Zinc Fortification Research Articles

Zinc Fortification of Oat Grains Through Zinc Fertilisation

A two-year study at the Indian Agricultural Research Institute, New Delhi showed that an increase in grain and straw yields and zinc (Zn) fortification of grains of oats is possible by Zn fertilisation. Zn fertilisation is the fastest way to fortify oat grains with Zn, which is wanting in human and animal nutrition, especially in developing countries. Zn fortification of oats deserves special attention, because oat is gaining importance as a healthy cereal for human consumption. Coating oat seeds with Zn sulphate or Zn oxide before sowing was found to be the best method from the viewpoint of grain and straw yields as well as Zn fortification of oat grains. The next best method was deep placement of Zn fertilisers at sowing.

Effect of Increasing Levels of Zinc Fortificant on the Iron Absorption of Bread Co-Fortified with Iron and Zinc Consumed with a Black Tea

Iron (Fe) and zinc's (Zn) interaction at the absorptive level can have an effect on the success of co-fortification of wheat flour with both minerals on iron deficiency prevention. The aim of the study was to determine the effect of increasing levels of zinc fortificant on the iron absorption of bread co-fortified with iron and zinc consumed with a black tea. Twelve women aged 33-42 years participated in the study. They received on four different days 200 mL of black tea and 100 g of bread made with wheat flour (70% extraction) fortified with either 30 mg Fe/kg alone, as ferrous sulfate (A), or with the same Fe-fortified flour, but with graded levels of Zn, as zinc sulfate: 30 mg/kg (B), 60 mg/kg (C), or 90 mg/kg (D). Fe radioisotopes ((59)Fe and (55)Fe) of high specific activity were used as tracers, and Fe absorption iron was measured by the incorporation of radioactive Fe into erythrocytes. The geometric mean and range of ±1 SD of Fe absorption were as follows: A = 6.5% (2.2-19.3%), B = 4.6% (1.0-21.0%), C = 2.1% (0.9-4.9%), and D = 2.2% (0.7-6.6%), respectively; ANOVA for repeated measures F = 10.9, p < 0.001 (Scheffè's post hoc test: A vs. C, A vs. D, B vs. C, and B vs. D; p < 0.05). We can conclude that Fe absorption of bread made from low-extraction flour fortified with 30 mg/kg of Fe, as ferrous sulfate, and co-fortified with zinc, as zinc sulfate consumed with black tea is significantly decreased at a zinc fortification level of ≥60 mg/kg flour.

Associations among Dietary Zinc Intakes and Biomarkers of Zinc Status before and after a Zinc Supplementation Program in Guatemalan Schoolchildren

The associations among dietary zinc intakes and biomarkers of zinc status are unknown in apparently healthy children at high risk for zinc deficiency. To assess associations among zinc-related parameters in a sample of Guatemalan school-aged children. We assessed total dietary intakes and biomarkers of zinc status before and after receiving 6 months of zinc supplementation or placebo in 691 Guatemalan schoolchildren aged 6 to 11 years. Most of the children also received zinc-fortified milk from a government program that started shortly after the trial began. We assessed associations between zinc intakes and serum zinc, alkaline phosphatase (ALP), and albumin. At baseline, the prevalence of serum zinc < 65 microg/dL and dietary zinc intake below Estimated Average Requirements (EAR) (< 4 and < 7 mg/day for children < 9 and > or = 9 years, respectively) were 21.6% and 39.4%, respectively. Pearson correlations between serum zinc concentration and dietary zinc intake, serum ALP, and serum albumin were r = 0.07, 0.15, and 0.07, respectively. At the 6-month follow-up, low serum zinc and low total (diet plus fortified milk) zinc intakes were observed in 1.2% and 0.0% of children in the zinc-supplemented group and 4.0% and 34.1% in the placebo group, respectively. Pearson correlations between serum zinc concentration and total zinc intake, serum ALP, and serum albumin were 0.10, 0.06, and -0.11 in the zinc-supplemented group and -0.04, 0.05, and 0.01 in the placebo group, respectively. Zinc intake was inconsistently associated with markers of serum zinc concentration. Zinc fortification or supplementation attenuated the associations.

