Increased diarrhoeal and respiratory morbidity in association with zinc deficiency--a preliminary report

Zinc supplementation and immune factors in adults: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

This systematic review and meta-analysis aimed to investigate the effect of zinc supplementation on immune factors in randomized controlled trials.

METHODS

A comprehensive search was done in PubMed, Scopus, Web of Science, Embase, and Cochrane databases up to December 2020. We used standard and weighted mean differences and 95% confidence intervals for net changes in selected parameters of immune responses. Subgroup analysis was used to find heterogeneity.

RESULT

Overall, 35 RCTs comprising 1995 participants were eligible for this meta-analysis. There was a significant reduction of circulating CRP (WMD: -32.4; 95% CI: -44.45 to -19.62, p < 0.001), hs-CRP (WMD: -0.95; 95% CI: -1.01 to -0.89, p < 0.001), Neutrophil levels (SMD: -0.46; 95% CI: -0.90 to -0.01, p = 0.043), following zinc supplementation. CD4 level also increased significantly, (WMD: 1.79; 95% CI: 0.57 to 3, p = 0.004). Zinc supplementation had no significant effect on WBC (SMD: -0.66; 95% CI: -1.67 to 0.36, p = 0.204), lymphocyte (WMD: 1.86; 95% CI: -0.86 to 4.58, p = 0.181), monocyte levels (SMD: -0.16; 95% CI: -0.07 to 0.39, p = 0.167), CD3 (SMD: 0.37; 95% CI: -0.49 to 1.22, p = 0.399).

CONCLUSION

Zinc supplementation decreased the CRP, hs-CRP and TNF-α, IL-6, neutrophil and increased CD3 and CD4 level significantly.

Prevalence of Zinc Deficiency and the Effect of Zinc Supplementation on the Prevention of Acute Respiratory Infections

OBJECTIVE

Acute lower respiratory infections are an important cause of morbidity and mortality in developing countries. Recent randomized trials of zinc supplementation for the prevention of acute lower respiratory tract infections have revealed discrepant findings. The main aim of this study was to evaluate the prevalence of zinc deficiency and the effect of zinc supplementation on respiratory infections.

MATERIAL AND METHODS

A single center, prospective open-label interventional single-arm pre-post study of the effect of oral zinc supplementation in zinc deficient children aged 6 months to 5 years was done. A total of 465 healthy children of age 6 months to 5 years were enrolled in the study for estimation of the prevalence of zinc deficiency. Children having zinc deficiency were recruited to study the efficacy and safety of oral administration of 20 mg zinc for two weeks during a 6-month follow-up period.

RESULTS

There were statistically significant differences between the zinc deficient and non-deficient groups according to modified Kuppuswamy categorization of family status and exclusive breast feeding. There was significant difference in the mid arm circumference between the zinc deficient and non-deficient groups (p<0.001). There was significant difference (p<0.001) in the number of episodes of acute upper respiratory infections (AURI), mean duration of AURI, and acute lower respiratory infections (ALRI) between the two groups. There was no significant difference in the ALRI episodes between the two groups. After zinc supplementation in zinc deficient children, there was significant decrease in the number of episodes and mean duration of AURI (p<0.001) and ALRI (p<0.001) within six months after supplementation as compared with the preceding six months before supplementation.

CONCLUSION

This study reveals that a short course of zinc supplementation may reduce the burden of AURI/ALRI among the zinc deficient children, but larger studies are needed.

Zinc supplementation for the promotion of growth and prevention of infections in infants less than six months of age

BACKGROUND

Zinc is a vital micronutrient for humans and is essential for protein synthesis, cell growth, and differentiation. Severe zinc deficiency can lead to slower physical, cognitive and sexual growth, cause skin disorders, decrease immunity, increase incidence of acute illnesses in infants and children and contribute to childhood stunting. By estimation, 17.3% of the world population is at risk of inadequate zinc intake. Such nutritional impairment increases the risk of diarrhoea and pneumonia by 20%, as well as leads to a global loss of more than 16 million disability-adjusted life years in children less than five years of age. Not only does zinc deficiency affect lives, it adds to the considerable financial burden on depleted resources in countries that are most affected. By preventing or curing this deficiency, we can improve childhood mortality, morbidity and growth.

