The effect of zinc-supplemented bread consumption on school children with asymptomatic zinc deficiency

Effects of Foods Fortified with Zinc, Alone or Cofortified with Multiple Micronutrients, on Health and Functional Outcomes: A Systematic Review and Meta-Analysis

Seventeen per cent of the world's population is estimated to be at risk of inadequate zinc intake, which could in part be addressed by zinc fortification of widely consumed foods. We conducted a review of efficacy and effectiveness studies to ascertain the effect of zinc fortification [postharvest fortification of an industrially produced food or beverage; alone or with multiple micronutrients (MMN)] on a range of health outcomes. Previous reviews have required that the effect of zinc be isolated; because zinc is always cofortified with MMN in existing fortification programs, we did not impose this condition. Outcomes assessed were zinc-related biomarkers (plasma or serum, hair or urine zinc concentrations, comet assay, plasma fatty acid concentrations, and the proportion of and total zinc absorbed in the intestine from the diet), child anthropometry, morbidity, mortality, cognition, plasma or serum iron and copper concentrations, and for observational studies, a change in consumption of the food vehicle. Fifty-nine studies were included in the review; 54 in meta-analyses, totaling 73 comparisons. Zinc fortification with and without MMN increased plasma zinc concentrations (efficacy, n = 27: 4.68 μg/dL; 95% CI: 2.62-6.75; effectiveness, n = 13: 6.28 μg/dL; 95% CI: 5.03-7.77 μg/dL) and reduced the prevalence of zinc deficiency (efficacy, n = 11: OR: 0.76, 95% CI: 0.60-0.96; effectiveness, n = 10: OR: 0.45, 95% CI: 0.31-0.64). There were statistically significant increases in child weight (efficacy, n = 11: 0.43 kg, 95% CI: 0.11-0.75 kg), improvements in short-term auditory memory (efficacy, n = 3: 0.32 point, 95% CI: 0.13-0.50 point), and decreased incidence of diarrhea (efficacy, n = 3: RR: 0.79, 95% CI: 0.68-0.92) and fever (efficacy, n = 2: RR: 0.85, 95% CI: 0.74-0.97). However, these effects cannot be solely attributed to zinc. Our review found that zinc fortification with or without MMN reduced the prevalence of zinc deficiency and may provide health and functional benefits, including a reduced incidence of diarrhea.

The prevalence of zinc deficiency in 6-month to 12-year old children in Bandar Abbas in 2013

Background

Zinc deficiency is an important problem in children, especially in developing countries. Zinc supplements have beneficial effects on multiple factors, including treatment of growth retardation and hypogonadism, and they can be used as therapeutic and prophylactic agents against infection in children.

Objective

To determine the prevalence of zinc deficiency in 6-month to 12-year-old children in Bandar Abbas.

Methods

This study was done in Bandar Abbas in 2013. In this cross-sectional study, 583 children were evaluated after obtaining a written informed consent from their parents. Zinc levels < 6 μg/dl were defined as zinc deficiency, zinc levels of 80–66 μg/dl were defined as insufficient, and zinc levels of 80–115 μg/dl were defined as sufficient levels. SPSS software, version 20, descriptive statistics, the chi-squared test, and the t-test were used to analyze the data.

Results

Five hundred and eighty-three children with a mean age of 42.82±30.68 months participated in this study. Among the participants, 263 (45.1%) were females, and 320 (54.9%) were males. The prevalence of zinc deficiency was 17.5% in this study. Zinc deficiencies were reported in 67 males (20.94%) males and in 35 females (13.30%). Zinc deficiencies were more common in boys, and this difference was statistically significant (p=0.01).

Conclusion

The results of this study indicated that the prevalence of zinc deficiencies is high in Bandar Abbas and that it is more prevalent in males than in females. The children in this area should be screened for zinc deficiency. Future studies should focus on then treatment of zinc deficiency and its role in different aspects of children’s health.

