Fractional Zinc Absorption Research Articles

Modeling Zinc Absorption in the Adult Population of Colombia: Insights for Nutritional Evaluation and Intervention Strategies.

Zinc is a vital trace element, yet its deficiency is common in various populations. This study addresses the gap in understanding zinc intake and its relationship with key nutritional parameters in a Colombian population. We analyzed data from 12,987 individuals, focusing on the daily intake of zinc, phytate, protein, and calcium, and used the phytate/zinc molar ratio as an input parameter in the Miller et al. (2013) model. This model was employed to estimate the total absorbed zinc (TAZ) and the fractional absorption of zinc (FAZ). Our findings highlight a general trend towards insufficient intake compared to the standards of the Institute of Medicine (IOM) and Colombia, with a significant percentage of the population falling below the estimated average requirement (EAR) and recommended daily allowance (RDA) for zinc, underscoring the need for targeted nutritional strategies. Our study contributes to a broader understanding of zinc nutrition and public health implications in Colombia, providing a basis for future dietary guidelines and health interventions.

Biofortified Yellow-Fleshed Potatoes Provide More Absorbable Zinc than a Commonly Consumed Variety: A Randomized Trial Using Stable Isotopes in Women in the Peruvian Highlands

BackgroundZinc-biofortified potatoes have considerable potential to reduce zinc deficiency because of their low levels of phytate, an inhibitor of zinc absorption, and their high consumption, especially in the Andean region of Peru. ObjectivesThe purpose of this study was to measure fractional and total zinc absorption from a test meal of biofortified compared with regular potatoes. MethodsWe undertook a single-blinded randomized crossover study (using 67Zn and 70Zn stable isotopes) in which 37 women consumed 500-g biofortified or regular potatoes twice a day. Urine samples were collected to determine fractional and total zinc absorption. ResultsThe zinc content of the biofortified potato and regular potato was 0.48 (standard deviation [SD]: 0.02) and 0.32 (SD: 0.03) mg/100 g fresh weight, respectively. Mean fractional zinc absorption (FZA) from the biofortified potatoes was lower than from the regular potatoes, 20.8% (SD: 5.4%) and 25.5% (SD: 7.0%), respectively (P < 0.01). However, total zinc absorbed was significantly higher (0.49; SD: 0.13 and 0.40; SD: 0.11 mg/500 g, P < 0.01, respectively). ConclusionsThe results of this study demonstrate that biofortified potatoes provide more absorbable zinc than regular potatoes. Zinc-biofortified potatoes could contribute toward reducing zinc deficiency in populations where potatoes are a staple food.This trial was registered at clinicaltrials.gov as NCT05154500.

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.

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. 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. 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. 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. 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. 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. PROSPERO registration number CRD42020215236.

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

Stunting [length-for-age z score (LAZ) &lt;-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. Zinc kinetics were determined in 9-month-old Bangladeshi infants (n = 10), who were non-wasted [weight-for-length z score (WLZ) &gt; -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. 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. Zinc kinetics in Bangladeshi infants correlate with LAZ and show that malabsorption of supplemental sources of zinc may occur in stunted infants.

Slc39a4 in the small intestine predicts zinc absorption and utilization: a comprehensive analysis of zinc transporter expression in response to diets of varied zinc content in young mice

