Efficacy of highly bioavailable zinc from fortified water: a randomized controlled trial in rural Beninese children

The Effect of Zinc Biofortified Wheat Produced via Foliar Application on Zinc Status: A Randomized, Controlled Trial in Indian Children

BACKGROUND

Agronomic zinc biofortification of wheat by foliar application increases wheat zinc content and total zinc absorption in humans.

OBJECTIVES

To assess the effect of agronomically biofortified whole wheat flour (BFW) on plasma zinc (PZC) compared with a postharvest fortified wheat (PHFW) and unfortified control wheat (CW) when integrated in a midday school meal scheme.

METHODS

We conducted a 20-wk double-blind intervention trial in children (4-12 y, n = 273) individually randomly assigned to 3 groups to receive a daily school lunch consisting of 3 chapattis prepared with the 3 different wheat flour types. Measurements of anthropometry, blood biochemistry, and leukocyte DNA strand breaks were conducted. We applied sparse serial sampling to monitor PZC over time, and analysis was performed using linear mixed-effects models.

RESULTS

Mean zinc content in BFW, PHFW, and CW were 48.0, 45.1, and 21.2 ppm, respectively (P < 0.001). Mean (standard deviation) daily zinc intakes in the study intervention in BFW, PHFW, and CW groups were 4.4 (1.6), 5.9 (1.9) and 2.6 (0.6) mg Zn/d, respectively, with intake in groups PHFW and BFW differing from CW (P < 0.001) but no difference between BFW and PHFW. There were no time effect, group difference, or group × time interaction in PZC. Prevalence of zinc deficiency decreased in the BFW (from 14.1%-11.2%), PHFW (from 8.9%-2.3%), and CW (9.8%-8.8%) groups, but there was no time × treatment interaction in the prevalence of zinc deficiency (P = 0.191). Compliance with consuming the study school meals was associated with PZC (P = 0.006). DNA strand breaks were not significantly associated with PZC (n = 51; r = 0.004, P = 0.945).

CONCLUSIONS

Consumption of either PHFW or BFW provided an additional ∼1.8 to 3.3 mg Zn/d, but it did not affect PZC or zinc deficiency, growth, or DNA strand breaks. This trial was registered on clinicaltrials.gov as NCT02241330 and ctri.nic.in as CTRI/2015/06/005913.

Including calcium-fortified water or flour in modeled diets based on local foods could improve calcium intake for women, adolescent girls, and young children in Bangladesh, Uganda, and Guatemala

Adequate calcium intake is essential for health, especially for infants, children, adolescents, and women, yet is difficult to achieve with local foods in many low- and middle-income countries. Previous analysis found it was not always possible to identify food-based recommendations (FBRs) that reached the calcium population recommended intake (PRI) for these groups in Bangladesh, Guatemala, and Uganda. We have modeled the potential contribution of calcium-fortified drinking water or wheat flour to FBR sets, to fill the remaining intake gaps. Optimized diets containing fortified products, with calcium-rich local foods, achieved the calcium PRI for all target groups. Combining fortified water or flour with FBRs met dietary intake targets for adolescent girls in all geographies and allowed a reduction from 3-4 to the more feasible 1-2 FBRs. Water with a calcium concentration of 100 mg/L with FBRs was sufficient to meet calcium targets in Uganda, but higher concentrations (400-500 mg/L) were mostly required in Guatemala and Bangladesh. Combining calcium-fortified wheat flour at 400 mg/100 g of flour and the FBR for small fish resulted in diets meeting the calcium PRI in Bangladesh. Calcium-fortified water or flour could improve calcium intake for vulnerable populations, especially when combined with FBRs based on locally available foods.

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.