OBJECTIVES

To assess the effectiveness of zinc supplementation for the promotion of growth, reduction in mortality, and the prevention of infections in infants less than six months of age.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 4), MEDLINE via PubMed (1966 to 18 May 2018), Embase (1980 to 18 May 2018), and CINAHL (1982 to 18 May 2018). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. An updated search from 1 January 2018 to 29 January 2020 was run in the following databases: CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost.

SELECTION CRITERIA

All randomised controlled (individual and cluster randomised) and quasi-randomised trials of zinc supplementation in healthy, term infants, less than six months of age comparing infant mortality, incidence of diarrhoea or respiratory illnesses, growth and/or serum zinc levels were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors screened search results (title and abstracts) and relevant full texts. Studies fulfilling prespecified inclusion criteria were included with any disagreements resolved by consensus. Extraction and analysis were then conducted. We used the GRADE approach to assess the quality of evidence as indicated by certainty in effect estimates.

MAIN RESULTS

Eight studies (with 85,629 infants) were included and five studies were meta-analysed, out of which four studies compared zinc with placebo, and one compared zinc plus riboflavin versus riboflavin. Certain growth outcomes after six months of intervention (Weight for Age Z-scores (WAZ) (standardised mean difference) (SMD) 0.16, 95% CI 0.03 to 0.29; three studies, n = 955; fixed-effect; heterogeneity Chi² P = 0.96); I² = 0%); change in WAZ (SMD 0.16, 95% CI 0.07 to 0.25; one study, n = 386; fixed-effect); (Weight-for-Length Z-score (WLZ) (SMD 0.15, 95% CI 0.02 to 0.28; three studies, n = 955; fixed-effect; heterogeneity: Chi² P = 0.81); I² = 0%); (change in WLZ (SMD 0.17, 95% CI 0.06 to 0.28; one study, n = 386; fixed-effect)) were positively affected by zinc supplementation compared to placebo. A single study reported no difference in the incidence of diarrhoea and lower respiratory tract infection with zinc supplementation. Zinc had no effect on mortality in children younger than 12 months. When zinc plus riboflavin was compared to riboflavin only, significant improvement was observed in the incidence of wasting at 24 months (risk ratio (RR) 0.59, 95% CI 0.37 to 0.96; one study, n = 296; fixed-effect), but significant worsening of incidence of stunting was present at 21 months (RR 1.53, 95% CI 1.09 to 2.16; one study, n = 298; fixed-effect).

AUTHORS' CONCLUSIONS

There was a significant positive impact of zinc supplementation on WAZ and WLZ after six months of intervention in infants compared to placebo. When a combined supplement of zinc and riboflavin was compared to riboflavin, there was a significant reduction in wasting at 24 months, but stunting at 21 months was negatively affected. Although included trials were of good-to-moderate quality, evidence that could be meta-analysed was based on a few studies which affected the overall quality of results. Regardless, there is a need for strong trials conducted in infants younger than six months before a strong recommendation can be made supporting zinc supplementation in this age group.

How cellular Zn2+ signaling drives physiological functions

Zinc is an essential micronutrient affecting many aspects of human health. Cellular Zn²⁺ homeostasis is critical for cell function and survival. Zn²⁺, acting as a first or second messenger, triggers signaling pathways that mediate the physiological roles of Zn²⁺. Transient changes in Zn²⁺ concentrations within the cell or in the extracellular region occur following its release from Zn²⁺ binding metallothioneins, its transport across membranes by the ZnT or ZIP transporters, or release of vesicular Zn²⁺. These transients activate a distinct Zn²⁺ sensing receptor, ZnR/GPR39, or modulate numerous proteins and signaling pathways. Importantly, Zn²⁺ signaling regulates cellular physiological functions such as: proliferation, differentiation, ion transport and secretion. Indeed, novel therapeutic approaches aimed to maintain Zn²⁺ homeostasis and signaling are evolving. This review focuses on recent findings describing roles of Zn²⁺ and its transporters in regulating physiological or pathological processes.

The efficacy of zinc supplementation on outcome of children with severe pneumonia. A randomized double-blind placebo-controlled clinical trial

OBJECTIVE

To compare the clinical outcome of children having severe pneumonia, with and without zinc supplementation by a randomized double-blind placebo controlled trial.