Zinc homeostasis is primarily maintained by zinc transporters that regulate zinc uptake and efflux in the small intestine; however, the relative contribution of the many zinc transporters identified (Slc39a1-14, Slc30a1-10) to dietary zinc absorption and utilization remains unknown. The objective of this study was to determine the expression of Slc39a1-14 and Slc30a1-10 in the small intestine and their relative contribution to dietary zinc absorption in mice. Five-week-old male C57BL/6J mice were fed modified AIN-93G diets containing <1, 30, or 100ppm zinc (n=15 mice/diet). Following 1 week of feeding, mice were given an oral gavage containing 67Zn and liver and plasma isotope appearance was determined 6-h later by ICP-MS. Expression of Slc39a1-14 and Slc30a1-10 was determined in mucosa from duodenum, jejunum, and ileum. Plasma and liver total zinc concentrations were not different after one week of feeding (P>.05). Liver and plasma appearance of 67Zn was greater in mice fed <1ppm compared to the 30ppm (P<.0001) and 100ppm (P<.0001) zinc diets. With the exception of Slc39a2, Slc39a12, Slc30a3, and Slc30a8, the remaining zinc transporters were expressed across all diets and intestinal segments. Expression of Slc39a4, Slc39a11, and Slc30a6 changed with diet (Pdiet<.05 for all); expression of Slc39a5, Slc39a7, Slc39a11, Slc39a14, Slc30a1, Slc30a2, Slc30a4, Slc30a5, Slc30a7, and Slc30a10 changed by intestinal segment (Psegment<.05 for all). Slc39a4 was the only transporter positively associated with liver (r2=0.316, P<.001) and plasma (r2=0.189, P<.01) 67Zn appearance. Although most zinc transporters are expressed in the small intestine, intestinal Slc39a4 predicts fractional zinc absorption and utilization in young mice.

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

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. 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. 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. 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.

The Effects of Short-Term Zinc Feeding on Zinc Absorption and Zinc Transporter Expression in the Small Intestine of Mice

Abstract Objectives Zinc homeostasis is primarily maintained by zinc transporters that regulate zinc uptake and efflux in the small intestine; however, no study to date has comprehensively examined zinc transporter expression in the small intestine of mice fed varying levels of dietary zinc. The objective of this study was to determine the effects of zinc absorption and zinc transporter expression in the small intestine of mice fed varying levels of zinc for one week. Methods Seven-week-old male C57BL/6 J mice were randomized to either a standard AIN-93 G diet containing 30 ppm zinc (zinc adequate) or modified AIN-93 G diets containing &amp;lt;1 ppm (zinc deficient) or 100 ppm zinc (zinc supplemented) for one week (n = 5–10/diet). Mice were given an oral gavage containing a slurry of zinc deficient feed and 10 μg 67 Zn; plasma isotope appearance was determined 6-h later by ICP-MS. Gene expression of Slc39a1–14 and Slc30a1–10 was determined in each intestinal segment (duodenum, jejunum, and ileum) by RT-qPCR. Results Plasma and liver zinc concentrations were not different after one week of feeding (P &amp;gt; 0.05 for both). Plasma appearance of 67 Zn was greater in mice fed the zinc deficient (mean ± SD: 0.36 ± 0.03 ng/mL) compared to the zinc adequate (0.22 ± 0.03 ng/mL) and zinc supplemented (0.22 ± 0.03 ng/mL, P &amp;lt; 0.0001 for both) diets. With the exception of Slc39a12, Slc30a3, and Slc30a8, the remaining zinc transporters were expressed across all diets and intestinal segments. Expression of Slc39a1, Slc39a4, Slc39a5, Slc39a7, Slc39a9, Slc39a11, Slc39a14, Slc30a2, Slc30a4, Slc30a5, Slc30a6, and Slc30a9 changed with diet (Pdiet &amp;lt; 0.05 for all); expression of Slc39a3, Slc39a7, Slc39a9 and Slc30a5 changed by intestinal segment (Psegment &amp;lt; 0.05 for all). Of those transporters expressed, Slc39a4 was positively associated with plasma appearance of 67 Zn (r = 0.645, P &amp;lt; 0.0001) and increased 7-fold in mice consuming the zinc deficient diet compared to the zinc adequate and zinc supplemented diets (P &amp;lt; 0.0001 for both). Conclusions Although most zinc transporters are expressed in the small intestine and likely function in concert, fluctuations in fractional zinc absorption are positively correlated with Slc39a4 expression in the small intestine. Funding Sources The views expressed herein are those of the authors and do not reflect official policy of the Army, DoD, or US Government. Supported by MRDC.