Fortification of staple foods with zinc for improving zinc status and other health outcomes in the general population

BACKGROUND

Zinc deficiency is a global nutritional problem, particularly in children and women residing in settings where diets are cereal based and monotonous. It has several negative health consequences. Fortification of staple foods with zinc may be an effective strategy for preventing zinc deficiency and improving zinc-related health outcomes.

OBJECTIVES

To evaluate the beneficial and adverse effects of fortification of staple foods with zinc on health-related outcomes and biomarkers of zinc status in the general population.

SEARCH METHODS

We searched the following databases in April 2015: Cochrane Central Register of Controlled Trials (CENTRAL, Issue 3 of 12, 2015, the Cochrane Library), MEDLINE & MEDLINE In Process (OVID) (1950 to 8 April 2015), EMBASE (OVID) (1974 to 8 April 2015), CINAHL (1982 to April 2015), Web of Science (1900 to 9 April 2015), BIOSIS (1969 to 9 April 2015), POPLINE (1970 to April 2015), AGRICOLA, OpenGrey, BiblioMap, and Trials Register of Promoting Health Interventions (TRoPHI), besides regional databases (April 2015) and theses. We also searched clinical trial registries (17 March 2015) and contacted relevant organisations (May 2014) in order to identify ongoing and unpublished studies.

SELECTION CRITERIA

We included randomised controlled trials, randomised either at the level of the individual or cluster. We also included non-randomised trials at the level of the individual if there was a concurrent comparison group. We included non-randomised cluster trials and controlled before-after studies only if there were at least two intervention sites and two control sites. Interventions included fortification (central/industrial) of staple foods (cereal flours, edible fats, sugar, condiments, seasonings, milk and beverages) with zinc for a minimum period of two weeks. Participants were members of the general population who were over two years of age (including pregnant and lactating women) from any country.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies for inclusion, extracted data from included studies, and assessed the risk of bias of the included studies.

MAIN RESULTS

We included eight trials (709 participants); seven were from middle-income countries of Asia, Africa, Europe, and Latin America where zinc deficiency is likely to be a public health problem. Four trials compared the effect of zinc-fortified staple foods with unfortified foods (comparison 1), and four compared zinc-fortified staple foods in combination with other nutrients/factors with the same foods containing other nutrients or factors without zinc (comparison 2). The interventions lasted between one and nine months. We categorised most trials as having unclear or high risk of bias for randomisation, but low risk of bias for blinding and attrition. None of the studies in comparison 1 reported data on zinc deficiency.Foods fortified with zinc increased the serum or plasma zinc levels in comparison to foods without added zinc (mean difference (MD) 2.12 µmol/L, 95% confidence interval (CI) 1.25 to 3.00 µmol/L; 3 studies; 158 participants; low-quality evidence). Participants consuming foods fortified with zinc versus participants consuming the same food without zinc had similar risk of underweight (average risk ratio 3.10, 95% CI 0.52 to 18.38; 2 studies; 397 participants; low-quality evidence) and stunting (risk ratio (RR) 0.88, 95% CI 0.36 to 2.13; 2 studies; 397 participants; low-quality evidence). A single trial of addition of zinc to iron in wheat flour did not find a reduction in proportion of zinc deficiency (RR 0.17, 95% CI 0.01 to 3.94; very low-quality evidence). We did not find a difference in serum or plasma zinc levels in participants consuming foods fortified with zinc plus other micronutrients when compared with participants consuming the same foods with micronutrients but no added zinc (MD 0.03 µmol/L, 95% CI -0.67 to 0.72 µmol/L; 4 studies; 250 participants; low-quality evidence). No trial in comparison 2 provided information about underweight or stunting.There was no reported adverse effect of fortification of foods with zinc on indicators of iron or copper status.

AUTHORS' CONCLUSIONS

Fortification of foods with zinc may improve the serum zinc status of populations if zinc is the only micronutrient used for fortification. If zinc is added to food in combination with other micronutrients, it may make little or no difference to the serum zinc status. Effects of fortification of foods with zinc on other outcomes including zinc deficiency, children's growth, cognition, work capacity of adults, or on haematological indicators are unknown. Given the small number of trials and participants in each trial, further investigation of these outcomes is required.