Zinc uptake by lactic Acid bacteria.

The study aims to investigate zinc biosorption by strains of lactobacilli and bifidobacteria with a view to exploit them as organic matrixes for zinc dietary supplementation. Sixteen human strains of Lactobacillus and Bifidobacterium were assayed for zinc uptake. The minimum inhibitory concentration of zinc salts differed among the strains, but was never below 15 mmol L−1. When cultured in MRS broth containing 10 mmol L−1 ZnSO4, all the strains were capable of accumulating zinc in the range between 11 and 135 μmol g−1. The highest amount of cell-bound zinc was obtained in L. acidophilus WC 0203. pH-controlled batch cultures of this strain revealed that zinc uptake started in the growth phase, but occurred mostly during the stationary phase. Pasteurized and viable cultures accumulated similar amount of zinc, suggesting that a nonmetabolically mediated mechanism is involved in zinc uptake. These results provide new perspectives on the specific use of probiotics, since L. acidophilus WC 0203 could function as an organic matrix for zinc incorporation. The bioavailability of Lactobacillus-bound zinc deserves to be investigated to provide a future basis for optimization of zinc supplementation or fortification.

New approaches for correcting zinc deficiency without zinc fortification

New approaches for correcting zinc deficiency without zinc fortification

Effect of zinc fortification on Cheddar cheese quality

Zinc-fortified Cheddar cheese containing 228mg of zinc/kg of cheese was manufactured from milk that had 16mg/kg food-grade zinc sulfate added. Cheeses were aged for 2 mo. Culture activity during cheese making and ripening, and compositional, chemical, texture, and sensory characteristics were compared with control cheese with no zinc sulfate added to the cheese milk. Compositional analysis included fat, protein, ash, moisture, zinc, and calcium determinations. The thiobarbituric acid (TBA) assay was conducted to determine lipid oxidation during aging. Texture was analyzed by a texture analyzer. An untrained consumer panel of 60 subjects evaluated the cheeses for hardness, off-flavors, appearance, and overall preference using a 9-point hedonic scale. Almost 100% of the zinc added to cheese milk was recovered in the zinc-fortified cheese. Zinc-fortified Cheddar cheese had 5 times more zinc compared with control cheese. Zinc-fortified cheese had higher protein and slightly higher fat and ash contents, whereas moisture was similar for both cheeses. Zinc fortification did not affect culture activity during cheese making or during the 2-mo aging period. The TBA value of control cheese was higher than that of zinc-fortified cheese at the end of ripening. Although zinc-fortified cheese was harder as determined by the texture analyzer, the untrained consumer panel did not detect differences in the sensory attributes and overall quality of the cheeses. Fortification of 16mg/kg zinc sulfate in cheese milk is a suitable approach to fortifying Cheddar cheese without changing the quality of Cheddar cheese.

Response of lactic acid bacteria to milk fortification with dietary zinc salts

Zinc is essential for many basic physiological functions in humans. The human body has a limited zinc storage capacity; zinc deficiency can develop rapidly when intakes are low. Food fortification is a successful strategy to control zinc deficiency. Very little information is available about the response of lactic acid bacteria (LAB) to milk fortified with different zinc salts. In this study, the acidifying activity of 98 LAB cultures in reconstituted skim milk fortified with zinc aspartate, zinc sulphate or zinc gluconate was assessed. Based on the overall results, a strain-dependent response was seen irrespective of the zinc source. The cultures with the best performance in terms of acidification rate and acidification extent were used for the formulation of multi-strain starters destined for the manufacture of two zinc-reinforced Italian cheeses (Squacquerone and Caciotta). The cheese-making trials showed that zinc fortification had no impact on the main properties of the cheeses.

