutritional status reduces the capacity to assess the impact of fortifying foods with zinc, new approaches for assessing zinc utilization are increasing. In this article, we review the tools available for assessing bioavailable zinc, approaches for evaluating the zinc nutritional status of populations consuming zinc fortified foods, and recent trends in fortification strategies to increase zinc absorption.

Metallomics analysis for early assessment and individualized intervention of neurodevelopmental disorders

The children today are in the midst of the epidemic of neurodevelopmental disorders. In this metallomics study for the scalp hair samples of total 2550 children with autistic disorders (2108 males and 442 females aged 0-15 year), it was demonstrated that near one half of the infantile individuals aged 0-3 year are suffering from zinc deficiency and toxic metal burdens. Zinc level correlated closely to the index of zinc/iron ratio more than zinc/copper ratio. Furthermore, there were significant relationships between zinc deficiency and toxic metal burdens such as lead and aluminum which were inversely associated with not only zinc level but also zinc/iron ratio with higher regression coefficients of r = -0.486 and -0.551 (p < 0.00001), respectively. High-significant inverse association was detected between zinc and molybdenum concentration (r = -0.509) and also between zinc/iron ratio and molybdenum (r = -0.548). These findings suggest that infantile zinc deficiency relates to the high burdens of not only toxic but also some essential metals such as molybdenum, iron and manganese and that these various mineral imbalances play principal roles to the etiology of neurodevelopmental disorders. We expect that the early assessment and intervention of the mineral imbalances (or dis-homeostasis) in individual child open an avenue for evidence-based individualized treatment of neurodevelopmental disorders and also of the comorbid immune disorders, in near future.

Nutrient-Optimized Beef Enhances Blood Levels of Vitamin D and Selenium among Young Women

Bovine meat provides healthy nutrients but has also been negatively linked to greenhouse gases and non-communicable diseases. A double-blind intervention study was carried out to compare beef meat from bulls fed with feed supplemented with selenium, vitamin D, E, K (SeDEK-feed), and n-3, or REGULAR feed. Thirty-four young healthy women (19–29 years old) consumed 300 g of these beef types per day for 6 days in a cross-over design. Diet registrations, blood samples, anthropometric measurements, and clinical data were collected four times. Both beef diets were higher than their habitual diet in protein, fat, saturated fat, and several micronutrients; contained more vegetables and fewer carbohydrates and were followed by a higher feeling of satiety. The SeDEK beef had higher amounts of selenium, vitamin 25-hydroxyvitamin D3 (25(OH)D3), E, and K (MK4), and increased serum selenium and 25(OH)D3 from the participants’ normal values if they were below 85 µg/L of selenium and 30 nmol of 25(OH)D3/L, respectively. Our study showed that optimized beef increased serum selenium in young women having moderate selenium levels and improved blood 25(OH)D3 in a woman having low to normal 25(OH)D3. Meat should be optimized to increase specific consumer groups’ needs for selenium and vitamin D.

Reduced Fractional Absorption of Zinc in Children With Environmental Enteropathy in Zambia

OBJECTIVES

We measured fractional absorption of zinc (FAZ) in children with environmental enteropathy (EE) and carried out transcriptomic analysis of biopsies from these children in order to compare FAZ to histology of intestinal biopsies, expression of zinc transporter genes, and biomarkers of enteropathy.

METHODS

Fractional absorption of a standardized aqueous dose of zinc was measured by a dual isotope ratio technique in a cohort of children ages between 9 and 24 months in Lusaka, Zambia, who all had non-responsive stunting. Gene expression analysis was carried out on biopsies through RNA sequencing using an Illumina HiSeq2000 platform.

RESULTS

All 33 children had histological features of environmental enteropathy and plasma zinc concentrations below the lower limit of normal. Measured FAZ ranged from 0.18 to 0.93; all values >0.55 were observed in girls. FAZ was negatively correlated with faecal myeloperoxidase (MPO) (ρ = -0.51, n = 17; P = 0.04) and faecal calprotectin (ρ = -0.50, n = 16; P = 0.05), but not blood biomarkers. Of 41 genes with known roles in zinc metabolism, only three metallothionein genes were significantly correlated with FAZ.

CONCLUSIONS

Zinc homeostasis is impaired in children with environmental enteropathy, and was inversely correlated with mucosal inflammation. Reduced FAZ without specific changes in expression of most zinc transporter genes could be explained by reduced absorptive surface area due to villus/microvillus atrophy.

Exchangeable Zinc Pool Size Reflects Form of Zinc Supplementation in Young Children and Is Not Associated with Markers of Inflammation

A sensitive and reliable biomarker of zinc status has yet to be identified, but observational research suggests that the exchangeable zinc pool (EZP) size may be a possible biomarker. This randomized, placebo-controlled trial aimed to compare the change in EZP size from baseline to endline in 174 children who were preventatively supplemented with 10 mg of zinc as part of a multiple micronutrient power (MNP) or as a standalone dispersible tablet for 24 weeks versus a placebo powder. The effects of systemic inflammation on EZP size were also evaluated. Zinc stable isotopes were administered intravenously to children at baseline and endline, and the EZP was measured by the urine extrapolation method. A total of 156 children completed the study with the zinc dispersible tablet group having the greatest increase in EZP (14.1 mg) over 24 weeks when compared with the MNP group (6.8 mg) (p < 0.01) or placebo group (2.0 mg) (p < 0.001). Median EZP size was not different between children with normal or elevated serum inflammatory markers. EZP size was responsive to longitudinal zinc supplementation and reflected the expected difference in bioavailability for two forms of supplementation. The apparent absence of an effect of inflammation on EZP size may offer an advantage for use as a biomarker for group comparisons between different interventions.

Determinants of Children's Fruit Intake in Teso South Sub-County, Kenya-A Multi-Phase Mixed Methods Study among Households with Children 0-8 Years of Age

Fruits are micronutrient-rich sources which are often underrepresented in children’s diets. More insights into the determinants of children’s fruit consumption are needed to improve nutrition education in Teso South Sub-County, Kenya. A multiphase mixed method study was applied among 48 farm households with children 0–8 years of age. A market survey together with focus group discussions were used to design a formative research approach including qualitative and quantitative data collection methods. The unavailability of fruits and the inability to plant fruit trees in the homesteads were the main challenges to improve fruit consumption behaviour, although a number of different fruit species were available on the market or in households. Perceived shortage of fruits, financial constraints to purchase fruits and taste were important barriers. Fruits as snacks given between meals was perceived as helpful to satisfy children. The mean number of fruit trees in the homesteads was positively associated with fruit consumption. Field trials are needed to test how best fruit trees within home gardens and on farms can be included, acknowledging limited space and constraints of households with young children. This should be combined with nutrition education programs addressing perceptions about the social and nutrient value of fruits for children.

Calcium exacerbates the inhibitory effects of phytic acid on zinc bioavailability in rats

BACKGROUND

Complementary feeding of breastfed infants with foods high in bioavailable zinc (Zn) can help meet physiological requirements for Zn. Some infant cereals contain high concentrations of phytic acid (PA) and calcium (Ca) that may reduce absorbable Zn.

OBJECTIVES

This study measured PA, Zn and Ca concentrations in selected infant cereals sold in Canada and investigated the effects of dietary PA and Ca at concentrations present in infant cereals on Zn bioavailability in rats.