METHODS

In this study, 128 children (3-60 months old) admitted to the hospital with severe pneumonia were randomly divided into 2 groups (64 in each) that received either zinc sulfate (2 mg/kg/d, maximum 20 mg in 2 divided doses, for 5 days) or a placebo, along with the standard antimicrobial therapy. Primary outcome measurements included the time taken for clinical symptoms of severe pneumonia such as fever and respiratory distress symptoms to resolve, and the secondary outcome included the duration of hospital stay.

RESULTS

The time taken for all the symptoms to resolve in the zinc-supplemented group was significantly lesser then that in the placebo group (42.26 [6.66] vs. 47.52 [7.15] h respectively, p < 0.001). The zinc-treated group had a significantly shorter duration of fever (23.29 [6.67] vs. 26.6 [6.26] h, p = 0.024), respiratory distress (32.87 [7.85] vs. 37.37 [4.43] h, p = 0.001), required a shorter hospital stay (126.74 [12.8] vs. 137.74 [11.52] h, p < 0.001) than did the controls. The zinc supplement was well tolerated by the children.

CONCLUSIONS

The results suggest that adjuvant treatment with zinc accelerates recovery from severe pneumonia in young children and significantly reduces the duration of hospital stay. Further studies are required to develop appropriate recommendations for the use of zinc in the treatment of severe pneumonia in other populations.

Magnitude of zinc deficiency amongst under five children in India

OBJECTIVE

To estimate the prevalence of serum zinc deficiency in children of 6 months to 60 months of age.

METHODS

A community based cross-sectional study was conducted to collect the data to establish the prevalence of zinc deficiency in children in 6-60 months of age in five states namely, Uttar Pradesh(Northern region), Karnataka (Southern region), Orissa (Eastern region), Gujarat (Western region) and Madhya Pradesh (Central region) of the country. In each state, all the districts with ICDS scheme were enlisted and one district was selected with the help of Random number table (RNT). In each district, all the ICDS projects were selected and one ICDS project was selected with help of RNT. In the selected ICDS project, a cluster 5 Anganwadi centres (AWC) were selected. From the selected AWCs, three hundred children in the age group of 6-60 months were selected for the detailed study. A total of 1,655 subjects (836 males and 819 females) were included. The blood samples were collected from each child. The serum zinc estimation was done by atomic absorption spectrophotometer.

RESULTS

The overall prevalence of zinc deficiency in five states was 43.8% . The prevalence of zinc deficiency was highest in Orissa (51.3%), followed by Uttar Pradesh (48.1%), Gujarat (44.2%), Madhya Pradesh (38.9%) and Karnataka (36.2%).

CONCLUSIONS

The present study revealed a high prevalence of zinc deficiency in children belonging to Low Socio-economic Index (LSI) in India.

Zinc supplementation restores PU.1 and Nrf2 nuclear binding in alveolar macrophages and improves redox balance and bacterial clearance in the lungs of alcohol-fed rats

BACKGROUND

Chronic alcohol abuse causes oxidative stress, impairs alveolar macrophage immune function, and increases the risk of pneumonia and acute lung injury. Recently we determined that chronic alcohol ingestion in rats decreases zinc levels and macrophage function in the alveolar space; provocative findings in that zinc is essential for normal immune and antioxidant defenses. Alveolar macrophage immune function depends on stimulation by granulocyte/monocyte colony-stimulating factor, which signals via the transcription factor PU.1. In parallel, the antioxidant response element signals via the transcription factor Nrf2. However, the role of zinc bioavailability on these signaling pathways within the alveolar space is unknown.

METHODS

To determine the efficacy of dietary zinc supplementation on lung bacterial clearance and oxidative stress, we tested 3 different groups of rats: control-fed, alcohol-fed, and alcohol-fed with zinc supplementation. Rats were then inoculated with intratracheal Klebsiella pneumoniae, and lung bacterial clearance was determined 24 hours later. Isolated alveolar macrophages were isolated from uninfected animals and evaluated for oxidative stress and signaling through PU.1 and Nrf2.

RESULTS

Alcohol-fed rats had a 5-fold decrease in lung bacterial clearance compared to control-fed rats. Dietary zinc supplementation of alcohol-fed rats normalized bacterial clearance and mitigated oxidative stress in the alveolar space, as reflected by the relative balance of the thiol redox pair cysteine and cystine, and increased nuclear binding of both PU.1 and Nrf2 in alveolar macrophages from alcohol-fed rats.