Zinc supplements for preventing otitis media

BACKGROUND

Otitis media is inflammation of the middle ear and is usually caused by infection. It affects people of all ages but is particularly common in young children. Around 164 million people worldwide have long-term hearing loss caused by this condition, 90% of them in low-income countries. As zinc supplements prevent pneumonia in disadvantaged children, we wanted to investigate whether zinc supplements could also prevent otitis media.

OBJECTIVES

To evaluate whether zinc supplements prevent otitis media in adults and children of different ages.

SEARCH METHODS

We searched CENTRAL (2014, Issue 1), MEDLINE (1950 to February week 4, 2014) and EMBASE (1974 to March 2014).

SELECTION CRITERIA

Randomised, placebo-controlled trials of zinc supplements given at least once a week for at least a month for preventing otitis media.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility and methodological quality of the included trials and extracted and analysed data. We summarised results using risk ratios (RRs) or rate ratios for dichotomous data and mean differences (MDs) for continuous data. We combined trial results where appropriate.

MAIN RESULTS

No new trials were identified for inclusion in this update. We identified 12 trials for inclusion, 10 of which contributed outcomes data. There were a total of 6820 participants. In trials of healthy children living in low-income communities, two trials did not demonstrate a significant difference between the zinc-supplemented and placebo groups in the numbers of participants experiencing an episode of definite otitis media during follow-up (3191 participants); another trial showed a significantly lower incidence rate of otitis media in the zinc group (rate ratio 0.69, 95% confidence interval (CI) 0.61 to 0.79, n = 1621). A small trial of 39 infants undergoing treatment for severe malnutrition suggested a benefit of zinc for the mean number of episodes of otitis media (mean difference (MD) -1.12 episodes, 95% CI -2.21 to -0.03). Zinc supplements did not seem to cause any serious adverse events but a small minority of children were reported to have vomited shortly after ingestion of the supplements. The trial evidence included is generally of good quality, with a low risk of bias.

AUTHORS' CONCLUSIONS

Evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of five years living in low- and middle-income countries is mixed. There is some evidence of benefit in children being treated for marasmus (severe malnutrition), but this is based on one small trial and should therefore be treated with caution.

Micronutrient fortification of food and its impact on woman and child health: a systematic review

BACKGROUND

Vitamins and minerals are essential for growth and metabolism. The World Health Organization estimates that more than 2 billion people are deficient in key vitamins and minerals. Groups most vulnerable to these micronutrient deficiencies are pregnant and lactating women and young children, given their increased demands. Food fortification is one of the strategies that has been used safely and effectively to prevent vitamin and mineral deficiencies.

METHODS

A comprehensive search was done to identify all available evidence for the impact of fortification interventions. Studies were included if food was fortified with a single, dual or multiple micronutrients and impact of fortification was analyzed on the health outcomes and relevant biochemical indicators of women and children. We performed a meta-analysis of outcomes using Review Manager Software version 5.1.

RESULTS

Our systematic review identified 201 studies that we reviewed for outcomes of relevance. Fortification for children showed significant impacts on increasing serum micronutrient concentrations. Hematologic markers also improved, including hemoglobin concentrations, which showed a significant rise when food was fortified with vitamin A, iron and multiple micronutrients. Fortification with zinc had no significant adverse impact on hemoglobin levels. Multiple micronutrient fortification showed non-significant impacts on height for age, weight for age and weight for height Z-scores, although they showed positive trends. The results for fortification in women showed that calcium and vitamin D fortification had significant impacts in the post-menopausal age group. Iron fortification led to a significant increase in serum ferritin and hemoglobin levels in women of reproductive age and pregnant women. Folate fortification significantly reduced the incidence of congenital abnormalities like neural tube defects without increasing the incidence of twinning. The number of studies pooled for zinc and multiple micronutrients for women were few, though the evidence suggested benefit. There was a dearth of evidence for the impact of fortification strategies on morbidity and mortality outcomes in women and children.