METHODS AND RESULTS

Male Sprague-Dawley rats (36-day old) were fed a control diet containing normal Zn (29.1 mg/kg) and Ca (4.95 g/kg) or six test diets (n = 12/diet group). Test diets were low in Zn (8.91-9.74 mg/kg) and contained low (2.16-2.17 g/kg), normal (5.00-5.11 g/kg) or high (14.6-14.9 g/kg) Ca without or with added PA (8 g/kg). After 2 weeks, rats were killed and Zn status of the rats was assessed. PA, Zn and Ca concentrations in infant cereals (n = 20) differed widely. PA concentrations ranged from undetectable to 16.0 g/kg. Zn and Ca concentrations ranged from 7.0-29.1 mg/kg and 0.8-13.4 g/kg, respectively. The [PA]/[Zn] and [PA × Ca]/[Zn] molar ratios in infants cereals with detectable PA (16 of 20 cereals) ranged from 22-75 and 0.9-14.9 mol/kg, respectively, predicting low Zn bioavailability. Body weight, body composition (lean and fat mass), right femur weight and length measurements and Zn concentrations in serum and femur indicated that diets higher in Ca had a more pronounced negative effect on Zn status of rats fed a PA-supplemented diet. Addition of PA to the diet had a greater negative effect on Zn status when Ca concentration in the diet was higher.

CONCLUSION

These results show that, in rats, higher concentrations of dietary Ca and PA interact to potentiate a decrease in bioavailable Zn and may suggest lower Zn bioavailability in infant cereals with higher PA and Ca concentrations.

Does zinc with and without iron co-supplementation have effect on motor and mental development of children? A systematic review and meta-analysis

BACKGROUND

Effects of zinc with and without iron co-supplementation on child development are uncertain therefore the aims of this systematic review were to explore whether supplementation with zinc alone and zinc with iron in children aged 0-5 years old have beneficial or adverse effects on their mental and motor development.

METHOD

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science and Scopus until July 2020 and included randomized controlled trials, which assessed effects of zinc supplementation with and without iron in children less than 5 years old on mental and motor development. Data were pooled by random effects model and the Standardized Mean Differences (SMDs) with 95% confidence interval were estimated. The heterogeneity was assessed by I2.

RESULTS

Twenty-five studies with 11,559 participants were eligible to be included in this systematic review. Meta-analysis was conducted with eight articles that used Bayley Scales of Infant and Toddler Development II. We concluded that zinc alone and zinc with iron co-supplementation do not have beneficial or adverse effect on child mental and motor development at 6 and 12 months of age with low to moderate quality of the evidence. Furthermore, Zinc supplementation does not have any long term effect on child development in preschool and school age children.

CONCLUSION

Most included studies did not show the efficacy of zinc with and without iron co-supplementation on child mental and motor development up to 9 years old age. Further Randomized Controlled Trials (RCTs) need to be taken into considerations the context-based differences between countries with special focus on socio-economic differences.

Nutritional Adequacy of Commercial Complementary Cereals in Germany

Commercial cereals are among the first complementary foods fed to infants in Germany and elsewhere. The purpose of this national survey is to describe the nutritional adequacy of commercial complementary cereals. A comprehensive, cross-sectional survey of cereal manufacturer websites (n = 15) was conducted from March to April 2019. Food labels were analyzed for iron, zinc, iodine, sodium, and sugar contents in commercial complementary cereals, and ingredient lists were evaluated for whole grains and added sugars. Preparation instructions were evaluated for the type of liquid recommended for reconstitution. Among 164 commercial complementary cereals, few contain iron (n = 43, 26%), zinc (n = 23, 14%) or iodine (n = 43, 26%). Sodium contents fall within EU thresholds. Most cereals were single grain, containing only wheat (n = 54), with half of the products (n = 86, 52%) containing whole grains. The average carbohydrate content of dry cereals is 69 g/100 g ± 9 g of which 14 ± 15 g is sugar. Preparation instructions for breakfast porridges and cereals recommend formula or toddler milk, while few recommend human milk (n = 13, 18%). Few commercial complementary cereals contain appreciable amounts (at least 15% of daily reference values) of zinc, iron, or iodine. A quarter of cereal carbohydrates are sugar and one-third of the products contain added sugars. Future directives should stipulate minimum micronutrient levels, strictly regulate sugar contents, and include human milk among preparation instructions.

Caregiver Perceptions and Acceptability of a Provitamin A Carotenoid, Iron and Zinc Rich Complementary Food Blend Prepared from Common Bean and Pumpkin in Rural Uganda

Ugandan children are vulnerable to vitamin A deficiency (VAD), iron deficiency (ID) and zinc deficiency (ZnD) because they are fed on complementary foods (CFs) low in vitamin A, iron and zinc. This study developed a novel provitamin A carotenoid (PVAC), iron and zinc rich common bean pumpkin blend (BPB) complementary food (CF) from locally available pumpkin and common bean in Uganda and aimed to determine its acceptance, compared to a control pumpkin blend (PB). Seventy caregivers participated in the study. The sensory attributes (taste, colour, aroma, texture and general acceptability) of BPB and PB were rated using a five-point facial hedonic scale (1 = very bad, 2 = bad, 3 = neutral, 4 = good, 5 = very good). Focus group discussions (FGDs) were conducted to assess the perceptions of caregivers about the BPB. The chi square test was used to detect the proportion difference for each sensory attribute between BPB and PB, whilst FGD data were analysed by thematic analysis. A proportion of 64% to 96% of the caregivers rated both BPB and PB as acceptable (good to very good) for all the sensory attributes. There was no significant difference in caregiver acceptability for all attributes between BPB and PB (p > 0.05). Caregivers had positive perceptions about the taste, texture, aroma and colour of the BPB. Caregivers were keen to know the specific varieties of common bean and pumpkin used to formulate the PVAC, iron and zinc rich BPB. In conclusion, BPB was acceptable to caregivers, and they were interested to know how to prepare and use it as a CF.

Trajectory of vitamin D, micronutrient status and childhood growth in exclusively breastfed children

This study aimed to compare the trajectory of serum 25(OH)D, micronutrient levels, and anthropometric measurements between exclusively breastfed and mixed-fed children. This is a prospective cohort study. Anthropometric measurements of the children were obtained during scheduled clinical visits. Tests for 25(OHD), ferritin, zinc and complete blood count were performed yearly until 3 years of age. Clinical records and questionnaires on dietary habits were obtained. The results showed that despite official recommendations on vitamin D/iron supplements for breastfed children, less than 10% of our exclusively breastfed children received regular supplements. Thus, after 1 year, the odds for having iron deficiency anemia and vitamin D insufficiency were 9 [95% CI, 4-19] and 6 [95% CI, 2-16], respectively. Longitudinal follow-up showed the prevalence of iron deficiency to decrease from 34% at 1 year to 2% at age 3 years. However, the prevalence of vitamin D insufficiency remained persistently high throughout the first three years of life (60% at 1 to 44% at 3 years). Very few children had zinc deficiency. Anthropometric measurements showed exclusively breastfed children to have lower mean z-scores for body weight and height when compared to mixed-fed children after 12 months. In conclusion, children who were exclusively breastfed for longer than 4 months without proper supplement were more likely to have transient iron deficiency anemia and persistent vitamin D insufficiency. Their growth became relatively slower after infancy. Whether this was associated with underlying inadequate serum vitamin D and iron level remains an important issue to be explored.