Influence of Dairy Products on Bioavailability of Zinc from Other Food Products: A Review of Complementarity at a Meal Level

In this paper, we reviewed the role of dairy products in dietary zinc absorption. Dairy products can have a reasonable contribution for dietary zinc intake in Western diets, where dairy consumption is high. However, the co-ingestion of dairy products can also improve zinc absorption from other food products. Such improvements have been observed when dairy products (e.g., milk or yoghurt) were ingested together with food such as rice, tortillas or bread products, all of which are considered to be high-phytate foods with low inherent zinc absorption. For foods low in phytate, the co-ingestion of dairy products did not improve zinc absorption. Improved zinc absorption of zinc from high-phytate foods following co-ingestion with dairy products may be related to the beneficial effects of the citrate and phosphopeptides present in dairy products. Considering that the main dietary zinc sources in areas in the world where zinc deficiency is most prevalent are typically high in phytate, the inclusion of dairy products in meals may be a viable dietary strategy to improve zinc absorption.

Guts, Germs, and Iron: A Systematic Review on Iron Supplementation, Iron Fortification, and Diarrhea in Children Aged 4-59 Months

BACKGROUND

The impact of iron supplements and iron fortification on diarrhea in children is controversial, with some studies reporting an increase and others reporting no effect.

OBJECTIVE

The aim of the study was systematically assess the published literature on oral iron supplementation and fortification to evaluate its impact on diarrhea incidence among children aged 4-59 mo.

METHODS

Randomized controlled trials of oral iron supplementation or iron fortification that reported diarrheal outcomes in children aged 4-59 mo were identified from a systematic search of 5 databases.

RESULTS

Of the 906 records identified, 19 studies were found to fit the inclusion criteria for this systematic review. However, variable case definitions for diarrhea made meta-analysis impossible. Of the 19 studies, 7 (37%) studies showed a significant increase, either in overall diarrhea incidence or within a specific subgroup of the population, between iron-supplemented and control groups. Subgroups included children who were iron-replete and children undergoing their first month of iron intervention. Two studies reported an increase in bloody diarrhea. The remaining 12 (63%) studies showed no difference between iron-supplemented and control groups.

CONCLUSIONS

Studies on iron supplementation and fortification use divergent case definitions for diarrhea. A number of studies (37%) showed an increase in overall diarrhea incidence or within a specific subgroup of the population, between iron-supplemented and control groups, but the majority (63%) did not. In addition, there was no clear relation between diarrhea and type of intervention or amount of iron administered observed. In future studies, we recommend that diarrhea be clearly defined and consistently recorded as a secondary outcome. Antibiotic status of participants receiving iron should also be collected to help assess possible drug interactions resulting in a "red stool effect." Finally, further microbiome research is required to better understand the effects of oral iron on specific bacterial species in the colon.

Effectiveness of zinc-fortified water on zinc intake, status and morbidity in Kenyan pre-school children: a randomised controlled trial

OBJECTIVE

Zn deficiency and diarrhoea are prevalent and may coexist in children living in low-resource settings. Recently, a novel approach for delivering Zn via microbiologically treated, Zn-fortified water was shown to be effective in improving Zn status in West African schoolchildren. We assessed the effectiveness of Zn-fortified, microbiologically purified water delivered as a household intervention on Zn intake, status and morbidity in children aged 2-6 years from rural western Kenya.

DESIGN

Randomised controlled trial. Intervention included households assigned to water treatment device with (ZFW) or without (FW) Zn delivery capability SETTING: Rural households in Kisumu, western Kenya.

SUBJECTS

Children aged 2-6 years.

RESULTS

The ZFW group had higher dietary Zn intake compared with the FW group. ZFW contributed 36 and 31 % of daily requirements for absorbable Zn in children aged 2-3 and 4-6 years, respectively, in the ZFW group. Consumption of Zn-fortified water resulted in lower prevalence of reported illness (risk ratio; 95 % CI) in the ZFW group compared with the FW group: for cold with runny nose (0·91; 0·83, 0·99; P=0·034) and abdominal pain (0·70; 0·56, 0·89; P=0·003) in the intention-to-treat analysis and for diarrhoea (0·72; 0·53, 0·96; P=0·025) in the per-protocol analysis. We did not detect an effect of treatment on plasma Zn concentration.