CONCLUSION

Fortification is potentially an effective strategy but evidence from the developing world is scarce. Programs need to assess the direct impact of fortification on morbidity and mortality.

Zinc supplements for preventing otitis media

BACKGROUND

Otitis media (OM) is inflammation of the middle ear and is usually caused by infection. It affects people of all ages but is particularly common in young children. Around 164 million people worldwide have long-term hearing loss caused by this condition, 90% of them in low-income countries. As zinc supplements prevent pneumonia in disadvantaged children, we wanted to investigate whether zinc supplements could also prevent OM.

OBJECTIVES

To evaluate whether zinc supplements prevent OM in adults and children of different ages.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2012, Issue 1) which includes the Cochrane Acute Respiratory Infections Groups' Specialised Register, MEDLINE (1950 to February week 1, 2012) and EMBASE (1974 to February 2012).

SELECTION CRITERIA

Randomised, placebo-controlled trials of zinc supplements given at least once a week for at least a month for preventing OM.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility and methodological quality of the included trials and extracted and analysed data. We summarised results using risk ratios (RRs) or rate ratios for dichotomous data and mean differences (MDs) for continuous data. We combined trial results where appropriate.

MAIN RESULTS

We identified 12 trials for inclusion, 10 of which contributed outcomes data. There was a total of 6820 participants. In trials of healthy children living in low-income communities, two trials did not demonstrate a significant difference between the zinc supplemented and placebo groups in the numbers of participants experiencing an episode of definite OM during follow-up (3191 participants); another trial showed a significantly lower incidence rate of OM in the zinc group (rate ratio 0.69, 95% confidence interval (CI) 0.61 to 0.79, n = 1621). A small trial of 39 infants undergoing treatment for severe malnutrition suggested a benefit of zinc for the mean number of episodes of OM (mean difference (MD) -1.12 episodes, 95% CI -2.21 to -0.03). Zinc supplements did not seem to cause any serious adverse events but a small minority of children were reported to have vomited shortly after ingestion of the supplements. The trial evidence included is generally of good quality, with a low risk of bias.

AUTHORS' CONCLUSIONS

Evidence on whether zinc supplementation can reduce the incidence of OM in healthy children under the age of five years living in low- and middle-income countries is mixed. There is some evidence of benefit in children being treated for marasmus (severe malnutrition) but this is based on one small trial and should therefore be treated with caution.

Erythrocyte zinc levels in children with bronchial asthma

Zinc deficiency may be suspected to play a role in the pathogenesis, control, and severity of asthma because of its antioxidant, antiapoptotic, and anti-inflammatory effects. We aimed to investigate whether there was any relationship between erythrocyte zinc levels and childhood asthma. The erythrocyte zinc levels of 67 asthmatic and 45 healthy children were analyzed in this case-control study. The mean concentrations of erythrocyte zinc were 1215.8 ± 145.1 µg/dl in asthma patients and 1206.9 ± 119.5 µg/dl in controls with no significant difference (P = 0.472). The erythrocyte zinc level was below 1,000 µg/dl in 6 asthmatic patients (8.9%) and 2 control group patients (4.4%). There was no relationship between erythrocyte zinc levels and duration of follow-up, severity, and control of the asthma (P > 0.05). On the other hand, patients hospitalized for an asthma attack had significantly lower erythrocyte zinc levels compared with nonhospitalized patients and the control group (P = 0.000 and P = 0.004 respectively). This study's findings indicate that asthmatic children are not a risk group for zinc deficiency. We emphasize that checking zinc levels in children who are hospitalized for an asthma attack may be useful.

Plasma zinc concentration responds to short-term zinc supplementation, but not zinc fortification, in young children in Senegal1,2

BACKGROUND

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.

OBJECTIVE

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.

DESIGN

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).

RESULTS

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).

CONCLUSIONS

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.