Plasma Zinc Concentration Increases within 2 Weeks in Healthy Senegalese Men Given Liquid Supplemental Zinc, but Not Zinc-Fortified Wheat Bread

The responsiveness of plasma zinc concentration to zinc fortification is uncertain. Our objective in this study was to determine whether plasma zinc concentration changes in response to consuming zinc-fortified foods or liquid zinc supplements. We conducted a 4-wk double-blind, randomized trial among 132 healthy Senegalese men ≥ 18 y. Participants received 1 of 4 interventions: 1) (control) 200 g/d of wheat bread fortified with iron and folic acid, but not zinc, and a liquid multivitamin supplement without zinc between meals; 2) (zinc supplement) the same bread and the same multivitamin supplement with 15 mg zinc as ZnSO(4) added; 3) (moderate zinc fortification) the same bread cofortified with 7.5 mg zinc as ZnO and the same multivitamin supplement without zinc; or 4) (high zinc fortification) the same bread cofortified with 15 mg zinc as ZnO and the same multivitamin supplement without zinc. Fasting blood samples were collected twice at baseline and at d 15 and 29 of the intervention. There was no significant interaction between group and study day (P = 0.11). However, at d 15, the mean change in plasma zinc concentration in the zinc-supplemented group was greater than in the placebo and fortification groups ( 0.72 μmol/L vs. -0.09 to 0.03 μmol/L; P = 0.05). At d 29 there were no significant group-wise differences. Across all time points, the zinc-supplemented group was the only group where plasma zinc concentration increased from baseline (P = 0.006). These results suggest that plasma zinc concentration may not be a sufficiently sensitive indicator to evaluate short-term responses to zinc fortification.

Plasma zinc concentration responds to short-term zinc supplementation, but not zinc fortification, in young children in Senegal

Simple, low-cost methods are needed to evaluate the effect of zinc-fortification programs. Plasma zinc concentration is a useful biomarker of zinc intake from supplementation, but responses to zinc fortification are inconsistent. The objective was to compare the change in plasma zinc concentrations in young children who received zinc from either a liquid supplement or a zinc-fortified complementary food. A double-blind intervention trial was conducted in 137 young Senegalese children aged 9-17 mo who were randomly assigned to receive one of the following treatments for 15 d: 1) 30 g dry weight of an iron-fortified cereal porridge and a liquid multivitamin supplement without zinc (control group), 2) the same porridge and multivitamin supplement with 6 mg Zn added to the supplement dose (ZnSuppl group), or 3) the same porridge with added zinc to provide 6 mg Zn per 25 g dry weight of porridge and multivitamin without zinc (ZnFort group). Mean (±SD) plasma zinc concentration (μg/dL) increased by 4.7 ± 1.6 (P = 0.004) in the ZnSuppl group, which was significantly greater (P = 0.009) than the mean change in the control group (-1.0 ± 1.6; P = 0.51) and in the ZnFort group (-1.8 ± 1.7; P = 0.29). The latter 2 groups did not differ from each other (P = 0.99). Plasma zinc concentration increased in children who received daily zinc supplementation for 15 d but not in those who received a zinc-fortified complementary food containing a similar amount of zinc. Additional longer-term studies are needed to assess the effect of zinc-fortification programs on zinc-related functional outcomes and the usefulness of plasma zinc as a biomarker of program effect. This trial was registered at www.clinicaltrials.gov as study NCT0094398.

Effect of Zinc and Iron Fortification of the Feed on Liver and Thyroid Function in Rats

Changes in plasma glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), triiodothyronine (T3), and thyroxin (T4) of male rats, following 8weeks of administration of different concentrations of elemental iron (EI), sodium iron ethylenediaminetetraacetate (NaFeEDTA), zinc sulfate (ZnSO(4)), and zinc oxide (ZnO) in whole wheat flour were investigated. Liver enzymes and thyroid hormones were determined using colorimetric methods and enzyme immune assay, respectively. Ingestion of fortified diets by the male rats did not show a marked effect on GOT and GPT, the exception being NaFeEDTA fed alone and EI with ZnO-fortified diets indicating a significant (p < 0.05) decrease in GOT levels in rats. Similarly, only NaFeEDTA significantly (p < 0.05) increased thyroxin, while EI, ZnSO(4), and ZnO either alone or in any combination did not alter thyroid secretions. Changes in GOT, GPT, T3, and T4 levels, as a result of ingesting iron and zinc-fortified diets by rats, ranged in the safe limits.