Effect of exogenous phytase added to small-quantity lipid-based nutrient supplements (SQ-LNS) on the fractional and total absorption of zinc from a millet-based porridge consumed with SQ-LNS in young Gambian children: a randomized controlled trial

Dietary phytate inhibits zinc absorption from composite meals in adults. The objective of this study was to investigate the effect of adding exogenous phytase to a small-quantity lipid-based nutrient supplement (SQ-LNS) on zinc absorption among young children. In a double-blind randomized controlled trial, intraindividual differences in fractional and total absorption of zinc (FAZ and TAZ, respectively) from a millet-based porridge containing SQ-LNS with and without phytase were measured in 30 asymptomatic children 18-23 mo of age in the Kiang West district of The Gambia. Using a crossover design, children received for 1 d each porridge test meals with 20 g SQ-LNS containing 8 mg zinc and either 1) exogenous phytase or 2) no exogenous phytase. The test meals were provided on consecutive days in randomized order. FAZ was measured using a triple stable isotope tracer ratio technique with Zn-67 and Zn-70 as oral tracers and Zn-68 as the intravenous tracer. Twenty-six participants completed the study. The prevalence of stunting and wasting were 20% and 13%, respectively; no children had low plasma zinc concentrations (<65 μg/dL). Total mean ± SD dietary zinc intake from the test meals was 7.3±2.2 mg (phytate:zinc molar ratio=3.1±0.3, not accounting for phytase activity). Mean FAZ increased from 8.6%±1.3% to 16.0%±1.3% when exogenous phytase was added to the SQ-LNS product (P<0.001). Mean TAZ from test meals containing SQ-LNS with phytase was more than double that from test meals containing SQ-LNS without phytase (1.1±0.1 mg and 0.5±0.1 mg, respectively; P<0.001). The addition of exogenous phytase to SQ-LNS increased both FAZ and TAZ. These results suggest that phytate reduction may be an important strategy to increase zinc absorption among young children. This trial was registered at clinicaltrials.gov as NCT02668133.

Exogenous Phytase Added to Lipid Based Nutrient Supplements Increases Fractional and Total Absorption of Zinc Among Young Gambian Children: A Randomized Controlled Trial (OR07-01-19)

ObjectivesDietary phytate inhibits zinc absorption from composite meals in adults. The objective of this study was to investigate the efficacy of adding exogenous phytase to a small-quantity lipid based nutrient supplement (SQ-LNS) on zinc absorption among young children. MethodsIn a double-blind randomized controlled trial, intra-individual differences in fractional and total absorption of zinc (FAZ and TAZ, respectively) from SQ-LNS with and without phytase were measured in 30 asymptomatic 18–23 month old children in the Kiang West district of The Gambia. Using a cross-over design, children received for one day each test meals of a millet-based porridge with 20 g SQ-LNS containing 8 mg zinc and either: 1) exogenous phytase (∼500 phytase units (FTU)) or 2) no exogenous phytase. The test meals were provided on consecutive days in randomized order. FAZ was measured using a dual-stable isotope tracer ratio technique with 67 Zn and 70 Zn as oral tracers, randomized independently of SQ-LNS product, and 68 Zn as the intravenous tracer. TAZ was calculated as the product of total dietary zinc (TDZ) intake from test meals (i.e., porridge, SQ-LNS and stable isotope) and FAZ. FAZ and TAZ were compared for meals with and without phytase using mixed-models ANOVA with product, study day, and oral isotope allocation as fixed effects and individual child as a random effect. ResultsTwenty-six participants completed the study. The prevalence of stunting, underweight and wasting were 20%, 30% and 13%, respectively; no children had low plasma zinc concentrations (< 65 μg/dL). TDZ and phytate intakes from the test meals were 7.2 ± 2.2 mg and 182.9 ± 64.7 mg, respectively (phytate: zinc molar ratio = 2.4 ± 0.2). Mean FAZ increased from 8.6 ± 1.3% to 16.0 ± 1.3% when exogenous phytase was added to the SQ-LNS product (P = 0.0002). Mean TAZ from porridge test meals containing SQ-LNS with phytase was more than double that from test meals containing SQ-LNS without phytase (1.12 ± 0.07 mg and 0.52 ± 0.07 mg, respectively; P < 0.0001). ConclusionsThe addition of exogenous phytase to a meal of millet-based porridge with SQ-LNS improved both FAZ and TAZ. These results suggest that phytate reduction may be an important strategy to improve zinc absorption among young children. Funding SourcesNutriset, SAS.