A meat- or dairy-based complementary diet leads to distinct growth patterns in formula-fed infants: a randomized controlled trial

Background

Protein intake from cow milk–based infant formula has been associated with rapid weight gain and increased adiposity, but the effect of protein from complementary foods has not been prospectively evaluated, and the effect of protein from sources other than formula during complementary feeding is not clear.

Objective

The aim of this study was to directly compare the effect of protein from 2 common complementary food sources, meat and dairy, on infant growth and weight trajectory.

Design

Healthy term, formula-fed infants were recruited from the metro Denver area, matched by sex and race/ethnicity and randomly assigned to a meat or a dairy complementary food group from 5 to 12 mo of age. Total protein intake during this 7-mo intervention was ∼3 g ⋅ kg⁻¹ ⋅ d⁻¹ for both groups. Intakes of infant formula, cereal, fruit, and vegetables were ad libitum. Caregivers also completed 3-d diet records at 5, 10, and 12 mo of age. Anthropometric measures were obtained during monthly home visits, and blood samples were collected at 5 and 12 mo of age.

Results

Sixty-four infants completed the intervention (meat: n = 32; dairy: n = 32). The average total protein intake (mean ± SD) increased from 2.01 ± 0.06 g ⋅ kg⁻¹ ⋅ d⁻¹ at 5 mo to 3.35 ±0.12 g ⋅ kg⁻¹ ⋅ d⁻¹ at 12 mo and did not differ between groups. Over time, weight and weight-for-age z score increased by 0.48 ± 0.07. However, there was a significant group-by-time interaction for both length-for-age z score (LAZ) and weight-for-length z score (WLZ). Post hoc analysis showed that LAZ increased in the meat group (+0.33 ± 0.09; P = 0.001 over time) and decreased in the dairy group (−0.30 ± 0.10; P = 0.0002 over time); WLZ significantly increased in the dairy group (0.76 ± 0.21; P = 0.000002 over time) compared with the meat group (0.30 ± 0.17; P = 0.55 over time). Insulin-like growth factor I and insulin-like growth factor-binding protein 3 both increased over time without group differences.

Conclusions

Protein source may have an important role in regulating growth. In these formula-fed older infants, meat- and dairy-based complementary foods led to distinct growth patterns, especially for length. This trial was registered at www.clinicaltrials.gov as NCT02142647.

Zinc Absorption and Endogenous Fecal Zinc Losses in Bangladeshi Toddlers at Risk for Environmental Enteric Dysfunction

OBJECTIVES

Environmental enteric dysfunction (EED) impairs zinc absorption from food, and zinc deficiency may contribute to the poor growth associated with EED. We examined zinc absorption from a standardized aqueous zinc dose, and habitual daily endogenous fecal zinc excretion (EFZ) and compared these outcomes between children grouped by the lactulose to mannitol ratio (L:M).

METHODS

Bangladeshi toddlers (18-24 months) with low (<0.09) and high (≥0.09) L:M were administered isotope-labeled 3 mg aqueous zinc in the fasted state. Fractional absorption of zinc (FAZ) and EFZ were measured by dual stable isotope tracer method and an isotope dilution method, respectively. Secondary aims included examining relationships of biomarkers of systemic and intestinal inflammation and gut function with FAZ and EFZ.

RESULTS

Forty children completed the study; nearly all had evidence of EED. No differences in zinc homeostasis measurements (mean ± SD) were observed between high and low L:M groups: FAZ was 0.38 ± 0.19 and 0.31 ± 0.19, respectively; both figures were within estimated reference range. Means of EFZ were 0.73 ± 0.27 and 0.76 ± 0.20 mg/day for high and low L:M, respectively, and were 10% to 15% above estimated reference range. Regression analyses indicated that biomarkers of systemic inflammation were directly associated with increasing FAZ, consistent with increased gut permeability. Biomarkers of intestinal inflammation were negatively associated with EFZ, consistent with low-zinc intake and chronic deficiency.

CONCLUSIONS

In these children at risk of EED, endogenous zinc losses were not markedly increased. Results suggest that efforts to improve zinc status in EED should focus on substantially improving zinc intakes.

Complementary feeding and micronutrient status: a systematic review

BACKGROUND

Proper nutrition during early life is critical for growth and development.

OBJECTIVES

The aim was to describe systematic reviews conducted by the Nutrition Evidence Systematic Review team for the USDA and the Department of Health and Human Services Pregnancy and Birth to 24 Months Project to answer the following: What is the relation between 1) timing of introduction of complementary foods and beverages (CFBs) or 2) types and/or amounts of CFBs consumed and micronutrient status (iron, zinc, vitamin D, vitamin B-12, folate, and fatty acid status)?

METHODS

A literature search identified articles from developed countries published from January 1980 to July 2016 that met the inclusion criteria. Data were extracted and risk of bias assessed. Evidence was qualitatively synthesized to develop a conclusion statement, and the strength of the evidence was graded.

RESULTS

Nine articles addressed the timing of CFB introduction and 31 addressed types or amounts or both of CFBs. Moderate evidence suggests that introducing CFBs at age 4 mo instead of 6 mo offers no advantages or disadvantages in iron status among healthy full-term infants. Evidence is insufficient on the timing of CFB introduction and other micronutrient status outcomes. Strong evidence suggests that CFBs containing iron (e.g., meat, fortified cereal) help maintain adequate iron status or prevent deficiency in the first year among infants at risk of insufficient iron stores or low intake. Benefits for infants with sufficient iron stores (e.g., infant formula consumers) are less clear. Moderate evidence suggests that CFBs containing zinc (e.g., meat, fortified cereal) support zinc status in the first year and CFB fatty acid composition influences fatty acid status. Evidence is insufficient with regard to types and amounts of CFBs and vitamin D, vitamin B-12, and folate status, or the relation between lower-iron-containing CFBs and micronutrient status.

CONCLUSIONS

Several conclusions on CFBs and micronutrient status were drawn from these systematic reviews, but more research that addresses specific gaps and limitations is needed.

Effectiveness of provision of animal-source foods for supporting optimal growth and development in children 6 to 59 months of age

BACKGROUND

Adequate nutrients early in life promote cognitive development and are critical for proper growth and functioning. The effect of individual nutrients consumed through food is often not the same as consuming the same nutrients in supplementary form due to 'food synergy', the biological and chemical interrelations that occur between nutrients. Animal-source foods, such as eggs, meat, fish, and dairy, are energy dense and contain multiple micronutrients and essential fatty acids with high bioavailability. The benefits of animal-source foods may include higher food synergy relative to fortified foods as well as decreasing dependence on external suppliers of fortified foods.

OBJECTIVES

To assess the effectiveness of animal-source foods compared to any other feeding interventions or no intervention in improving growth and developmental outcomes in children aged 6 to 59 months.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, 18 other databases, and three trials registers up to August 2018. We also contacted authors and known experts in the field for assistance in identifying ongoing or unpublished data, and searched the reference lists of included studies and reviews, and websites of relevant organizations, for other studies that may not have been captured by our electronic searches.

SELECTION CRITERIA

We included randomized controlled trials and quasi-randomized controlled trials of any duration, where children between 5 months and 59 months (6 years) of age were provided with an animal-source food (e.g. consumption of milk, meat, or eggs), prepared with any cooking method, compared with any intervention or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility using prespecified criteria, extracted data, assessed risk of bias, and graded the quality of the evidence using the GRADE approach.