CONCLUSIONS

Daily consumption of Zn-fortified, microbiologically treated water results in increased intake of absorbable dietary Zn and may help in preventing childhood infections in pre-school children in rural Africa.

Combining food-based dietary recommendations using Optifood with zinc-fortified water potentially improves nutrient adequacy among 4- to 6-year-old children in Kisumu West district, Kenya

Children in developing countries often face multiple micronutrient deficiencies. Introduction of zinc-fortified water can increase zinc intake, but additional recommendations are required to address overall diet nutrient adequacy. We developed and tested food-based recommendations (FBRs) that included zinc-fortified water for children aged between 4 and 6 years from rural Kenya to achieve the best possible nutrient adequacy. Dietary intakes of 60 children aged 4-6 years, from Kisumu West district, Kenya, were assessed using a quantitative multipass 24-hr recall. Linear programming model parameters were derived, including a list of foods consumed, median serving sizes, and distribution of frequency of consumption. By using the Optifood linear programming tool, we developed FBRs for diets including zinc-fortified water. FBRs with nutrient levels achieving ≥70% recommended nutrient intake (RNI) of the World Health Organization/Food and Agriculture Organization of the United Nations RNI for most of the 12 considered nutrients were selected as the final recommendations for the children. With no FBRs and no zinc-fortified water, percent RNI coverage range was between 40% and 76% for zinc, improving to 66-101% after introduction of zinc-fortified water. The final set of FBRs achieved nutrient adequacy for all nutrients except for vitamin A (25% RNI) and folate (68% RNI). Introduction of zinc-fortified water combined with FBRs will likely improve the nutrient adequacy of diets consumed by children in Kenya but needs to be complemented with alternative interventions to ensure dietary adequacy.

Sensitivity of fatty acid desaturation and elongation to plasma zinc concentration: a randomised controlled trial in Beninese children

Zn status may affect fatty acid (FA) metabolism because it acts as a cofactor in FA desaturase and elongase enzymes. Zn supplementation affects the FA desaturases of Zn-deficient rats, but whether this occurs in humans is unclear. We evaluated the associations between baseline plasma Zn (PZn) concentration and plasma total phospholipid FA composition, as well as the effect of daily consumption of Zn-fortified water on FA status in Beninese children. A 20-week, double-blind randomised controlled trial was conducted in 186 school age children. The children were randomly assigned to receive a daily portion of Zn-fortified, filtered water delivering on average 2·8 mg Zn/d or non-fortified filtered water. Plasma total phospholipid FA composition was determined using capillary GLC and PZn concentrations by atomic absorption spectrometry. At baseline, PZn correlated positively with dihomo-γ-linolenic acid (DGLA, r 0·182; P=0·024) and the DGLA:linoleic acid (LA) ratio (r 0·293; P<0·000), and negatively with LA (r -0·211; P=0·009) and the arachidonic acid:DGLA ratio (r -0·170; P=0·036). With the intervention, Zn fortification increased nervonic acid (B: 0·109; 95 % CI 0·001, 0·218) in all children (n 186) and more so in children who were Zn-deficient (n 60) at baseline (B: 0·230; 95 % CI 0·023, 0·488). In conclusion, in this study, Zn-fortified filtered water prevented the reduction of nervonic acid composition in the plasma total phospholipids of children, and this effect was stronger in Zn-deficient children. Thus, Zn status may play an important role in FA desaturation and/or elongation.

Zinc Absorption from Milk Is Affected by Dilution but Not by Thermal Processing, and Milk Enhances Absorption of Zinc from High-Phytate Rice in Young Dutch Women