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

ABSTRACTBackgroundEnvironmental enteric dysfunction (EED), a chronic inflammatory disorder of the small bowel, is suspected to impair absorption of micronutrients, including zinc.ObjectiveThe 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).MethodsBangladeshi 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.ResultsIn 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).ConclusionResults 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.

Cold Extrusion but Not Coating Affects Iron Bioavailability from Fortified Rice in Young Women and Is Associated with Modifications in Starch Microstructure and Mineral Retention during Cooking

Background: Rice can be fortified with the use of hot or cold extrusion or coating, but the nutritional qualities of the resulting rice grains have never been directly compared.Objective: Using fortified rice produced by coating or hot or cold extrusion, we compared 1) iron and zinc absorption with the use of stable isotopes, 2) iron and zinc retention during cooking, and 3) starch microstructure.Methods: We conducted 2 studies in young women: in study 1 [n = 19; mean ± SD age: 26.2 ± 3.4 y; body mass index (BMI; in kg/m2): 21.3 ± 1.6], we compared the fractional iron absorption (FAFe) from rice meals containing isotopically labeled ferric prophosphate (57FePP), zinc oxide (ZnO), citric acid, and micronutrients fortified through hot extrusion (HER1) with rice meals fortified through cold extrusion containing 57FePP, ZnO, citric acid, and micronutrients (CER); in study 2 (n = 22; age: 24 ± 4 y; BMI: 21.2 ± 1.3), we compared FAFe and fractional zinc absorption (FAZn) from rice meals fortified through hot extrusion (HER2) compared with rice meals fortified through coating containing 57FePP, ZnO, a citric acid and trisodium cirate mixture (CA/TSC), and micronutrients (COR) relative to rice meals extrinsically fortified with ferrous sulfate (reference). Rice types HER1 and CER contained citric acid, whereas types HER2 and COR contained CA/TSC. We assessed retention during standardized cooking experiments and characterized the rice starch microstructure.Results: FAFe (95% CI) was greater from CER [2.2% (1.4%, 3.4%)] than from HER1 [1.2% (0.7%, 2.0%)] (P = 0.036). There was no difference in FAFe between HER2 [5.1% (3.7%, 7.1%)] and COR [4.0% (2.9%, 5.4%)] (P = 0.14), but FAFe from COR was lower than that from the reference meal [6.6% (4.9%, 9.0%)] (P = 0.003), and the geometric mean FAZn (95% CI) did not differ between HER2 [9.5% (7.9%, 11.6%)] and COR [9.6% (8.7%, 10.7%)] (P = 0.92). Cooking in a rice-to-water ratio of 1:2 resulted in iron and zinc retentions >80%, and cooking in excess water did not affect iron retention from hot-extruded rice but caused iron losses of 25% from CER and COR. Distinct variations in starch microstructure were found in CER and HER1.Conclusions: Iron absorption was 64% higher from CER than from hot-extruded rice, with no difference between COR compared with hot-extruded rice. Lower extrusion temperatures may generate a more readily digestible starch structure, allowing for greater iron release in vivo but lower mineral retention during cooking. This trial was registered at clinicaltrials.gov as NCT02176759.

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).