MAIN RESULTS

Study characteristicsWe included 6 studies that analyzed data from 3036 children aged 5 to 50 months. The studies were conducted in China, the Democratic Republic of Congo, Ecuador, Guatemala, Pakistan, the USA, and Zambia, and lasted between 5 and 12 months. Three studies were funded, in part, by government entities; one study was supported by a nonprofit organization. Two studies did not report a funding source.Three studies compared the effects of feeding an animal-source food with a fortified (iron or iron and zinc), or unfortified cereal; two used a control group with no intervention; one compared a meat-based diet to a dairy-based diet. The types of animal-source foods tested included yogurt, eggs, cheese, lyophilized (freeze-dried) beef product, ground and frozen pork, puréed and jarred beef with gravy or pork, and powdered whey protein.We judged four studies to be at unclear risk of bias overall; three studies because they were funded by an industry with a plausible interest in the outcome of the intervention; and one study because there was insufficient information to assess five of the seven bias 'Risk of bias' domains. We judged two of the six studies to be at high risk of bias overall; one study because there was significant baseline imbalance in length-for-age z scores (LAZ) between groups and evidence of selective reporting; the other study because there there was both a significant baseline imbalance in LAZ and weight-for-age z scores (WAZ) between groups, and a large-scale social media campaign that may have influenced care received at home in the control group.Key resultsAnimal-source foods versus cereal-based foods or no interventionFive studies (2972 children) measured change in linear growth with either height-for-age z scores (HAZ) or LAZ. Three studies (592 children) reported a significant increase in HAZ and LAZ in the intervention group compared to the control group. Two studies (2380 children) reported a decline in LAZ in both groups. In one study (1062 children) there was no difference between the groups in the rate of decline; in the other (1318 children) the decrease in LAZ was significantly smaller in the intervention group.Five studies (2972 children) measured weight gain using WAZ. Three studies (592 children) reported a significant increase in WAZ in the intervention group compared to the control group. In two studies (2380 children), WAZ decreased in both groups. In one of these studies (1318 children), the decrease in the intervention group was significantly smaller than in the control group. In the other study (1062 children), there was no difference between the groups.Three studies (1612 children) reported impacts on all-cause morbidity, but metrics were inconsistent between studies. One study with yogurt (402 children) reported a significant reduction in duration and incidence of diarrhea and upper respiratory infections in the intervention group. One study with eggs (148 children) reported a significant increase in the incidence of diarrhea in the intervention group, but this may have been due to cultural associations with eggs and gastrointestional problems. There were no other significant differences in fever, respiratory infections, or skin conditions between groups. The third study (1062 children) found no differences between intervention and control groups across morbidity measures.No studies reported data on anemia.Meat-based diet versus dairy-based dietOne study (64 children) measured change in LAZ and WAZ in infants fed either a meat-based diet or dairy-based diet. There was a significant increase in LAZ among infants consuming the meat-based diet and a significant decrease in LAZ among infants consuming a dairy-based diet. WAZ increased in both groups, with no significant difference between groups.The study did not assess all-cause morbidity or anemia.Quality of the evidenceWe rated the quality of the evidence as very low overall due to baseline imbalances between intervention and control groups, high heterogeneity in meta-analysis, and imprecision due to wide confidence intervals and inconsistent direction of effects. We have little confidence in the results; further research is likely to change the estimate of magnitude and direction of treatment effect.

AUTHORS' CONCLUSIONS

Given the limited quality of the evidence, we are uncertain of the effects of the provision of animal-source food versus cereal products or no intervention on the growth or development of children. More adequately powered trials with deliberately selected animal-source foods are needed.

Zinc Absorption from Micronutrient Powders Is Low in Bangladeshi Toddlers at Risk of Environmental Enteric Dysfunction and May Increase Dietary Zinc Requirements

Background

Environmental enteric dysfunction (EED), a chronic inflammatory disorder of the small bowel, is suspected to impair absorption of micronutrients, including zinc.

Objective

The objective of this study was to compare zinc absorption from micronutrient powder (MNP) over a range of zinc doses in young children screened for EED with use of the lactulose:mannitol ratio (L:M).

Methods

Bangladeshi children aged 18-24 mo, grouped according to high and low L:M (≥0.09 and <0.09, respectively), were randomly assigned to MNP with 0, 5, 10, or 15 mg Zn/sachet (10 subjects per dose per L:M group). Over a day, fractional absorption of zinc was measured from an MNP-fortified meal and from unfortified meals with stable isotope tracers; total daily absorbed zinc (TAZ, milligrams per day) was determined as the primary outcome. Secondary outcomes included investigation of relations of TAZ to intake, to physiologic requirement, and to other variables, including biomarkers of systemic and intestinal inflammation, using nonlinear models. TAZ was also compared with published data on child zinc absorption.

Results

In 74 subjects who completed the study, zinc absorption did not differ by L:M grouping. Most biomarkers of intestinal inflammation were elevated in both L:M groups. For combined L:M groups, mean ± SD TAZ for each MNP dose (0, 5, 10, and 15 mg/sachet) was 0.57 ± 0.30, 0.68 ± 0.31, 0.90 ± 0.43, and 1.0 ± 0.39 mg/d, respectively (P = 0.002), and exceeded the estimated physiologic requirement only for the 10- and 15-mg MNP doses. Zinc absorption was notably lower at all intake levels compared with published data (P < 0.0001) and was inversely related to serum α-1 acid glycoprotein and to fecal Entamoeba histolytica (P = 0.02).

Conclusion

Results indicate impaired absorption of zinc, which may predispose to zinc deficiency in young children with evidence of enteropathy. These findings suggest that current doses of zinc in MNP may be insufficient to yield zinc-related preventative benefits in similar settings. This study is registered at clinicaltrials.gov as NCT02758444.

Severely inadequate micronutrient intake among children 9-24 months in Nepal-The MAL-ED birth cohort study

Prevalence of micronutrient deficiencies is high among infants and children in low- and middle income countries, but knowledge about nutrient adequacy across the complementary feeding period is limited. We investigated probability of adequacy (PA) of breast milk and complementary food combined and nutrient density adequacy (NDA) of complementary food and tracking of NDA over time among 229 children from 9-24 months of age in Bhaktapur, Nepal. Monthly, 24 h dietary recalls (16 in total) were performed and subgrouped into four 4-month time periods. Ten micronutrients (thiamin, riboflavin, niacin, vitamin B6 , folate, vitamin C, vitamin A, calcium, iron, and zinc) were assessed. Nutrient density was defined as the amount of a nutrient in a child's complementary food per 100 kcal, whereas NDA was the nutrient density as percentage of the context specific desired nutrient density. Tracking of NDA was investigated using generalized estimating equations models. PA for B vitamins (except riboflavin), vitamin A, calcium, iron, and zinc (low absorption group) was very low (0% to 8%) at all time slots. Median (IQR) mean PA (of all 10 micronutrients) increased from 11% (9, 15) in the second to 21% (10, 35) in the last time slot. Median value for mean nutrient density adequacy of all micronutrients varied between 42% and 52%. Finally, tracking of NDA was low (correlation <0.30) or moderate (0.30-0.60) indicating poor association between the first and subsequent measurements of NDA. These findings raise grave concerns about micronutrient adequacy among young children in Nepal. Urgent interventions are needed.

