Brazilian studies on zinc deficiency and supplementation: emphasis on children

a literature review based on bibliographic research was carried out in SciELO, LILACS and MEDLINE/PUBMED databases. A total of 133 studies on zinc deficiency and 116 on the effects of supplementation were identified. Thirty-two articles, 16 of which were observational and 16 interventional, were analyzed.

Results:

the studies focused mainly on children (75.0% of the observational and 81.25% of the experimental studies). Biochemical deficiency of zinc in children presented great variability, from 0.0% to 74.3%, with expressive prevalence in most studies. Dietary inadequacy among children presented variability from 16.6% to 46.0%. Five from seven studies showed a positive effect of zinc supplementation on micronutrient nutritional status.

Conclusions:

there is evidence of zinc deficiency in children as a public health problem, preventable through micronutrient supplementation.

Key words
Zinc; Nutritional status; Child; Brazil

Author, year	Target group	Diagnostic methods	Main results (prevalences and associations)
Jardim-Botelho et al.,¹⁵15 Jardim-Botelho A, Gurgel RQ, Henriques GS, Santos CB, Jordão AA, Faro FN, Silveira Souto FM, Rodrigues Santos AP, Eduardo Cuevas L. Micronutrient deficiencies in normal and overweight infants in a low socio-economic population in north-east Brazil. Paediatr Int Child Health. 2015, 8: 1-5. 2015	153 children, 2 to 11 months old, born at term, living in areas of social vulnerability of Laranjeiras, SE	Biochemical evaluation: plasma zinc, erythrocyte zinc	-Plasma zinc deficiency: 58% -Erythrocyte zinc deficiency: 67% -Significantly lower plasma zinc concentrations in normal weight children -There was no statistical difference between erythrocyte zinc concentrations and E/I index
Garcia et al.,¹⁶16 Garcia MT, Granado FS, Cardoso MA. Alimentação complementar e estado nutricional de crianças menores de dois anos atendidas no Programa Saúde da Família em Acrelândia, Acre, Amazônia Ocidental Brasileira. Cad Saúde Pública. 2011; 27 (2): 305-16. 2011	164 children, aged 6 to 24 months, living in the urban area of Acroelândia, AC	Dietary assessment: food consumption by food history	-Inadequate dietary intake of zinc: 46%
Figueroa Pedraza et al.,¹⁷17 Figueroa Pedraza D, Rocha ACD, Queiroz EO, Sousa CPC. Estado nutricional relativo ao zinco de crianças que frequentam creches do estado da Paraíba. Rev Nutr. 2011; 24 (4): 539-52. 2011	235 children, aged 6 to 72 months, assisted in day care centers in the State of Paraíba	-Biochemical evaluation: serum zinc -Dietary assessment: food consumption through 24-hour recall	-Zinc deficiency: 16.2% -Inadequate dietary intake of zinc: 16.6% -Mean zinc concentrations significantly lower in children of low weight mothers than in children of normal weight mothers -There was no statistical difference between serum zinc concentrations according to dietary zinc adequacy, height-for-age (H/A) index, and variables related to children's biological characteristics, infant feeding, family history and socioeconomic conditions
Beinner ¹⁸18 Beinner MA, Menezes MABC, Silva JBB, Amorim FR; Jansen AK; Lamounier JA. Zinco plasmático e zinco capilar, antropometria e consumo alimentar de crianças em uma região rural do Brasil. Rev Nutr. 2010; 23 (1): 75-83., 2010	176 children, aged 6 to 24 months, living in a rural area of Diamantina, MG	-Biochemical evaluation: plasma zinc, zinc in hair -Dietary assessment: food consumption through 24-hour recall	-Plasma zinc deficiency: 11.2% -Zinc deficiency in hair: 16.8% -Inadequate dietary intake of zinc: 30.6% -There was no statistical difference between zinc deficiencies in plasma and hair, according to sex -Absence of correlation between plasma zinc concentrations, zinc content in hair, anthropometric indices (W/A, H/A, W/H) and dietary zinc intake
Custodio et al.,¹⁹19 Custodio V, Daneluzzi JC, Custodio RJ, Del Ciampo LA, Ferraz IS, Martinelli Júnior CE, Ricco RG, Cupo P, Hering SE, Meirelles MS, Vannucchi H. Vitamin A deficiency among Brazilian school-aged children in a healthy childservice. Eur J Clin Nutr. 2009; 63 (4): 485-90. 2009	103 children, 5.5 to 11 months old, assisted at a health unit in Ribeirão Preto, SP	Biochemical evaluation: serum zinc	-Zinc Deficiency: 0% -Lack of statistical association between serum zinc concentrations and vitamin A deficiency