Supplemental Zinc Decreases Fractional Zinc Absorption and Increases Lean Tissue Mass among Vietnamese Children with Tuberculosis

Childhood tuberculosis (TB) is a major health concern in Vietnam. Dietary Zn absorption is greater in children recovering from TB, possibly due to increased demand of Zn for immune function. Zn supplementation, therefore, may improve the effectiveness of TB treatment. Our objective was to determine changes in Zn homeostasis in response to Zn supplements among children admitted for treatment of TB at the National Lung Hospital in Hanoi, Vietnam.After baseline, children matched by sex were randomized to 10 mg Zn/d (n=10) or placebo (n=11) for the first 2 mo of TB treatment. At baseline and after 2 mo, fractional Zn absorption (FZA) and exchangeable Zn pool size (EZP) were determined using Zn stable isotopes during an 8 d controlled‐diet metabolic study. After each of 3 meals on d 2, the child received 0.33 mg 67Zn orally and, 1 h following dinner, 0.1 mg 70Zn intravenously. FZA was determined from urinary Zn tracer‐tracee ratios (TTRs) in samples collected 5–7 d post isotope administration. EZP was estimated from the y‐intercept of the log‐transformed linear regression of urinary 70Zn TTRs. Height, weight, body mass index (BMI), mid‐upper arm circumference (MUAC), triceps skinfold thickness (TSK), and subscapular skinfold thickness (SSK) were determined. Mid‐upper arm muscle area (MUAM) and mid‐upper arm fat area (MUAF) were derived from MUAC and TSK.21 children 9 to 15 y, 11 male and 10 female, enrolled. 14 had pulmonary TB. Height‐ and BMI‐for‐age z‐scores were −1.2 (−1.9, −0.6) and −1.7 (−2.4, −1.0), respectively. After 2 mo, controlling for baseline values, FZA was significantly lower among Zn‐supplemented children vs. placebo: 25.8% (21.5, 30.1%) vs. 32% (27.7, 36.3%), p &lt; 0.05. EZP tended to be higher with Zn compared with placebo: 83.3 mg (69.2, 97.5 mg) vs. 70.1 mg (55.2, 85 mg), p = 0.19 (NS). No differences in weight, height, or BMI were observed. MUAC was higher among Zn supplemented, 21.1 cm (20.2, 22 cm), vs. placebo, 19.5 cm (18.7, 20.3 cm), p &lt; 0.05. MUAM was also higher among Zn supplemented, 19.6 cm2 (17.3, 22.2 cm2) vs. 15.7 cm2 (13.9, 17.6 cm2) placebo, p &lt; 0.05.In sum, 10 mg Zn/d led to a homeostatic response and improved lean tissue gain in Vietnamese children with TB, and thus should further be evaluated as part of their treatment. Given the sensitivity of MUAC and MUAM, these indicators should be included for monitoring the TB recovery process in future studies.Support or Funding InformationInternational Atomic Energy Agency, Contract 15859

Effect of phytase on zinc absorption from a millet-based porridge fed to young Burkinabe children

Fortifying cereal staples with zinc is a strategy for increasing zinc intake in young children in developing countries. However, phytic acid (PA) naturally present in cereals strongly decreases zinc absorption. A stable-isotope zinc absorption study was conducted in young children to investigate the ability of the PA-degrading enzyme phytase to improve zinc absorption, when added to a cereal porridge immediately before consumption. Fractional absorption of zinc (FAZ) was estimated in 35 young healthy Burkinabe children using the double-isotopic tracer ratio method with 67Zn as oral tracer and 70Zn as intravenous tracer, in a crossover design. The test meals were: (a) a millet-based porridge containing 1.4 mg total zinc (native plus 1 mg added as ZnSO4) with a PA:Zn molar ratio of 7.7; (b) the same porridge with the enzyme phytase (20.5 phytase units (FTU)) added immediately before consumption. The exchangeable zinc pool (EZP) was determined as a potential measure of long-term zinc intake in 20 of the 35 children and compared with FAZ. Mean FAZ increased from 9.5±3.4 to 16.0±5.1% (P<0.0001), when phytase was added to the meal. The mean EZP was 3.6±0.5 mg/kg. There was no correlation between the EZP and FAZ values for either of the two test meals. Adding phytase immediately prior to consumption of a zinc-fortified cereal-based complementary food can improve zinc absorption in young children.