Exchangeable Zinc Pool Size at Birth in Pakistani Small for Gestational Age and Appropriate for Gestational Age Infants Do Not Differ But Are Lower Than in US Infants

OBJECTIVES

Small for gestational age (SGA) infants are more susceptible to infectious morbidity and growth faltering compared to their appropriate for gestational age (AGA) counterparts. Zinc supplementation of SGA infants may be beneficial but the underlying susceptibility to zinc deficiency of SGA infants has not been examined.

METHODS

In a community-based, observational, longitudinal study in a peri-urban settlement of Karachi, Pakistan, we compared the size of the exchangeable zinc pools (EZPs) in term SGA and AGA infants at birth and at 6 months of age, hypothesizing that the EZP would be lower in the SGA group. To measure EZP size, a zinc stable isotope was intravenously administered within 48 hours of birth (n = 17 and 22) at 6 months (n = 11 and 14) in SGA and AGA infants, respectively. Isotopic enrichment in urine was used to determine EZP.

RESULTS

No significant difference was detected in the mean (±standard deviation) EZP between SGA and AGA infants at birth, with values of 9.8 ± 3.5 and 10.1 ± 4.1 mg/kg, respectively (P = 0.86), or at 6 months. Longitudinal EZP measurements demonstrated a significant decline in EZP relative to body weight in both groups at 6 months (P < 0.001). Mean EZP (adjusted for body weight) size at birth for the combined Pakistani groups was significantly lower than AGA infants at birth in the United States (P = 0.017).

CONCLUSIONS

These results did not support a difference in zinc endowment between SGA and AGA Pakistani infants. They, however, do suggest lower in utero zinc transfer to the fetus in a setting where poor maternal nutritional status may confer a high susceptibility to postnatal zinc deficiency.

Study Protocol for a Randomized, Double-Blind, Community-Based Efficacy Trial of Various Doses of Zinc in Micronutrient Powders or Tablets in Young Bangladeshi Children

Zinc is essential to supporting growth in young children especially for tissues undergoing rapid cellular differentiation and turnover, such as those in the immune system and gastrointestinal tract. Therapeutic zinc supplementation has been initiated in low-income countries as part of diarrhea treatment programs to support these needs for young children, but the effects of preventive supplemental zinc as a tablet or as a multiple micronutrient powder (MNP) on child growth and diarrheal disease are mixed and pose programmatic uncertainties. Thus, a randomized, double-blind community-based efficacy trial of five different doses, forms, and frequencies of preventive zinc supplementation vs. a placebo was designed for a study in children aged 9–11 months in an urban community in Dhaka, Bangladesh. The primary outcomes of this 24-week study are incidence of diarrheal disease and linear growth. Study workers will conduct in-home morbidity checks twice weekly; anthropometry will be measured at baseline, 12 weeks and 24 weeks. Serum zinc and other related biomarkers will be measured in a subsample along with an estimate of the exchangeable zinc pool size using stable isotope techniques in a subgroup. Therapeutic zinc will be provided as part of diarrhea treatment, in accordance with Bangladesh’s national policy. Therefore, the proposed study will determine the additional benefit of a preventive zinc supplementation intervention. The protocol has been approved by the Institutional Review Boards (IRBs) of icddr,b and Children’s Hospital Oakland Research Institute (CHORI). The IRB review process is underway at the University of Colorado Denver as well.

Importance of Dietary Sources of Iron in Infants and Toddlers: Lessons from the FITS Study

Iron deficiency (ID) affects 13.5% of 1-2 years old children in the US and may have a negative impact on neurodevelopment and behavior. Iron-fortified infant cereal is the primary non-heme iron source among infants aged 6-11.9 months. The objective of this study was to compare iron intakes of infant cereal users with non-users. Data from the Feeding Infants and Toddlers Study 2008 were used for this analysis. Based on a 24-h recall, children between the ages of 4-17.9 months were classified as 'cereal users' if they consumed any amount or type of infant cereal and 'non-users' if they did not. Infant cereal was the top source of dietary iron among infants aged 6-11.9 months. The majority of infants (74.6%) aged 6-8.9 months consumed infant cereal, but this declined to 51.5% between 9-11.9 months and 14.8% among 12-17.9 months old toddlers. Infant cereal users consumed significantly more iron than non-users across all age groups. Infants and toddlers who consume infant cereal have higher iron intakes compared to non-users. Given the high prevalence of ID, the appropriate use of infant cereals in a balanced diet should be encouraged to reduce the incidence of ID and ID anemia.

Upregulation of Zinc Absorption Matches Increases in Physiologic Requirements for Zinc in Women Consuming High- or Moderate-Phytate Diets during Late Pregnancy and Early Lactation

Background: Estimated physiologic requirements (PRs) for zinc increase in late pregnancy and early lactation, but the effect on dietary zinc requirements is uncertain.Objective: The aim of this study was to determine changes in daily fractional absorbed zinc and total absorbed zinc (TAZ) from ad libitum diets of differing phytate contents in relation to physiologic zinc requirements during pregnancy and lactation.Methods: This was a prospective observational study of zinc absorption at 8 (phase 1) and 34 (phase 2) wk of gestation and 2 (phase 3) and 6 (phase 4) mo of lactation. Participants were indigenous Guatemalan women of childbearing age whose major food staple was maize and who had been randomly assigned in a larger study to either of 2 ad libitum feeding groups: low-phytate maize (LP; 1.6 mg/g; n = 14) or control maize (C; 7.1 mg/g; n = 8). Total dietary zinc (milligrams per day, TDZ) and phytate (milligrams per day) were determined from duplicate diets and fractional absorption (FAZ) by dual isotope ratio technique (TAZ = TDZ × FAZ). All variables were examined longitudinally and by group and compared with PRs. TAZ values at later phases were compared with phase 1. Measured TAZ was compared with predicted TAZ for nonpregnant, nonlactating (NPNL) women.Results: TAZ was greater in the LP group than in the C group at all phases. All variables increased from phase 1 to phases 2 and 3 and declined at phase 4. TAZ increased by 1.25 mg/d (P = 0.045) in the C group and by 0.81 mg/d (P = 0.058) in the LP group at phase 2. At phase 3, the increases were 2.66 mg/d (P = 0.002) in the C group and 2.28 mg/d (P = 0.0004) in the LP group, compared with a 1.37-mg/d increase in PR. Measured TAZ was greater than predicted values in phases 2-4.Conclusions: Upregulation of zinc absorption in late pregnancy and early lactation matches increases in PRs of pregnant and lactating women, regardless of dietary phytate, which has implications for dietary zinc requirements of pregnant and lactating women.

A moderate increase in dietary zinc reduces DNA strand breaks in leukocytes and alters plasma proteins without changing plasma zinc concentrations

BACKGROUND

Food fortification has been recommended to improve a population's micronutrient status. Biofortification techniques modestly elevate the zinc content of cereals, but few studies have reported a positive impact on functional indicators of zinc status.

OBJECTIVE

We determined the impact of a modest increase in dietary zinc that was similar to that provided by biofortification programs on whole-body and cellular indicators of zinc status.

DESIGN

Eighteen men participated in a 6-wk controlled consumption study of a low-zinc, rice-based diet. The diet contained 6 mg Zn/d for 2 wk and was followed by 10 mg Zn/d for 4 wk. To reduce zinc absorption, phytate was added to the diet during the initial period. Indicators of zinc homeostasis, including total absorbed zinc (TAZ), the exchangeable zinc pool (EZP), plasma and cellular zinc concentrations, zinc transporter gene expression, and other metabolic indicators (i.e., DNA damage, inflammation, and oxidative stress), were measured before and after each dietary-zinc period.