Zinc fortification of cereal flours: current recommendations and research needs

BACKGROUND

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.

OBJECTIVE

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.

METHODS

Systematic review of scientific literature and application of an existing prediction equation to estimate zinc absorption.

RESULTS

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.

CONCLUSIONS

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 supplements for preventing otitis media

BACKGROUND

Otitis media (inflammation of the middle ear, usually caused by infection) affects people of all ages, but is particularly common in young children. Around 164 million people worldwide have long-term hearing loss caused by this condition, 90% of them in low-income countries. Because zinc supplements prevent pneumonia in disadvantaged children, we wondered whether they prevent otitis media.

OBJECTIVES

To evaluate whether zinc supplements prevent otitis media in adults and children of different ages.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which includes the Acute Respiratory Infection Groups' Specialised Register; MEDLINE (1950 to June Week 1 2009); and EMBASE (1974 to June 2009).

SELECTION CRITERIA

Randomised, placebo-controlled trials of zinc supplements given at least once a week for at least a month for preventing otitis media.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the eligibility and methodological quality of the included trials, extracted and analysed data and wrote the review. We summarised results using risk ratios or rate ratios for dichotomous data and mean differences for continuous data. We combined trial results where appropriate.

MAIN RESULTS

We identified 12 trials for inclusion, 10 of which contributed outcomes data. In trials of healthy children living in low-income communities, two trials did not demonstrate a significant difference between the zinc supplemented and placebo groups in the numbers of participants experiencing an episode of definite otitis media during follow up (3191 participants), while another trial showed a significantly lower incidence rate of otitis media in the zinc group (rate ratio 0.69, 95% confidence interval (CI) 0.61 to 0.79, n = 1621). A small trial of 39 infants undergoing treatment for severe malnutrition suggested a benefit of zinc on the mean number of episodes of otitis media (mean difference -1.12 episodes, 95% CI -2.21 to -0.03). Zinc supplements did not seem to cause any serious adverse events, but a small minority of children were reported to have vomited shortly after ingestion of the supplements.

AUTHORS' CONCLUSIONS

Evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of five years living in low- and middle-income countries is mixed. There is some evidence of benefit in children being treated for marasmus, but this is based on one small trial and should therefore be treated with caution.

Effects of zinc supplementation on parent and teacher behaviour rating scores in low socioeconomic level Turkish primary school children

OBJECTIVE

To determine the effect of zinc supplementation on behaviour in low-income school aged children.

DESIGN

Double-blind randomized, placebo controlled trial.

SETTING

Low-income district primary school in Turkey.

PARTICIPANTS

Third grade students in the school. Among 252 students, 226 participated and 218 completed the study.

INTERVENTION

Children in each class were randomized either to the study group to receive 15 mg/day elemental zinc syrup or to placebo group to receive the syrup without zinc for 10 weeks.

MAIN OUTCOME MEASURES

The change in Conner's Rating Scales for Teachers and Parents scores after supplementation.

RESULTS

The mean Conner's Rating Scale for Parents scores on attention deficit, hyperactivity, oppositional behaviour and conduct disorder decreased significantly in the study and placebo groups after supplementation (p < 0.01). The prevalence of children with clinically significant parent ratings on attention deficit (p = 0.01) and hyperactivity (p = 0.004) decreased in the study group while prevalence of oppositional behaviour (p = 0.007) decreased in the placebo group. In children of mothers with low education all mean Parents' scores decreased significantly (p < 0.01) in the study group while only hyperactivity scores decreased in the placebo group (p < 0.01). In this subgroup the prevalence of children with clinically significant scores for attention deficit, hyperactivity and oppositional behaviour decreased only in the study group (p < 0.05). There was no change in mean Teachers' scores.

CONCLUSION

In our study zinc supplementation decreased the prevalence of children with clinically significant scores for attention deficit and hyperactivity. The affect on behaviour was more evident in the children of low educated mothers.

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.