Acceptability of Complementary Foods and Breads Prepared from Zinc‐Fortified Cereal Flours among Young Children and Adults in Senegal

We completed a series of studies to assess the acceptability of zinc-fortified, cereal-based complementary foods and zinc-fortified wheat breads. Young children and their caregivers completed acceptability tests with complementary foods fortified with iron only (60 mg iron as ferrous fumarate per kilogram cereal flour), or the same level of iron and zinc (240 mg zinc as zinc oxide per kilogram cereal flour), and the caregivers completed triangle taste tests to compare the same products. A separate group of adult participants completed acceptability tests with wheat breads fortified with iron and folic acid (15 mg iron as ferrous fumarate per kilogram flour and 1.5 mg folic acid per kilogram flour) or the same levels of iron-folic acid and 2 levels of zinc (63 mg zinc or 126 mg zinc as zinc oxide per kilogram flour). Finally, a threshold test was administered to another group of adult participants to compare nonfortified wheat bread to breads fortified with zinc in 80 mg increments ranging from 80 to 400 mg zinc as zinc oxide per kilogram flour. All products were acceptable when compared to non-zinc-fortified equivalents, and were well liked by the respective participants. For the triangle tests, caregivers were not able to detect significant differences between products. For threshold tests, adult participants detected differences in breads prepared from fortified wheat flour at 80 mg, 160 mg, and 320 mg zinc per kilogram flour, but not at 240 mg and 400 mg zinc per kilogram flour, respectively, when compared to nonfortified bread equivalents. Zinc fortification of cereal flours in the ranges of fortification that were tested does not adversely affect the acceptability of complementary foods and breads prepared from these flours. Practical Application: Fortification of staple food products is a low-cost approach to deliver additional micronutrients (including zinc) to large segments of a population. Determining the acceptability of products fortified with zinc is an important step in the development of zinc fortification programs.

Iron Fortification of Banana by the Expression of Soybean Ferritin

Iron deficiency anemia is one of the serious ailments related to nutrition in the developing countries. Fruit and vegetable crops favor the bioavailability of iron. Banana is consumed as a staple food in the tropics. Iron-fortified bananas provide an effective means of controlling the iron deficiency. Embryogenic cells of banana cv. Rasthali (AAB) were transformed with soybean ferritin cDNA using two different expression cassettes pSF and pEFE-SF to express ferritin. Transgenic nature of the regenerated plants was confirmed by PCR. Transgenic plants were regenerated and analyzed through PCR and PCR-Southern analysis. The expression of ferritin was confirmed by RT-PCR. Iron and zinc levels in the transgenic and control plants were estimated by atomic absorption spectroscopy. A 6.32-fold increase in iron accumulation and a 4.58-fold increase in the zinc levels were noted in the leaves of transgenic plants. Thus, iron- and zinc-fortified bananas could be developed as a functional food to overcome the malnutrition-related iron deficiency. This is the first report on the iron and zinc fortification of banana.

Zinc Fortification of Cereal Flours: Current Recommendations and Research Needs

Zinc fortification is recommended as an appropriate strategy to enhance population zinc status, but guidelines are needed on the appropriate types and levels of zinc fortification of cereal flours for mass fortification programs. To review available information on the scientific rationale, efficacy, and effectiveness of zinc fortification programs, and to develop guidelines on appropriate levels of fortification of cereal flours, based on simulations of the amount of zinc absorbed under different dietary conditions and information on possible adverse effects. Systematic review of scientific literature and application of an existing prediction equation to estimate zinc absorption. Previously completed research demonstrates that zinc intake and absorption are increased when zinc-fortified foods are consumed, but little information is, as yet, available on the biologic impact of large-scale fortification programs. Studies suggest that there are no disadvantages of the recommended ranges of zinc fortification with regard to the sensory properties of zinc-fortified foods, and most research indicates that there are no adverse effects of zinc fortification on the utilization of other minerals. Zinc fortification of cereal flour is a safe and appropriate strategy for enhancing the zinc status of population subgroups who consume adequate amounts of fortified cereal flour, although additional information is needed to confirm the efficacy and effectiveness of large-scale zinc fortification programs to control zinc deficiency. The appropriate level of fortification depends on the population subgroup, their usual amount of flour intake, the degree of milling and fermentation that is practiced, and the usual intakes of zinc and phytate from other food sources. Fortification recommendations are presented for different dietary scenarios.