CONCLUSIONS

Dietary zinc supplementation prevents alcohol-induced alveolar macrophage immune dysfunction and oxidative stress in a relevant experimental model, suggesting that such a strategy could decrease the risk of pneumonia and lung injury in individuals with alcohol use disorders.

Zinc status in HIV infected Ugandan children aged 1-5 years: a cross sectional baseline survey

BACKGROUND

Low concentrations of serum zinc have been reported in HIV infected adults and are associated with disease progression and an increased risk of death. Few studies have been conducted in HIV infected children in Africa. We determined serum zinc levels and factors associated with zinc deficiency in HIV infected Ugandan children.

METHODS

We measured the baseline zinc status of 247 children aged 1-5 years enrolled in a randomised trial for multiple micronutrient supplementation at paediatric HIV clinics in Uganda (http://ClinicalTrials.gov NCT00122941). Zinc status was determined using inductively coupled atomic emission spectrophotometry (ICP-AES). Clinical and laboratory characteristics were compared among zinc deficient (zinc < 10.0 μmol/L) and non deficient children. Logistic regression was used to determine predictors of low serum zinc.

RESULTS

Of the 247 children, 134 (54.3%) had low serum zinc (< 10.0 μmol/L). Of the 44 children on highly active antiretroviral therapy (HAART), 13 (29.5%) had low zinc compared to 121/203 (59.6%) who were not on HAART. Overall, independent predictors of low zinc were fever (OR 2.2; 95%CI 1.1-4.6) and not taking HAART (OR 3.7; 95%CI 1.8-7.6).

CONCLUSION

Almost two thirds of HAART naïve and a third of HAART treated HIV infected children were zinc deficient. Increased access to HAART among HIV infected children living in Uganda might reduce the prevalence of zinc deficiency.

Essential role of vitamin C and zinc in child immunity and health

With the progressive elimination of dietary protein-energy deficits, deficiencies of micronutrients are emerging as the limiting factors in ensuring children's optimal health. Data from several countries in Asia and Latin America indicate that deficiencies of vitamin C and zinc continue to be at alarming levels. This article reviews the roles of vitamin C and zinc in supporting children's growth and development, with a particular focus on the complementary roles they play in supporting immune functions and combating infections. The contemporary relevance of vitamin C and zinc deficiency in the Asian and Latin American regions, both undergoing a rapid nutritional transition, are also discussed. Overall, there is increasing evidence that deficiency of vitamin C and zinc adversely affects the physical and mental growth of children and can impair their immune defences. Nutrition should be the main vehicle for providing these essential nutrients; however, supplementation can represent a valid support method, especially in developing regions.

Symptomatic acquired zinc deficiency in at-risk premature infants: high dose preventive supplementation is necessary

Zinc is a cofactor for several enzymes involved in many metabolisms. Zinc deficiency induces various disorders such as acrodermatitis enteropathica, either inherited or acquired. We report three cases of premature infants (24-31 wks gestational age) with low birthweight (650 to 940 g) and enteropathy, two of whom presented with necrotizing enterocolitis. All infants were fed by total parenteral nutrition. At a chronological age ranging from 73 to 80 days, all infants developed a periorificial dermatitis. Before the onset of the first signs, they had received zinc supplementation ranging from 146% to 195% of the recommended dose (400 microg/kg/day). Increased zinc supplementation over a course of 6-18 days induced a complete resolution of symptoms in all cases. No abnormality in the neurologic examination and no recurrence were observed at the end of the zinc treatment. Low birthweight premature infants with enteropathy on total parenteral nutrition are at risk of developing zinc deficiency. The usual recommended zinc supplementation is probably insufficient for those infants. A delay in the diagnosis of zinc deficiency may lead to severe complications.

Effect of zinc supplementation on morbidity and growth in hospital-born, low-birth-weight infants

BACKGROUND

Low-birth-weight infants may have impaired zinc status, but little is known about the effect of zinc supplementation.

OBJECTIVE

The objective was to investigate the effect of daily zinc supplementation on morbidity and anthropometric status in hospital-born, low-birth-weight infants.