Serum zinc levels in children with acute gastroenteritis

BACKGROUND

The aim of the present study was to determine the serum zinc levels on admission and 7-10 days after clinical recovery from acute gastroenteritis of <8 days' duration.

METHODS

This prospective study included 82 infants aged 2-24 months who had no associated bacterial infection, chronic disease, prior antibiotic use, moderate or severe malnutrition or dysentery. Forty-one healthy children formed the control group.

RESULTS

The mean serum zinc level on admission (Zn1) was 11.85 +/- 2.83 micromol/L and at 7-10 days after recovery (Zn2) was 10.92 +/- 2.17 micromol/L; mean serum zinc level of the control group was 11.81 +/- 3.45 micromol/L. Zn2 was significantly lower than Zn1, but there was no statistical difference between the mean of the control group and Zn1 and Zn2. When dehydrated patients were excluded from the patient group, Zn1 and Zn2 did not differ. Although asymptomatic, 39% of the control group had low zinc. Serum zinc levels were not affected by sex, age, clinical characteristics of the patients or severity of gastroenteritis.

CONCLUSION

Serum zinc levels of the patients admitted with acute gastroenteritis without any other disease and without moderate or severe malnutrition were not affected by disease state. Gastroenteritis did not further decrease serum zinc levels in patients with asymptomatic or subclinical zinc deficiency.

Impact of zinc supplementation in children with acute diarrhoea in Turkey

OBJECTIVE

Zinc deficiency is prevalent in children in developing countries. Supplemental zinc provides therapeutic benefits in diarrhoea. Our aim was to evaluate the effect of daily zinc supplementation for 14 days on diarrhoea duration, severity, and morbidity in children.

METHODS

In a randomised, open label non-placebo controlled trial, we assessed the efficacy of providing zinc sulfate to 6-60 month old children with acute diarrhoea for 2 weeks followed by 3 months of morbidity surveillance. Children were randomly assigned to zinc (n = 150) and control (n = 130) groups and received 15-30 mg elemental zinc daily.

RESULTS

Supplemented children had significantly improved plasma zinc levels by day 14 of therapy. Zinc deficiency was observed in 2.6% of the treatment and 3.3% of the control group. The mean duration of diarrhoea after starting supplementation was 3.02+/-2 days in the zinc group and 3.67+/-3.2 days in the control group. There was no significant difference in diarrhoea duration by treatment group (p>0.05). The number of stools after starting supplementation was 5.8+/-3.7 and 5.1+/-3.9 on day 1, 2.9+/-1.6 and 3.0+/-2.2 on day 2, and 1.8+/-1.1 and 1.6+/-0.9 on day 3 in the zinc and control groups, respectively. There was no significant difference in diarrhoea severity by treatment group (p>0.05). No significant effect was found on the incidence and prevalence of diarrhoea in the zinc compared with the control group.

CONCLUSION

Our data indicate that supplementing children with acute diarrhoea in Turkey with 3 RDA of elemental zinc for 14 days improved neither diarrhoea duration nor severity despite significant increments in plasma zinc.

New approaches for designing and evaluating food fortification programs

Historically, food fortification programs were often undertaken with little attention to issues such as micronutrient bioavailability, optimal levels of addition, or efficacy or to monitoring impact on nutritional status, health, and human function. Several developments in recent years have enabled substantial progress to be made in the design and evaluation of fortification programs. The methodology for estimating the prevalence of inadequate nutrient intakes in a population and tolerable upper intake levels has been established and can be used as the basis for estimating desirable amounts of nutrient addition. More attention is being paid to assessing the bioavailability of nutrients (especially minerals) using stable and radioactive isotopes, and bioavailability of iron compounds can be estimated from changes in total body iron calculated from the ratio of transferrin receptors to serum ferritin. Procedures for quality control of the fortification process have been established. New approaches to monitoring the impact of fortification over time include assessment of liver retinol stores using retinol isotope dilution. In summary, the design and evaluation of food fortification programs now requires a series of formative research procedures on the part of nutritionists, which were not often expected or conducted in the past.