RESULTS

TAZ increased with increased dietary zinc, but plasma zinc concentrations and EZP size were unchanged. Erythrocyte and leukocyte zinc concentrations and zinc transporter expressions were not altered. However, leukocyte DNA strand breaks decreased with increased dietary zinc, and the level of proteins involved in DNA repair and antioxidant and immune functions were restored after the dietary-zinc increase.

CONCLUSIONS

A moderate 4-mg/d increase in dietary zinc, similar to that which would be expected from zinc-biofortified crops, improves zinc absorption but does not alter plasma zinc. The repair of DNA strand breaks improves, as do serum protein concentrations that are associated with the DNA repair process. This trial was registered at clinicaltrials.gov as NCT02861352.

Predictors of the Size of the Exchangeable Zinc Pool Differ between Children and Adults

BACKGROUND

The size of the rapidly exchanging pool of body zinc has been suggested as having potential utility as a biomarker of zinc status. Knowledge of the relations of exchangeable zinc pool (EZP) size to relevant variables is necessary to adequately evaluate its use as a biomarker.

OBJECTIVE

We used regression analysis to investigate associations of EZP with age, sex, body size, and zinc nutrition variables.

METHODS

Data were compiled from 18 isotope tracer studies of zinc absorption in 247 children and adults (248 observations) in which EZP and relevant variables (e.g., weight, age, absorbed zinc) were measured. Linear regression analyses were performed separately on data from adults and children.

RESULTS

In children, EZP was most strongly associated with weight (r = 0.78). The best-fitting regression models of EZP (R² ≥ 0.68) had weight or age and weight-for-age z score as predictors. Other variables had little effect on EZP when controlling for weight. Absorbed zinc was observed to be a predictor of EZP only in zinc intervention trials of infants. The mean EZP/wt was 4 mg/kg between 8 and 120 mo of age. In adults, EZP was observed to vary in a complex manner with (in order of importance) age, absorbed zinc, weight, sex, and plasma zinc concentration. EZP data from zinc-deprived subjects were lower than the 95% prediction interval of a model of normative data.

CONCLUSIONS

EZP was observed to maintain a constant size relative to weight and was influenced only slightly by other factors in children. In contrast, EZP in adults varied with several factors, including absorbed zinc, and was statistically smaller in zinc-deprived individuals. The findings suggest that EZP may have utility as an indicator of zinc status in adults, but there is less evidence for this in children. Additional data are needed to reach a definitive conclusion.

Development of complementary feeding recommendations for 12–23-month-old children from low and middle socio-economic status in West Java, Indonesia: contribution of fortified foods towards meeting the nutrient requirement

Inadequate nutrient intake as part of a complementary feeding diet is attributable to poor feeding practices and poor access to nutritious foods. Household socio-economic situation (SES) has an influence on food expenditure and access to locally available, nutrient-dense foods and fortified foods. This study aimed to develop and compare complementary feeding recommendations (CFR) for 12–23-month-old children in different SES and evaluate the contribution of fortified foods in meeting nutrient requirements. A cross-sectional survey was conducted in low and medium SES households (n 114/group) in urban Bandung district, West Java province, Indonesia. Food pattern, portion size and affordability were assessed, and CFR were developed for the low SES (LSES) and middle SES (MSES) using a linear programming (LP) approach; two models – with and without fortified foods – were run using LP, and the contribution of fortified foods in the final CFR was identified. Milk products, fortified biscuits and manufactured infant cereals were the most locally available and consumed fortified foods in the market. With the inclusion of fortified foods, problem nutrients were thiamin in LSES and folate and thiamin in MSES groups. Without fortified foods, more problem nutrients were identified in LSES, that is, Ca, Fe, Zn, niacin and thiamin. As MSES consumed more fortified foods, removing fortified foods was not possible, because most of the micronutrient-dense foods were removed from their food basket. There were comparable nutrient adequacy and problem nutrients between LSES and MSES when fortified foods were included. Exclusion of fortified foods in LSES was associated with more problem nutrients in the complementary feeding diet.

An Opinion on "Staging" of Infant Formula: A Developmental Perspective on Infant Feeding

Breast milk is a dynamic fluid with compositional changes occurring throughout the period of lactation. Some of these changes in nutrient concentrations reflect the successively slowing growth rate and developmental changes in metabolic requirements that infants undergo during the first year of life. Infant formula, in contrast, has a static composition, intended to meet the nutritional requirements of infants from birth to 6 or 12 months of age. To better fit the metabolic needs of infants and to avoid nutrient limitations or excesses, we suggest that infant formulas should change in composition with the age of the infant, that is, different formulas are created/used for different ages during the first year of life. We propose that specific formulas for 0 to 3 months (stage 1), 3 to 6 months (stage 2), and 6 to 12 months (stage 3) of age may be nutritionally and physiologically advantageous to infants. Although this initially may impose some difficult practical/conceptual issues, we believe that this staging concept would improve nutrition of formula-fed infants and, ultimately, improve outcomes and make their performance more similar to that of breast-fed infants.

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 Absorption Is Not Related to Dietary Phytate Intake in Infants and Young Children Based on Modeling Combined Data from Multiple Studies

BACKGROUND

It is widely understood that the 2 primary factors affecting dietary zinc absorption in adults are the quantities of zinc and phytate in the diet. Although a similar association of absorption to dietary zinc and phytate is presumed to exist in children, to our knowledge, no large-scale examination of the relation of zinc absorption to dietary and growth factors has been conducted.

OBJECTIVE

The goal was to apply an adult absorption model and related models to data from zinc absorption studies of infants and children in order to determine the nature of the relation of zinc absorption to dietary zinc and phytate, age, body size, and zinc homeostatic variables.

METHODS

Data from 236 children between 8 and 50 mo of age were obtained from stable-isotope studies of zinc absorption. Statistical and mechanistic models were fit to the data using linear and nonlinear regression analysis.

RESULTS

The effect of dietary phytate on zinc absorption when controlling for dietary zinc was very small and not statistically discernable (P = 0.29). A 500-mg/d increase in dietary phytate reduced absorbed zinc by <0.04 mg/d. Absorption was observed to vary with age, weight, and height (P < 0.0001) when controlling for dietary zinc. For example, absorption from 6 mg/d of dietary zinc increased by as much as 0.2 mg/d with a 12-mo increase in age. Absorption varied with weight and exchangeable zinc pool size (0.01 < P < 0.05) when controlling for dietary zinc and age.

CONCLUSIONS

The absence of a detectable phytate effect on zinc absorption raises caution about use of dietary phytate:zinc molar ratios to predict zinc bioavailability and does not support phytate reduction as a strategy to improve zinc status of young children. The effect of age on zinc absorption and the absence of a phytate effect should facilitate estimations of dietary zinc needs in young children.

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.

Zinc absorption from biofortified maize meets the requirements of young rural Zambian children

BACKGROUND

The zinc content of maize, a major global food staple, is generally insufficient alone to meet the requirements of young children.

OBJECTIVES

The primary objective of this study was to determine whether substitution of biofortified maize (34 μg zinc/g grain) for control maize (21 μg zinc/g) was adequate to meet zinc physiologic requirements in young children for whom maize was the major food staple. A secondary objective was to compare total daily zinc absorption when maize flour was fortified with zinc oxide to a total concentration of 60 μg zinc/g.