Zinc fortification of whole rice grain through parboiling process

The present study evaluated the effectiveness of zinc (Zn) fortification in a parboiling process for improving Zn density in parboiled-polished rice and its potential bioavailability in the human diet. Fortification of Zn in whole paddy rice grain with 50–400 mg Zn/kg paddy rice, during parboiling, increased Zn concentrations in polished-parboiled rice from 1.3 to 4.5 times those in unfortified parboiled rice. The added Zn rapidly penetrated into parboiled rice grains in the initial soaking process before saturation. There was an exponential correlation between Zn concentrations in unpolished ( r = 0.63) ( p < 0.01) and polished rice ( r = 0.30) ( p < 0.05) and soaking time. Zinc concentrations in unpolished rice were linearly correlated with Zn concentration in the polished rice ( r = 0.60) ( p < 0.01). Moreover, more than half of the added Zn is retained after a simulated washing process before cooking, ranging from 64–100%. In the Zn-fortified parboiled rice, 57–100% of Zn in polished rice grain was soluble in dilute acid, which was indicative of a high potential Zn bioavailability for human intake. The results suggest that parboiled rice has great potential for Zn fortification.

Finger millet ( Eleucine coracana) flour as a vehicle for fortification with zinc

Millets, being less expensive compared to cereals and the staple for the poorer sections of population, could be the choice for fortification with micronutrients such as zinc. In view of this, finger millet, widely grown and commonly consumed in southern India, was explored as a vehicle for fortification with zinc in this investigation. Finger millet flour fortified with either zinc oxide or zinc stearate so as to provide 50 mg zinc per kg flour, was specifically examined for the bioaccessibility of the fortified mineral, as measured by in vitro simulated gastrointestinal digestion procedure and storage stability. Addition of the zinc salts increased the bioaccessible zinc content by 1.5–3 times that of the unfortified flour. Inclusion of EDTA along with the fortified salt significantly enhanced the bioaccessibility of zinc from the fortified flours, the increase being three-fold. Inclusion of citric acid along with the zinc salt and EDTA during fortification did not have any additional beneficial effect on zinc bioaccessiblity. Moisture and free fatty acid contents of the stored fortified flours indicated the keeping quality of the same, up to 60 days. Both zinc oxide and zinc stearate were equally effective as fortificants, when used in combination with EDTA as a co-fortificant. The preparation of either roti or dumpling from the fortified flours stored up to 60 days did not result in any significant compromise in the bioaccessible zinc content. Thus, the present study has revealed that finger millet flour can effectively be used as a vehicle for zinc fortification to derive additional amounts of bioaccessible zinc, with reasonably good storage stability, to combat zinc deficiency.

Galvanizing Action: Conclusions and Next Steps for Mainstreaming Zinc Interventions in Public Health Programs

This paper summarizes the results of the foregoing reviews of the impact of different intervention strategies designed to enhance zinc nutrition, including supplementation, fortification, and dietary diversification or modification. Current evidence indicates a beneficial impact of such interventions on zinc status and zinc-related functional outcomes. Preventive zinc supplementation reduces the incidence of diarrhea and acute lower respiratory tract infection among young children, decreases mortality of children over 12 months of age, and increases growth velocity. Therapeutic zinc supplementation during episodes of diarrhea reduces the duration and severity of illness. Zinc fortification increases zinc intake and total absorbed zinc, and recent studies are beginning to confirm a positive impact of zinc fortification on indicators of population zinc status. To assist with the development of zinc intervention programs, more information is needed on the prevalence of zinc deficiency in different countries, and rigorous evaluations of the effectiveness of large-scale zinc intervention programs should be planned. Recommended steps for scaling up zinc intervention programs, with or without other micronutrients, are described. In summary, there is now clear evidence of the benefit of selected interventions to reduce the risk of zinc deficiency, and a global commitment is urgently needed to conduct systematic assessments of population zinc status and to develop interventions to control zinc deficiency in the context of existing public health and nutrition programs.