Background: Milk has been suggested to increase zinc absorption. The effect of processing and the ability of milk to enhance zinc absorption from other foods has not been measured directly in humans.Objective: We aimed to assess zinc absorption from 1) milk undergoing various processing and preparatory steps and 2) from intrinsically labeled high-phytate rice consumed with milk or water.Methods: Two randomized crossover studies were conducted in healthy young women [age:18-25 y; body mass index (in kg/m²): 20-25]: 1) a milk study (n = 19) comparing the consumption of 800 mL full-fat ultra-high temperature (UHT) milk [heat-treated milk (HTM)], full-fat UHT milk diluted 1:1 with water [heat-treated milk and water (MW)], water, or unprocessed (raw) milk (UM), each extrinsically labeled with ⁶⁷Zn, and 2) a rice study (n = 18) comparing the consumption of 90 g intrinsically ⁶⁷Zn-labeled rice with 600 mL of water [rice and water (RW)] or full-fat UHT milk [rice and milk (RM)]. The fractional absorption of zinc (FAZ) was measured with the double-isotope tracer ratio method. In vitro, we assessed zinc extraction from rice blended into water, UM, or HTM with or without phytate.Results: FAZ from HTM was 25.5% (95% CI: 21.6%, 29.4%) and was not different from UM (27.8%; 95% CI: 24.2%, 31.4%). FAZ from water was higher (72.3%; 95% CI: 68.7%, 75.9%), whereas FAZ from MW was lower (19.7%; 95% CI: 17.5%, 21.9%) than HTM and UM (both P < 0.01). FAZ from RM (20.7%; 95% CI: 18.8%, 22.7%) was significantly higher than from RW (12.8%; 95% CI: 10.8%, 14.6%; P < 0.01). In vitro, HTM and UM showed several orders of magnitude higher extraction of zinc from rice with HTM than from rice with water at various phytate concentrations.Conclusions: Milk enhanced human FAZ from high-phytate rice by 62% compared with water. Diluting milk with water decreases its absorption-enhancing proprieties, whereas UHT processing does not. This trial was registered at the Dutch trial registry as NTR4267 (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4267).

Rural Beninese Children Are at Risk of Zinc Deficiency According to Stunting Prevalence and Plasma Zinc Concentration but Not Dietary Zinc Intakes

BACKGROUND

Three commonly recommended indicators for risk assessment of population zinc deficiency are stunting rates among children aged <5 y, prevalence of inadequate dietary zinc intake, and prevalence of low plasma zinc (PZn). Data on zinc status in Benin are mainly drawn from stunting rates and data on PZn and dietary zinc intake are lacking.

OBJECTIVES

The aims of this study were 1) to assess the risk of zinc deficiency in preschool and school-age children from rural communities in northern Benin by means of the 3 indicators for population assessment, 2) to evaluate their level of agreement, and 3) to identify predictors of PZn and height-for-age z scores (HAZ).

METHODS

We analyzed preintervention data collected during 2 efficacy trials and cross-sectionally assessed the risk of zinc deficiency in preschool (1-5 y, n = 326) and school-age children (5-10 y, n = 272) by 1) conducting a 3-d weighed food record survey, coupled with direct zinc and phytic acid analysis of consumed foodstuffs, and calculating usual dietary zinc intakes in a subsample of school-age children (n = 36); 2) analyzing PZn in all children (n = 598); and 3) measuring anthropometry indexes for assessment of stunting (HAZ <-2 SD) in all children (n = 594) and in <5-y-old children only (n = 273). We derived predictors of PZn and HAZ by using multivariate regression with mixed-effect models.

RESULTS

Prevalence of inadequate intakes of zinc ranged from 11% to 80% depending on whether the estimated average requirements (EARs) by the International Zinc Nutrition Consultative Group or the EARs derived from the WHO's recommended nutrient intakes were used. Prevalence of low PZn adjusted for acute-phase protein status was 45.7%, with higher rates among preschoolers than school-age children (P = 0.002). The stunting rate in <5-y-old children was 51.3%. PZn was predicted by age, methodologic factors, and socioeconomic status, whereas HAZ was predicted by age, sex, hemoglobin, and socioeconomic status.

CONCLUSIONS

The prevalence of <5-y stunting and the prevalence of low PZn indicate that the risk of zinc deficiency is elevated in this population. Risk estimates based on the prevalence of inadequacy of zinc intakes varied depending on the EARs used, and a consensus would facilitate nutrition survey evaluations. These trials were registered at clinicaltrials.gov as NCT01472211 and NCT01790321.