METHODS

Participants included 60 rural Zambian children with a mean age of 29 mo who were randomly assigned to receive 1 of 3 maize types (control, biofortified, or fortified) all of which were readily consumed (>100 g on 1 d). Total daily zinc intake (from maize and low-zinc relish) was determined from duplicate diet collections. Multiplication by fractional absorption of zinc, measured by a dual isotope ratio technique, determined the total daily zinc absorption on the day the test meals were given.

RESULTS

The mean ± SD total daily zinc intake (milligrams per day) from the biofortified maize (5.0 ± 2.2) was higher (P < 0.0001) than for the control maize (2.3 ± 0.9). Intake of zinc from the fortified maize (6.3 ± 2.6) did not differ from the biofortified maize. Fractional absorption of zinc from control maize (0.28 ± 0.10) did not differ from the biofortified maize (0.22 ± 0.06). Total daily absorption of zinc (milligrams per day) from the biofortified maize (1.1 ± 0.5) was higher (P = 0.0001) than for the control maize (0.6 ± 0.2), but did not differ from the fortified maize (1.2 ± 0.4).

CONCLUSIONS

These results indicate that feeding biofortified maize can meet zinc requirements and provide an effective dietary alternative to regular maize for this vulnerable population. This trial was registered at clinicaltrials.gov as NCT02208635.

Meat as complementary food for older breastfed infants and toddlers: a randomized, controlled trial in rural China

BACKGROUND

Because of its contribution to dietary diversity and to favorable intakes of micronutrients, including iron and zinc, meat is hypothesized to be a valuable complementary food for the infant and young child. However, the evidence base remains limited.

OBJECTIVE

To compare the difference in anthropometric measurements of rural Chinese infants and toddlers 6 to 18 months of age who received a daily supplement of meat or cereal for 12 months.

METHODS

This cluster-randomized, controlled study provided a daily supplement of either meat (n = 514, 20 clusters) or cereal (n = 957, 40 clusters) starting as a first complementary food at 6 months of age. Anthropometric measurements were assessed longitudinally.

RESULTS

After 12 months of intervention, the meat group (δ13.01 ± 1.9 cm) had greater (p = .01) linear growth than the cereal group (δ12.75 ± 1.8 cm) and a smaller decrease in length-for-age z-score (LAZ) over time (-0.43 ± 0.72 in the meat group vs. -0.54 ± 0.67 in the cereal group), after adjustment for baseline length, LAZ, maternal education, work status, and maternal height and weight.

CONCLUSIONS

Linear growth was modestly greater in the meat group than in the cereal group. LAZ was substantially negative at 6 months, and the intervention did not prevent ongoing decline over the course of the study.

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.

Zinc absorption from micronutrient powder is low but is not affected by iron in Kenyan infants

Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP - Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups' mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.

Zinc deficiency in infants and children: a review of its complex and synergistic interactions

Zinc deficiency is estimated to contribute to over half a million deaths per year in infants and children under 5 years of age. This paper reviews the features of mild-to-moderate zinc deficiency, which include growth faltering, deficits in immune function and altered integrity and function of the gastro-intestinal tract. Sub-clinical features include oxidative stress and a pro-inflammatory state. The homeostatic response to low dietary zinc intake by increasing absorption is limited, especially if the source of zinc is of poor bioavailability, and conservation of endogenous intestinal losses is a critical component of adaptation. Owing to low zinc intakes, older breastfed infants, especially those of low birthweight, are predictably at risk of zinc deficiency if complementary food choices are unfortified and/or low in zinc. Host factors such as young age, poor intra-uterine zinc accretion owing to poor maternal status and/or prematurity, and gastro-intestinal dysfunction also potently predispose to zinc deficiency. Environmental enteropathy, which is prevalent in low-resource settings, may substantially impair zinc absorption and/or increase endogenous losses, and thus lead to relatively high zinc requirements. Emerging evidence highlights common features between chronic inflammation and zinc deficiency, and each may exacerbate the other. More investigations of zinc homeostasis in populations in low-resource settings are needed to better quantify absorption capacity and losses. Effective preventive strategies must address potentially higher zinc requirements as well as the underlying context that perpetuates a vicious cycle of zinc deficiency and multiple adverse outcomes.

High protein intake from meat as complementary food increases growth but not adiposity in breastfed infants: a randomized trial

BACKGROUND

High intake of cow-milk protein in formula-fed infants is associated with higher weight gain and increased adiposity, which have led to recommendations to limit protein intake in later infancy. The impact of protein from meats for breastfed infants during complementary feeding may be different.

OBJECTIVE

We examined the effect of protein from meat as complementary foods on growth and metabolic profiles of breastfed infants.

DESIGN

This was a secondary analysis from a trial in which exclusively breastfed infants (5-6 mo old from the Denver, CO, metro area) were randomly assigned to receive commercially available pureed meats (Meat group; n = 14) or infant cereal (Cereal group; n = 28) as their primary complementary feedings for ∼ 5 mo. Anthropometric measures and diet records were collected monthly from 5 to 9 mo of age; intakes from complementary feeding and breast milk were assessed at 9 mo of age.

RESULTS

The Meat group had significantly higher protein intake, whereas energy, carbohydrate, and fat intakes from complementary feeding did not differ by group over time. At 9 mo of age, mean (± SEM) intakes of total (complementary feeding plus breast milk) protein were 2.9 ± 0.6 and 1.4 ± 0.4 g · kg(-1) · d(-1), ∼ 17% and ∼ 9% of daily energy intake, for Meat and Cereal groups, respectively (P < 0.001). From 5 to 9 mo of age, the weight-for-age z score (WAZ) and length-for-age z score (LAZ) increased in the Meat group (ΔWAZ: 0.24 ± 0.19; ΔLAZ: 0.14 ± 0.12) and decreased in the Cereal group (ΔWAZ: -0.07 ± 0.17; ΔLAZ: -0.27 ± 0.24) (P-group by time < 0.05). The change in weight-for-length z score did not differ between groups. Total protein intake at 9 mo of age and baseline WAZ were important predictors of changes in the WAZ (R(2) = 0.23, P = 0.01).

CONCLUSION

In breastfed infants, higher protein intake from meats was associated with greater linear growth and weight gain but without excessive gain in adiposity, suggesting that potential risks of high protein intake may differ between breastfed and formula-fed infants and by the source of protein.

Food Based Complementary Feeding Strategies for Breastfed Infants: What's the Evidence that it Matters?

The period of complementary feeding represents a major portion of the 1000 day critical window and thus impacts a period of substantial and dynamic infant development. This review highlights and synthesizes findings of several recent studies conducted to evaluate food based strategies on outcomes related to micronutrient status, growth and neurocognitive development. Particular emphasis is placed on interventions using meat or fortified products to impact iron and zinc intakes, due to the dependence of breastfed infants on complementary food choices to meet requirements for these two critical micronutrients. Regular consumption of modest amounts of meat or fortified cereals provides adequate absorbed zinc to meet estimated physiologic requirements, whereas homeostatic adaptation to lower zinc intake from unfortified cereal/plant staples is inadequate to meet requirements. Iron fortification of cereals may be somewhat more effective than meat to improve iron status, but neither prevents iron deficiency in breastfed infants, even in westernized settings. Improvements in the quality of complementary foods have had very modest effects on linear growth in settings where stunting is prevalent. Maternal education is strongly associated with both linear growth and with child neurodevelopment. The determinants of early growth faltering are more complex and intractable than 'simple' dietary deficiencies of micronutrients. Solutions to growth faltering in young children most likely need to be multi-factorial, and almost certainly will need to start earlier than the complementary feeding period.