Costa et al.,²⁰20 Costa GA, Marreiro DN, Eulálio JM, Moita Neto J, Amorim AC, Nogueira AM, et al. Erythrocytary zinc and the infant growth profile in northeast Brazil. Bio Trace Elem Res. 2008; 126 (Supl 1): 15-20. 2008	239 children, aged 3 to 6 years, assisted in day care centers in Teresina, PI	Biochemical evaluation: erythrocyte zinc	-Zinc Deficiency: 74.3% -Absence of statistical association between serum zinc concentrations and anthropometric indices (W/A, H/A, W/H)
Borges et al.,²¹21 Borges CVD, Veiga APB, Barrosa GS, Jesus EFO, Serpa RFB, Moreira S, Salles-Costa R. Associação entre concentrações séricas de minerais, índices antropométricos e ocorrência de diarréia entre crianças de baixa renda da região metropolitana do Rio de Janeiro. Rev Nutr. 2007; 20 (2): 159-69. 2007	104 children, aged 1 to 5 years, living in the urban area of Duque de Caxias, RJ	Biochemical evaluation: serum zinc	-Zinc Deficiency: 7.5% -Assessment of statistical association between serum zinc concentrations and anthropometric indices (W/A, H/A) -Mean zinc concentrations significantly lower in children with diarrhea than those without reported diarrhea
Ferraz et al.,²²22 Ferraz IS, Daneluzzi JC, Vannucchi H, Jordão Jr AA, Ricco RG, Del Ciampo LA, Martinelli CE Jr, Engelberg AA, Bonilha LR, Custódio VI. Zinc serum levels and their association with vitamin A deficiency in preschool children. J Pediatr (Rio J). 2007; 83 (6): 512-7. 2007	182 children, aged ≥ 2 years and < 6 years, assisted at the Social Medical Center and Community of Vila Lobato, Ribeirão Preto, SP	Biochemical evaluation: serum zinc	-Zinc Deficiency: 0.5% -Lack of correlation between serum concentrations of zinc and retinol -Lack of correlation between serum zinc concentrations in males and females -Children aged ≥ 48 to <60 months had lower serum zinc concentrations than children of other ages -Concentrations of serum zinc did not change due to diarrhea and/or fever episodes
Santos et al.,²³23 Santos EB; Amancio OMS; Oliva CAG. Nutritional status, iron, copper, and zinc in school children of shantytwons of Sao Paulo. Rev Assoc Med Bras. 2007; 53 (4): 323-8. 2007	86 schoolchildren, aged 7 to 15 years, living in two favelas (Rocinha and Beira Rio) in the city of São Paulo, SP	Biochemical evaluation: serum zinc	-Zinc deficiency: 8.14% -Mean concentrations of zinc without significant difference according between sexs and non-correlated to presence of anemia
Maia et al.,²⁴24 Maia PA, Figueiredo RC, Anastácio AS, Silveira CLP, Donangelo CM. Zinc and copper metabolism in pregnancy and lactation of adolescent women. Nutrition. 2007; 23 (3): 248-53. 2007^* * Results on the prevalence of zinc deficiency with the use of biochemical indicators and/or prevalence of dietary inadequacy of dietary zinc not available in the articles; H/A = Height-for-age; W/H = Weight-for-height; W/A = Weight-for-age.	73 female adolescents, from 14 to 18 years of age, Health centers of Rio de Janeiro, RJ	-Biochemical evaluation: plasma zinc, erythrocyte zinc, alkaline phosphatase, metallothionein, superoxide dismutase -Dietary assessment: food consumption through 24-hour recall	-Inadequate dietary intake of zinc (pregnant adolescents): 67% -Inadequate dietary intake of zinc (non-pregnant and non-lactating adolescents): 78% -Inadequate dietary intake of zinc (lactating adolescents): 77% -Concentrations of plasma zinc in pregnant adolescents were lower than that of non-pregnant and non-lactating adolescents, and of lactating adolescents -Concentration of erythrocyte zinc did not differ between pregnant adolescents, non-pregnant and non-lactating adolescents, and lactating adolescents -Significant correlation between erythrocyte zinc and metallothionein levels in non-pregnant and non-lactating adolescents and lactating adolescents, a fact not observed in pregnant adolescents -Significant correlation between alkaline phosphatase and plasma zinc concentrations between metallothionein and plasma zinc concentrations and between concentrations osuperoxide dismutase and erythrocyte zinc in non-pregnant and non-lactating adolescents, a fact not observed in pregnant adolescents and lactating adolescents