DESIGN

In a double-blind, randomized, placebo-controlled trial, 2052 hospital-born term infants with a birth weight < or =2500 g were randomly assigned to receive zinc or placebo. The zinc group received elemental zinc: 5 mg/d for those infants between ages 2 wk and 6 mo and 10 mg/d for those infants aged >6 mo. All-cause hospitalizations, prevalence of diarrhea, acute lower respiratory tract infections, visits to health care providers, weights, and lengths were ascertained at 3, 6, 9, and 12 mo of age.

RESULTS

The supplement was consumed for >85% of the follow-up period. Mean plasma zinc at 12 mo of age was higher in the zinc group (100.2 microg/dL) than in the control group (73.3 microg/dL) (difference in means: 26.9; 95% CI: 19.6, 34.2). The 24-h and 7-d prevalence of diarrhea and acute lower respiratory tract infections was similar at 3, 6, 9, and 12 mo. Care-seeking for illness was significantly lower in the zinc group (difference in proportions: -5.7; 95% CI: -9.9, -1.4; P < 0.05) at 9 mo. The numbers of hospitalizations, weights, and lengths were all similar at all 4 assessments.

CONCLUSION

Hospital-born, term, low-birth-weight infants do not seem to benefit substantially from zinc supplementation that meets the Recommended Dietary Allowance for zinc in terms of morbidity or physical growth during infancy in this setting. This trial was registered at www.clinicaltrials.gov as NCT00272142.

Adding zinc to supplemental iron and folic acid does not affect mortality and severe morbidity in young children

Studies have found a substantial reduction in diarrhea and respiratory morbidity in young children receiving zinc supplementation. The impact of daily zinc supplementation administered with iron plus folic acid (IFA) in young children on all-cause hospitalizations and mortality in comparison with IFA alone was evaluated. In a double blind cluster-randomized controlled trial, 94,359 subjects aged 1-23 mo were administered a daily dose of zinc plus IFA or IFA alone for a duration of 12 mo after enrollment. The intervention group tablet contained 10 mg of elemental zinc, 12.5 mg of iron, and 50 microg of folic acid. The control group tablets were similar except that they contained a placebo for zinc. Infants aged <6 mo were administered half a tablet, and those older received 1 tablet dissolved in breast milk or water. Hospitalizations were captured by trained study physicians through the surveillance of 8 hospitals. Deaths and hospitalizations were ascertained through visits to households by study supervisors once every 2 mo. The overall death rates did not differ significantly between the 2 groups when adjusted for cluster randomization (hazard ratio = 1.02, 95% CI 0.87, 1.19). Zinc and IFA supplementation compared with IFA alone did not affect adjusted hospitalization rates (overall rate ratio = 1.08, 95% CI 0.98, 1.19; diarrhea-specific rate ratio = 1.15, 95% CI 0.99, 1.34; or pneumonia-specific rate ratio = 1.09, 95% CI 0.94, 1.25). The lack of impact of zinc on mortality and hospitalization rates in this study may have been due to the use of lower daily zinc dosing than used in some of the morbidity prevention trials or from an interaction between zinc and iron, where the addition of iron may have adversely affected potential effects of zinc on immune function and morbidity. Future research should address iron and zinc interaction effects on important functional outcomes.

Impact of zinc supplementation on mental and psychomotor scores of children aged 12 to 18 months: a randomized, double-blind trial

OBJECTIVE

To evaluate the effect of zinc supplementation on mental and psychomotor scores in children aged 12 to 18 months.

STUDY DESIGN

In this double-blind, randomized, placebo-controlled trial, children aged 6 to 30 months received daily elemental zinc (10 mg for infants and 20 mg for others) or placebo for 4 months. Bayley Scales of Infant Development II were used for development assessment in the 12- to 18-month subgroup at enrollment and the end of the study.

RESULTS

At the end of the study, the adjusted mean mental ( P = .36) and psychomotor ( P = .28) index scores were similar in the intervention and control groups. In a multivariate model, the baseline mental development index score was positively associated with the mother's schooling, the child's height for age, packed cell volumes, hospital birth, and attendance at a day care center, and was negatively associated with the child's age. Breastfeeding, the child's weight for height, and packed cell volumes were positively associated with the baseline psychomotor index score.

CONCLUSION

Zinc supplementation did not affect the mental or psychomotor development index scores in a setting in which zinc deficiency is common.