Fractional Zinc Absorption for Men, Women, and Adolescents Is Overestimated in the Current Dietary Reference Intakes

Background: The fractional zinc absorption values used in the current Dietary Reference Intakes (DRIs) for zinc were based on data from published studies. However, the inhibitory effect of phytate was underestimated because of the low phytate content of the diets in the studies used.Objective: The objective of this study was to estimate the fractional absorption of dietary zinc from the US diet by using 2 published algorithms.Methods: Nutrient intake data were obtained from the NHANES 2009–2010 and the corresponding Food Patterns Equivalents Database. Data were analyzed with the use of R software by taking into account the complex survey design. The International Zinc Nutrition Consultative Group (IZiNCG; Brown et al. Food Nutr Bull 2004;25:S99–203) and Miller et al. (Br J Nutr 2013;109:695–700) models were used to estimate zinc absorption.Results: Geometric means (95% CIs) of zinc absorption for all subjects were 30.1% (29.9%, 30.2%) or 31.3% (30.9%, 31.6%) with the use of the IZiNCG model and Miller et al. model, respectively. For men, women, and adolescents, absorption values obtained in this study with the use of the 2 models were 27.2%, 31.4%, and 30.1%, respectively, for the IZiNCG model and 28.0%, 33.0%, and 31.6%, respectively, for the Miller et al. model, compared with the 41%, 48%, and 40%, respectively, used in the current DRIs. For preadolescents, estimated absorption values (31.1% and 32.8% for the IZiNCG model and Miller et al. model, respectively) compare well with the conservative estimate of 30% used in the DRIs. When the new estimates of zinc absorption were applied to the current DRI values for men and women, the results suggest that the Estimated Average Requirement (EAR) and RDA for these groups need to be increased by nearly one-half of the current values in order to meet their requirements for absorbed zinc.Conclusions: These data suggest that zinc absorption is overestimated for men, women, and adolescents in the current DRI. Upward adjustments of the DRI for these groups are recommended.

Zinc Absorption by Adults Is Similar from Intrinsically Labeled Zinc-Biofortified Rice and from Rice Fortified with Labeled Zinc Sulfate

Biofortification of staple food crops is a promising strategy to combat zinc deficiency, and it is of particular interest for rice and crops that are not consumed as flours and therefore not suitable for postharvest fortification. Because zinc absorption is decreased by phytic acid (PA) and perhaps other dietary components, it is important to measure the absorption of zinc from a biofortified crop before determining its efficacy. In this study, we compared the zinc absorption from zinc-biofortified rice (hydroponically enriched with (70)Zn) with that from a control rice of the same variety fortified with (70)ZnSO4 at point of use to reach the same total zinc content of 1.1 mg/meal. Both rice meals had a PA:Zn molar ratio of 12. Fractional absorption of zinc (FAZ) was measured with the use of the double-isotope tracer ratio method in 16 apparently healthy adults [18-45 y old; BMI (in kg/m(2)) 19-25] who consumed 2 single meals at 4-wk intervals in random order in a crossover design. The FAZ from the biofortified rice (mean ± SD: 25.1 ± 8.7%) did not differ significantly from that of the point-of-use fortified rice (mean ± SD: 20.8 ± 7.1%) (P = 0.08). These results suggest that the native zinc accumulated in the biofortified rice was readily released from the rice matrix and that its absorption by adults was influenced by PA and other food components in a similar way to the inorganic zinc compound added to the rice at point of use. Moreover, rice biofortification is likely to be as good as postharvest zinc fortification as an intervention strategy to combat zinc deficiency. This trial was registered at clinicaltrials.gov as NCT01633450.