Tremeschin et al.,²⁵25 Tremeschin MH, Cervi MC, Camelo Júnior JD, Negrini BV, Martinez FE, Motta F, Meirelles MS, Vanucchhi H, Monteiro JP. Niacin nutritional status in HIV type 1-positive children: preliminary data. J Pediatr Gastroenterol Nutr. 2007; 44(5): 629-33. 2007^* * Results on the prevalence of zinc deficiency with the use of biochemical indicators and/or prevalence of dietary inadequacy of dietary zinc not available in the articles; H/A = Height-for-age; W/H = Weight-for-height; W/A = Weight-for-age.	40 preschool children, distributed in three groups according to AIDS-related characteristics, living in the city of Ribeirão Preto, SP	Dietary assessment: food consumption by frequency of consumption	-Dietary zinc intake without statistical difference between HIV-positive children, HIV-negative children born to infected mothers and HIV-negative children
Morimoto et al.,²⁶26 Morimoto JM, Marchioni DML, Fisberg RM. Using dietary reference intake-based methods to estimate prevalence of inadequate nutrient intake among female students in Brazil. J Am Diet Assoc. 2006; 106 (5): 733-6. 2006	119 students, aged 19 to 30, from a public university in the State of São Paulo	-Dietary assessment: food consumption per non-consecutive 3-day record	-Inadequate dietary zinc intake: 47%
Cesar et al.,²⁷27 Cesar TB, Wada SR, Borges RG. Zinco plasmático e estado nutricional em idosos. Rev Nutr. 2005; 18 (3): 357-65. 2005^* * Results on the prevalence of zinc deficiency with the use of biochemical indicators and/or prevalence of dietary inadequacy of dietary zinc not available in the articles; H/A = Height-for-age; W/H = Weight-for-height; W/A = Weight-for-age.	80 elderly assisted at the Araraquara Rehabilitation Center, SP	-Biochemical evaluation: plasma zinc -Dietary assessment: food consumption through 24-hour recall and frequency of consumption	-Mean concentrations of plasma zinc below the references for age in both men and women -Mean dietary zinc intake according to normality patterns in both men and women -Lack of correlation between dietary intake of zinc and plasma zinc -Significant correlation between dietary intake of zinc and energy and protein intake in women, a fact also observed in men for protein intake -Meats provided 68% of total zinc in the case of women and 78% in the case of men
Weyenbergh et al.,²⁸28 Weyenbergh JV, Santana G, D'Oliveira Júnior A, Santos Júnior AF, Costa CH, Carvalho EM, Barral AMP, Barral Neto M. Zinc/copper imbalance reflects immune dysfunction in human leishmaniasis: an ex vivo and in vitro study. BMC Infect Dis. 2004; 4: 50-9. 2004	31 individuals with leishmaniasis and 25 controls of endemic and non-endemic areas, living in the rural district of Corte da Pedra, Bahia	-Biochemical evaluation: plasma zinc	-Zinc Deficiency (total): 25.8% -Zinc Deficiency (with visceral leishmaniasis): 70% -Zinc deficiency (carriers of mucosal leishmaniasis): 14.2% -Zinc Deficiency (carriers of localized cutaneous leishmaniasis): 0% -Zinc Deficiency (Controls): 0% -Lower plasma levels of zinc in leishmaniasis patients compared to controls
Marinho e Roncada,²⁹29 Marinho HA, Roncada MJ. Ingestão e hábitos alimentares de pré-escolares de três capitais da Amazônia Ocidental Brasileira: um enfoque especial à ingestão de vitamina A. Acta Amaz. 2002; 33 (2): 263-74. 2002	370 children, 3 to 6 years old, living in three capitals of the Western Amazon: Boa Vista (n = 54), Manaus (n = 238) and Porto Velho (n = 78)	Dietary assessment: food consumption through 24-hour recall and frequency of consumption	-Inadequate dietary intake of zinc (total): 27.2% -Inadequate dietary intake of zinc (Boa Vista): 16.3% -Inadequate dietary intake of zinc (Manaus): 30.3% -Inadequate dietary intake of zinc (Porto Velho): 25.5% -The mean daily consumption of zinc in Boa Vista, Manaus and Porto Velho was 8.4 (± 2.0) mg, 6.9 (± 1.7) mg and 7.4 (± 1.8) mg , respectively -16.7%, 19.8% and 18.0% of the children of Boa Vista, Manaus and Porto Velho, respectively, consumed less than 50% of the daily recommendations of zinc
Fávaro et al.,³⁰30 Fávaro RMD, Vannucchi H. Níveis plasmáticos de zinco e antropometria de crianças da periferia de centro urbano no Brasil. Rev Saúde Pública. 1990; 24 (1): 5-10. 1990	126 children, aged 2 to 7 years, living in three peripheral districts of Ribeirão Preto, SP	Biochemical evaluation: plasma zinc	-Zinc Deficiency: 13% -Lack of statistical difference between the prevalence of zinc deficiency in girls (14%) and boys (11.7%) -Absence of statistical association between serum zinc concentrations and anthropometric indices (W/H, tricipital fold, brachial circumference)