Effect of zinc supplementation on immune and inflammatory responses in pediatric patients with shigellosis

BACKGROUND

Several studies showed benefits of long-term zinc supplementation on the incidence, severity, and duration of diarrhea and on the incidence of respiratory infections. Prolonged zinc supplementation also improves cell-mediated immunity in severely malnourished children.

OBJECTIVE

We studied the effect of short-term zinc supplementation on intrinsic and specific immune and inflammatory responses in moderately malnourished children with acute shigellosis.

DESIGN

A randomized, double-blind, placebo-controlled trial was conducted in Shigella-infected children aged 12-59 mo. Elemental zinc (20 mg) and a multivitamin containing vitamins A and D, thiamine, riboflavin, nicotinamide, and calcium at twice the recommended dietary allowance were given daily for 2 wk to the zinc group (n = 28), whereas the multivitamin alone was given to the control group (n = 28). Standard antibiotic therapy was given to all patients.

RESULTS

Serum zinc concentrations increased in both groups during convalescence; however, zinc supplementation showed a significant effect. The lymphocyte proliferation response in the zinc group increased relative to that in the control group (P = 0.002), but no significant effects were seen on concentrations of cytokines (interleukin 2 and interferon gamma) released from mitogen-stimulated mononuclear cells or on concentrations of cytokines (interleukin 2, interferon gamma, and interleukin 1beta) in feces. Among the antigen [lipopolysaccharide and invasion plasmid-encoded antigen (Ipa)]-specific antibodies, plasma Ipa-specific immunoglobulin G responses at day 30 were significantly higher in the zinc group than in the control group. However, the 2 groups did not differ significantly in the other antigen-specific responses in plasma and stool.

CONCLUSION

A 14-d course of zinc supplementation during acute shigellosis increases the lymphocyte proliferation response and the Ipa-specific immunoglobulin G response.

Zinc with oral rehydration therapy reduces stool output and duration of diarrhea in hospitalized children: a randomized controlled trial

OBJECTIVES

The authors evaluated the effect of zinc treatment as an adjunct to oral rehydration therapy on stool output and diarrheal duration in children with acute noncholera diarrhea with dehydration.

METHODS

This double-blind, randomized, controlled trial was conducted at two urban hospitals in New Delhi. A total of 287 dehydrated male patients, ages 3 to 36 months, with diarrhea for <or= 72 hours were enrolled. They were assigned to zinc or placebo by a randomization scheme stratified by age (<or= or >12 months) and weight for height (65%-80% or >80% National Centre for Health Statistics median). Participants in the zinc group received 15 mg (<or=12 months) or 30 mg (>12 months) elemental zinc daily in three divided doses for 14 days. The main outcome measures were stool output and diarrheal duration.

RESULTS

Zinc treatment reduced total stool output (ratio of geometric means, 0.69; 95% confidence interval [CI]: 0.48, 0.99) and stool output per day of diarrhea (ratio of geometric means, 0.76; 95% CI: 0.59, 0.98). The risk of continued diarrhea was lower (relative hazards, 0.76; 95% CI: 0.59, 0.97) and the proportion of diarrheal episodes lasting >or= 5 days (odds ratio, 0.49; 95% CI: 0.25, 0.97) or >or= 7 days was less (odds ratio, 0.09; 95% CI: 0.01, 0.73) in the zinc group.

CONCLUSIONS

This study demonstrates a beneficial effect of zinc administered during acute diarrhea on stool output, diarrheal duration, and proportion of episodes lasting more than 7 days. The effects are large enough to merit routine use of zinc during acute diarrhea in developing countries.

Zinc supplementation in Brazilian children with acute diarrhoea

Although oral rehydration therapy greatly reduces mortality from diarrhoeal diseases, it has little effect on stool frequency. However, there is mounting evidence that zinc is an effective adjunct to the treatment of diarrhoea, although few studies have examined its efficacy in Latin America. This study assessed the efficacy of zinc supplementation in children with acute diarrhoea in Brazil. The study was a double-blind, placebo-controlled, randomised, clinical trial in children <5 years of age attending emergency services in Sergipe, Brazil. Subjects received zinc or vitamin C as placebo. There was a marked reduction in the duration of the diarrhoea (1.1 vs 2.6 days) and of watery stools in the zinc-supplemented group. The efficacy of zinc was independent of the presence of viral enteropathogens in the stools. It is concluded that, similar to studies in India and Bangladesh, zinc could be an important adjunct for treating acute diarrhoea in Brazilian children.