Effect of zinc supplementation on growth hormone secretion, IGF-I, IGFBP-3, somatomedin generation, alkaline phosphatase, osteocalcin and growth in prepubertal children with idiopathic short stature

Controversy exists about the effect of zinc on growth and the GH-IGF system. Zinc supplementation has been shown to stimulate linear growth in zinc-deficient children. However the mechanism of this effect has not been well characterized. Furthermore, the effect of zinc supplementation on non-zinc-deficient short children is unknown. We investigated the effect of zinc supplementation on endogenous GH secretion, serum IGF-I and IGFBP-3 concentrations, IGF-I and IGFBP-3 generation in response to exogenous GH, bone formation markers, and linear growth of non-zinc-deficient children with idiopathic short stature. We analyzed prospectively serum zinc, IGF-I, IGFBP-3, alkaline phosphatase, osteocalcin, and GH response to clonidine test, and performed a somatomedin generation test before and 6 weeks after zinc supplementation in 22 (16 M, 6 F) prepubertal children with idiopathic short stature. Serum IGF-I increased from 67.4+/-70.6 to 98.2+/-77.3 ng/ml (p <0.001), IGFBP-3 from 2326+/-770 to 2758+/-826 ng/ml (p <0.001), alkaline phosphatase from 525+/-136 to 666+/-197 U/l (p <0.0001), and osteocalcin from 16.8+/-10.6 to 25.8+/-12.8 ng/ml (p <0.05) after zinc supplementation despite there being no difference in GH response to clonidine after zinc supplementation (peak GH 11.6+/-6.9 vs 13.4+/-7.8 ng/ml, GH area under the curve during clonidine test 689+/-395 vs 761+/-468, NS). Percent change in IGF-I and IGFBP-3 during the somatomedin generation test was not significantly affected by zinc supplementation (118% vs 136% and 57% vs 44%, respectively). There was no significant correlation between percentage increase in zinc levels and percentage increase in parameters tested. Height SDS or weight SDS did not improve significantly in 17 patients who continued on zinc supplementation for at least 6 months (6-12 months) (-2.59 vs -2.53 SDS and -1.80 vs -1.67 SDS, respectively). Zinc supplementation increased basal IGF-I, IGFBP-3, alkaline phosphatase and osteocalcin without changing GH response to clonidine. Zinc supplementation did not affect sensitivity to exogenous GH as tested by IGF-I and IGFBP-3 generation test. These results suggest a direct stimulatory effect of zinc on serum IGF-IGFBP-3, alkaline phosphatase and osteocalcin. Despite improvements in the above parameters, zinc supplementation to children with idiopathic short stature with normal serum zinc levels did not significantly change height or weight SDS during 6-12 months follow-up.

Linear growth and zinc supplementation in children with short stature

Physical growth retardation is an early and prominent feature of zinc deficiency, but the effect of zinc supplementation in children is still not completely clear. This study investigated the impact of zinc supplementation on linear growth, growth velocity, IGF-I levels, and skeletal maturation of short children during and after mineral supplementation. The study was designed as a double-blind, randomized, controlled trial of zinc supplementation during a 6-month period, with a subsequent 6-month follow-up. Anthropometric data were collected at 0, 6, and 12 months. Measurements included plasma Zn, IGF-I, height, weight, triceps skinfold thickness, and body mass index. Eighteen healthy pre-pubertal short children (z-score -2.0) 7 to 10 years old with normal GH and IGF-I levels were randomized to two groups, one with zinc supplementation (5 mg/kg/d of ZnSO4) and the other with placebo. In the first 6 months, only height velocity increased significantly, 5.99+/-0.80 cm/yr vs 5.05+/-0.85 cm/yr (p=0.03). After 12 months, height velocity returned to the initial values, 3.92+/-0.59 cm/yr vs 4.19+/-1.08 cm/yr (p=0.29). This study indicates that zinc supplementation increased growth velocity, but these effects did not persist after supplementation was discontinued.