Impact of Zinc Fortification on Zinc Nutrition

Food fortification is increasingly recognized as an effective approach to improve a population's micronutrient status. The present report provides a critical review of the scientific evidence currently available on the impact of zinc fortification on zinc nutrition. The available studies clearly show that zinc fortification can increase dietary zinc intake and total daily zinc absorption. Most absorption studies also indicate that adding zinc to food does not adversely affect the absorption of other minerals, such as iron. Despite the positive effect of zinc fortification on total zinc absorption, only a few studies have found positive impacts of zinc fortification on serum zinc concentrations or functional indicators of zinc status. The reasons for these inconsistent results are uncertain but may relate to the choice of food vehicles, the age group and zinc status of the study populations, or particular aspects of the study design. Thus, additional research is needed to determine the impact of zinc fortification, with or without other micronutrients, in populations at risk for zinc deficiency. Because of the benefits of increasing intake in populations at high risk for zinc deficiency, the documented increase in total zinc absorption that occurs following zinc fortification, the absence of any adverse effects, and the relatively low cost of adding zinc, public health planners should consider including zinc in mass and targeted fortification programs in such populations. Because of the limited available information on program impact, it will be important to evaluate the outcomes of such programs.

Recent Advances in Knowledge of Zinc Nutrition and Human Health

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

Acute lower respiratory infections in childhood: opportunities for reducing the global burden through nutritional interventions.

Inadequate nutrition and acute lower respiratory infection (ALRI) are overlapping and interrelated health problems affecting children in developing countries. Based on a critical review of randomized trials of the effect of nutritional interventions on ALRI morbidity and mortality, we concluded that: (1) zinc supplementation in zinc-deficient populations prevents about one-quarter of episodes of ALRI, which may translate into a modest reduction in ALRI mortality; (2) breastfeeding promotion reduces ALRI morbidity; (3) iron supplementation alone does not reduce ALRI incidence; and (4) vitamin A supplementation beyond the neonatal period does not reduce ALRI incidence or mortality. There was insufficient evidence regarding other potentially beneficial nutritional interventions. For strategies with a strong theoretical rationale and probable operational feasibility, rigorous trials with active clinical case-finding and adequate sample sizes should be undertaken. At present, a reduction in the burden of ALRI can be expected from the continued promotion of breastfeeding and scale-up of zinc supplementation or fortification strategies in target populations.

Treatment of zinc deficiency without zinc fortification

Zinc (Zn) deficiency in animals became of interest until the 1950s. In this paper, progresses in researches on physiology of Zn deficiency in animals, phytate effect on bioavailability of Zn, and role of phytase in healing Zn deficiency of animals were reviewed. Several studies demonstrated that Zn is recycled via the pancreas; the problem of Zn deficiency was controlled by Zn homeostasis. The endogenous secretion of Zn is considered as an important factor influencing Zn deficiency, and the critical molar ratio is 10. Phytate (inositol hexaphosphate) constituted up to 90% of the organically bound phosphorus in seeds. Great improvement has been made in recent years on isolating and measuring phytate, and its structure is clear. Phytate is considered to reduce Zn bioavailability in animal. Phytase is the enzyme that hydrolyzes phytate and is present in yeast, rye bran, wheat bran, barley, triticale, and many bacteria and fungi. Zinc nutrition and bioavailability can be enhanced by addition of phytase to animal feeds. Therefore, using phytase as supplements, the most prevalent Zn deficiency in animals may be effectively corrected without the mining and smelting of several tons of zinc daily needed to correct this deficiency by fortification worldwide.