Ethnomedical knowledge of plants used by Kunabi Tribe of Karnataka in India

Therapeutic effects and medicinal efficacy of the wild herbs were identified and administered by the tribal people to cure various ailments. Recently, the practice of herbal medicine has been diminishing, which may lead to the loss of valuable information about healing herbs. The Uttara Kannada District of Karnataka in India is one of the rich biodiversity centers of Western Ghats. Many tribes like Gowlis, Siddis, Halakki Okkaligas and Kunabis inhabit the semi-evergreen forests of the District. The mixed marathi speaking Kunabis have migrated from Goa and settled here a long time back and are even today without modern facilities. Thus, in the way of revitalization of traditional herbal medicines, it is an effort to record the valuable ethnomedical knowledge of the tribe Kunabis of Uttara Kannada District in Karnataka. A total of 45 species of plants used by Kunabi community people are described here based on an ethnomedical field survey. These plants belong to 26 families and are used to treat a wide range of discomforts like fever, cough, skin diseases, rheumatism, snakebite, jaundice, dysentery, etc.

Effect of routine zinc supplementation on pneumonia in children aged 6 months to 3 years: randomised controlled trial in an urban slum

OBJECTIVES

To evaluate the effect of daily zinc supplementation in children on the incidence of acute lower respiratory tract infections and pneumonia.

DESIGN

Double masked, randomised placebo controlled trial.

SETTING

A slum community in New Delhi, India.

PARTICIPANTS

2482 children aged 6 to 30 months.

INTERVENTIONS

Daily elemental zinc, 10 mg to infants and 20 mg to older children or placebo for four months. Both groups received single massive dose of vitamin A (100 000 IU for infants and 200 000 IU for older children) at enrollment.

MAIN OUTCOME MEASURES

All households were visited weekly. Any children with cough and lower chest indrawing or respiratory rate 5 breaths per minute less than the World Health Organization criteria for fast breathing were brought to study physicians.

RESULTS

At four months the mean plasma zinc concentration was higher in the zinc group (19.8 (SD 10.1) v 9.3 (2.1) micromol/l, P<0.001). The proportion of children who had acute lower respiratory tract infection during follow up was no different in the two groups (absolute risk reduction -0.2%, 95% confidence interval -3.9% to 3.6%). Zinc supplementation resulted in a lower incidence of pneumonia than placebo (absolute risk reduction 2.5%, 95% confidence interval 0.4% to 4.6%). After correction for multiple episodes in the same child by generalised estimating equations analysis the odds ratio was 0.74, 95% confidence interval 0.56 to 0.99.

CONCLUSIONS

Zinc supplementation substantially reduced the incidence of pneumonia in children who had received vitamin A.

Substantial reduction in severe diarrheal morbidity by daily zinc supplementation in young north Indian children

OBJECTIVE

To evaluate the impact of 4 months of daily zinc supplementation on the incidence of severe and recurrent diarrhea in children 6 to 30 months of age.

METHODS

A double-blind, randomized, placebo-controlled trial was conducted on children who were identified by a door-to-door survey to be aged 6 to 30 months and residing in the urban slum of Dakshinpuri, New Delhi. They were randomized to receive daily zinc gluconate (elemental zinc 10 mg to infants and 20 mg to older children) or placebo. A field attendant administered the syrup daily at home for 4 months except on Sundays, when the mother did so. One bottle that contained 250 mL was kept in the child's home and replaced monthly. Field workers visited households every seventh day during the 4-month follow-up period. At each visit, information was obtained for the previous 7 days on history of fever, number and consistency of stools, and presence of cough. When the child was ill, illness characteristics and treatment seeking outside the home were determined. If the child had diarrhea or vomiting, then dehydration was assessed. At household visits, 2 packets of oral rehydration salts were given when a child had diarrhea. Children who visited the study clinic spontaneously for illness or were referred by the field workers were treated according to the standard national program guidelines. Antibiotics were advised only for diarrhea with bloody stools or for associated illnesses. For using generalized estimating equations for longitudinal analysis of a recurring event such as diarrhea, the follow-up data for each child was divided into 17 child-periods of 7 days each and presence or absence of an incident episode of diarrhea or severe diarrhea within each 7-day period was coded. This method of analysis does not assume independence of events and therefore prevents underestimation of variance that results because of correlation of morbidity within the same child. A logistic generalized estimating equations model with exchangeable correlation covariance-variance matrix was then used to estimate the effect size.