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

Zinc deficiency and contaminated water are major contributors to diarrhea in developing countries. Food fortification with zinc has not shown clear benefits, possibly because of low zinc absorption from inhibitory food matrices. We used a novel point-of-use water ultrafiltration device configured with glass zinc plates to produce zinc-fortified, potable water. The objective was to determine zinc bioavailability from filtered water and the efficacy of zinc-fortified water in improving zinc status. In a crossover balanced study, we measured fractional zinc absorption (FAZ) from the zinc-fortified water in 18 healthy Swiss adults using zinc stable isotopes and compared it with zinc-fortified maize porridge. We conducted a 20-wk double-blind randomized controlled trial (RCT) in 277 Beninese school children from rural settings who were randomly assigned to receive a daily portion of zinc-fortified filtered water delivering 2.8 mg Zn (Zn+filter), nonfortified filtered water (Filter), or nonfortified nonfiltered water (Pump) from the local improved supply, acting as the control group. The main outcome was plasma zinc concentration (PZn), and the 3 groups were compared by using mixed-effects models. Secondary outcomes were prevalence of zinc deficiency, diarrhea prevalence, and growth. Geometric mean (-SD, +SD) FAZ was 7-fold higher from fortified water (65.9%; 42.2, 102.4) than from fortified maize (9.1%; 6.0, 13.7; P < 0.001). In the RCT, a significant time-by-treatment effect on PZn (P = 0.026) and on zinc deficiency (P = 0.032) was found; PZn in the Zn+filter group was significantly higher than in the Filter (P = 0.006) and Pump (P = 0.025) groups. We detected no effect on diarrhea or growth, but our study did not have the duration and power to detect such effects. Consumption of filtered water fortified with a low dose of highly bioavailable zinc is an effective intervention in children from rural African settings. Large community-based trials are needed to assess the effectiveness of zinc-fortified filtered water on diarrhea and growth. These trials were registered at clinicaltrials.gov as NCT01636583 and NCT01790321.

Whey‐Based Supplement Added to a Plant‐Based Diet Increases Total Zinc Absorption, but not Total Iron in Mexican Children.

The objective of the present study was to determine the effect of a whey‐based nutritional supplement (WPS) on zinc and iron absorption from a plant‐based diet (PBD) in Mexican children. Study 1 evaluated zinc absorption in a cross‐over design. Children (n=16) were randomly assigned to receive the PBD with and without WPS on days 1 and 2 and urine samples were collected on days 1 and 6 to 9 to measure zinc absorption. Study 2 evaluated iron absorption in a parallel study. Children were randomly assigned to one of two experimental groups. Group 1 consumed the PBD during 2 days (n=16) and group 2 consumed the PBD + WPS during 2 days (n=16). A reference dose of iron was consumed with 25 mg of ascorbic acid the first day. Blood samples were collected at baseline and 14 d after the last dose was given. Zinc and iron absorption were measured using 70Zn, 68Zn, 58Fe and 57Fe isotopes. Fractional absorption of zinc was similar in both the PBD and the PBD+WPS groups (0.09±0.03 vs 0.09±0.04 mg). Because total dietary zinc was significantly higher when receiving WPS, the total amount of zinc absorbed was higher compared to PBD alone (5.2±1.1 vs2.8±0.9 mg; p&lt;0.05). No differences were observed between groups in fractional absorption of iron, adjusted iron absorption or total absorbed iron between groups. With the simultaneous intake of WPS, fractional absorption of zinc and iron from a PBD is maintained and total absorption of zinc was increased. Partially supported by IAEA.

Milk Enhances In Vitro Accessibility and Fractional Absorption of Zinc (FAZ) from High Phytate Intrinsically Labelled Rice in Humans

Milk Enhances In Vitro Accessibility and Fractional Absorption of Zinc (FAZ) from High Phytate Intrinsically Labelled Rice in Humans

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.