Patterns of nutrients' intake at six months in the northeast of Italy: a cohort study

BACKGROUND

Adequate complementary feeding is recognized as an important predictor of health later in life. The objective of this study was to describe the feeding practices and nutrients' intake, and their association with breastfeeding at six months of age, in a cohort of infants enrolled at birth in the maternity hospital of Trieste, Italy.

METHODS

Out of 400 infants enrolled at birth, 268 (67%) had complete data gathered through a 24-hour feeding diary on three separate days at six months, and two questionnaires administered at birth and at six months. Data from feeding diaries were used to estimate nutrients' intakes using the Italian food composition database included in the software. To estimate the quantity of breastmilk, information was gathered on the frequency and length of breastfeeds.

RESULTS

At six months, 70% of infants were breastfed and 94% were given complementary foods. The average daily caloric intake was higher in non-breastfed (723 Kcal) than in breastfed infants (547 Kcal, p < 0.001) due to energy provided by complementary foods (321 vs. 190 Kcal, p < 0.001) and milk (363 vs. 301 Kcal, p = 0.007). Non-breastfed infants had also higher intakes of carbohydrates, proteins, and fats. The mean intake of macronutrients was within recommended ranges in both groups, except for the higher protein intake in non-breastfed infants. These consumed significantly higher quantities of commercial baby foods than breastfed infants.

CONCLUSIONS

Contrary to what is recommended, 94% of infants were not exclusively breastfed and were given complementary foods at six months. The proportion of daily energy intake from complementary foods was around 50% higher than recommended and with significant differences between breastfed and non-breastfed infants, with possible consequences for future nutrition and health.

Executive summary: Evaluating the evidence base to support the inclusion of infants and children from birth to 24 mo of age in the Dietary Guidelines for Americans--"the B-24 Project"

The Dietary Guidelines for Americans (DGA) are the cornerstone of US government efforts to promote health and prevent disease through diet and nutrition. The DGA currently provides guidelines for ages ≥ 2 y. In an effort to determine the strength of the evidence to support the inclusion of infants and children from birth to age 24 mo, the partner agencies led by the Department of Health and Human Services Office of Disease Prevention and Health Promotion and the USDA Center for Nutrition Program and Policy initiated the project entitled "Evaluating the evidence base to support the inclusion of infants and children from birth to 24 months of age in the Dietary Guidelines for Americans--the B-24 Project." This project represents the first step in the process of applying systematic reviews to the process of deciding whether the evidence is sufficient to include this age group in future editions of the DGA. This supplement includes the B-24 Executive Summary, which describes the B-24 Project and the deliberations of the 4 working groups during the process of developing priority topics for the systematic review, and a research agenda to address the critical gaps. Also included in this supplement issue is an article on the Nutrition Evidence Library methodology for developing systematic review questions and articles from the invited content presenters at the B-24 Prime meeting.

Absorbed zinc and exchangeable zinc pool size are greater in Pakistani infants receiving traditional complementary foods with zinc-fortified micronutrient powder

Adequacy of zinc intake from breast milk alone becomes marginal in relation to infant requirements by around 6 mo of age. Simple and cost-effective strategies are needed at the population level to ensure adequate intakes of zinc in infants and toddlers in populations at risk of zinc deficiency. We determined the amount of absorbed zinc (AZ) from a micronutrient powder (MNP) without and with 10 mg of zinc (MNP+Zn) added to local complementary foods used in Pakistan and the impact on the exchangeable zinc pool (EZP) size. As a nested study within a large, prospective, cluster randomized trial, 6-mo-old infants were randomly assigned to receive MNP or MNP+Zn. Stable isotope methodology was applied after ∼3 and 9 mo of use to measure AZ from MNP-fortified test meals of rice-lentils (khitchri) and EZP. Nineteen infants per group completed the first metabolic studies and 14 and 17 infants in the MNP and MNP+Zn groups, respectively, completed the follow-up studies. AZs were (mean ± SD) 0.1 ± 0.1 and 1.2 ± 0.5 mg at the first point for the MNP and MNP+Zn groups, respectively (P < 0.001); results were nearly identical at the follow-up measurement. EZP did not differ between groups at the first measurement but was less in the MNP group (3.7 ± 0.6 mg/kg) than in the MNP+Zn group (4.5 ± 1.0 mg/kg) at the second measurement (P = 0.01). These data confirm that the MNP+Zn in khitchri were well absorbed and after 1 y of home fortification, zinc status assessed by EZP was significantly better for the MNP+Zn group. Additional field studies may be necessary to ascertain the adequacy of this dose for infants at high risk of deficiency. This trial was registered at ClinicalTrials.gov as NCT00705445.

Complementary Feeding: Critical Considerations to Optimize Growth, Nutrition, and Feeding Behavior

This review focuses on complementary feeding (CF) in westernized settings where primary health concerns are risk of obesity and micronutrient inadequacy. The current evidence is reviewed for: (1) when CF should be introduced, (2) what foods (nutrients and food types) should be prioritized and avoided, and (3) how the infant should be fed. Special attention is paid to the underlying physiological differences between breast- and formula-fed infants that often result in distinctly different nutritional and health risks. This difference is particularly acute in the case of micronutrient inadequacy, specifically iron and zinc, but is also relevant to optimal energy and macronutrient intakes. Emphasis is placed on the complex interplay among infants' early dietary exposures; relatively high energy and nutrient requirements; rapid physical, social and emotional development; and the feeding environment-all of which interact to impact health outcomes. This complexity needs to be considered at both individual and population levels and in both clinical and research settings.

Effects of different complementary feeding regimens on iron status and enteric microbiota in breastfed infants

OBJECTIVE

To compare iron status in breastfed infants randomized to groups receiving complementary feeding regimens that provided iron from fortified infant cereals or meats, and to examine the development of the enteric microbiota in these groups.

STUDY DESIGN

Forty-five exclusively breastfed 5-month-old infants were randomized to 1 of 3 feeding groups (FGs)-commercially available pureed meats, iron- and zinc-fortified infant cereals, or iron-only fortified infant cereals-as the first and primary complementary food through 9-10 months of age. Dietary iron was determined by monthly 3-day diet records. Iron status was assessed at the end of the study by measurements of hemoglobin, serum ferritin, and soluble transferrin receptor levels. In a subsample of 14 infants, enteric microbiota were profiled in monthly stool samples (5-9 months) by 16S ribosomal RNA gene pyrosequencing.

RESULTS

Infants in the 2 cereal FGs had 2- to 3-fold greater daily iron intakes versus the meat FG (P < .0001). More than one-quarter (27%) of the infants had a low serum ferritin level, and 36% were mildly anemic, with no significant differences by FG; more infants in the meat FG had a high soluble transferrin receptor value (P = .03). Sequence analysis identified differences by time and FG in the abundances of several bacterial groups, including significantly more abundant butyrate-producing Clostridium group XIVa in the meat FG (P = .01) CONCLUSION: A high percentage of healthy infants who were breastfed-only were iron-deficient, and complementary feeding, including iron exposure, influenced the development of the enteric microbiota. If these findings are confirmed, then reconsideration of strategies to both meet infants' iron requirements and optimize the developing microbiome may be warranted.