RESULTS

Zinc or placebo doses were administered on 88.8% and 91.2%, respectively, of study days during the 4 months of follow-up. There was a small but significant increase in the average number of days with vomiting in the zinc group (4.3 [standard deviation (SD): 5.8] vs 2.6 [SD 3.9] days; difference in means: 1.7 [95% confidence interval (CI): 1.3-2.1] days). At the baseline, mean plasma zinc was 62.0 microg/dL (SD: 14.3 microg/dL) in the zinc and 62.0 microg/dL (SD: 11.2 microg/dL) in the placebo group; 45.8% and 42%, respectively, had low plasma zinc levels below 60 microg/dL. At the end of the study, plasma zinc levels were substantially higher in the zinc group (ratio of geometric means: 1.94 [95% CI: 1.86-2.03]) and the proportion with low plasma zinc was lower (difference in proportions: -46.7% [95% CI: -41.8% to -51.4%]). The incidence of diarrhea during follow-up was lower in the zinc-supplemented as compared with the placebo group (odds ratio [OR]: 0.88; 95% CI: 0.82-0.95). The beneficial impact of zinc was greater on the incidence of diarrhea with progressively increasing duration: episodes of diarrhea that lasted 1 to 6 days (OR: 0.92; 95% CI: 0.85-1.00), 7 to 13 days (OR: 0.79; 95% CI: 0.65-0.95), and > or =14 days (OR: 0.69; 95% CI: 0.48-0.98). The impact was also greater on the incidence of episodes with progressively higher stool frequency: 3 to 5 stools per day (OR: 0.90; 95% CI: 0.83-0.98), 6 to 9 stools per day (OR: 0.87; 95% CI: 0.77-0.98), and > or =10 per day (OR: 0.77; 95% CI: 0.63-0.94). In the zinc group, significantly more children experienced no diarrheal episode during the study period (risk ratio [RR]: 1.22; 95% CI: 1.02-1.44). Furthermore, substantially fewer children (RR: 0.51; 95% CI: 0.36-0.73) experienced recurrent diarrhea, defined as >6 diarrheal episodes in the follow-up period as compared with children in the placebo group. The number of children who were hospitalized for any cause tended to be lower in the zinc group, but the difference was not statistically significant (1.79% vs 2.43%; RR: 0.74; 95% CI: 0.43-1.27). The baseline mean plasma copper (microg/dL) was similar in the 2 groups (difference in means: 1.6; 95% CI: -2.9 to 6.1). The end study plasma copper levels were significantly lower in the zinc group (difference in means: -15.5; 95% CI: -19.9 to - 11.1).

CONCLUSIONS

Zinc supplementation substantially reduced the incidence of severe and prolonged diarrhea, the 2 important determinants of diarrhea-related mortality and malnutrition. This intervention also substantially reduced the proportion of children who experienced recurrent diarrhea. Prompt measures to improve zinc status of deficient populations are warranted. The potential approaches to achieve this goal include food fortification, dietary diversification, cultivation of plants that are zinc dense or have a decreased concentration of zinc absorption inhibitors, and supplementation of selected groups of children. Future studies should assess the impact of increased zinc intakes on childhood mortality in developing countries. For facilitating intervention, there is a need to obtain reliable estimates of zinc deficiency, particularly in developing countries. The functional consequences of the effect of various doses of zinc on plasma copper levels merits additional study.

Immunobiology of mild micronutrient deficiencies

Nutrition is a critical determinant of the outcome of host microbe interactions through a modulation of the immune response. Besides macronutrient malnutrition, deficiencies of several macronutrients also influence immune homeostasis and thus affect infection-related morbidity and mortality. Deficiencies of micronutrients like vitamin A, iron and zinc are widely prevalent among populations living in developing countries. Besides their severe deficiencies, subclinical deficiencies are known to impair biological functions in the host, immune function being one of them. The effects of these micronutrients on various immune mechanisms are briefly reviewed in this article.