Author, year	Target group	Diagnostic methods	Tipe of intervention	Main results (intervention effects)
Lima et al.,³¹31 Lima AA, Kvalsund MP, Souza PP, Figueiredo ÍL, Soares AM, Mota RM, Lima NL, Pinkerton RC, Patrick PP, Guerrant RL, Oriá RB. Zinc, vitamin A, and glutamine supplementation in Brazilian shantytown children at risk for diarrhea results in sex-specific improvements in verbal learning. Clinics (São Paulo). 2013; 68 (3): 351-8. 2013	167 children, aged 3 months to nine years, with short stature, living in favelas in Fortaleza,CE	No evaluation	Supplementation alone or combined with zinc, vitamin A and glutamine	-Significantly higher verbal learning scores in female children supplemented with zinc, vitamin A and glutamine than those supplemented with zinc and vitamin A and those receiving placebo alone
Moura et al.,³²32 Moura JE, Moura ENO, Alves CX, Vale SHL, Dantas MMG, Silva AA, Almeida Md, Leite LD, Brandão-Neto J. Oral Zinc supplementation may improve cognitive function in schoolchildren. Biol Trace Elem Res. 2013; 155: 23-8. 2013	36 children, aged 6 to 9 years, from Natal, RN	Biochemical evaluation: serum zinc	Zinc suplementation	-Significant improvement in Verbal Intelligence Quotient and in Intelligence Quotient Performance after supplementation -Significant increase in serious zinc levels during intravenous administration of zinc and after supplementation -Significant increases in plasma concentrations of GH Growth Hormone during intravenous administration of zinc -Significant increase in plasma concentrations of IGF-1-like Growth Factor and IGFBP3 Insulin-Like Growth Factor Binding Protein 5 after supplementation
Alves et al.,³³33 Alves CX, Vale SHL, Dantas MMG, Maia AA, Franca MC, Marchini JS, Leite LD, Brandao-Neto J. Positive effects of zinc supplementation on growth, GH, IGF1, and IGFBP3 in eutrophic children. J Pediatr Endocr Met. 2012; 25 (9-10): 881-7. 2012	30 children, aged 6 to 9 years, enrolled in schools in the city of Natal, RN	Biochemical evaluation: serum zinc	Supplementation with zinc versus intravenous zinc administration	-Significant increase in weight and consumption of energy, protein, carbohydrate, calcium, iron and zinc after supplementation -Positive correlation between the areas under the curve of Growth Hormone GH and zinc after supplementation
Mitter et al.,³⁴34 Mitter SS, Oriá RB, Kvalsund MP, Pamplona P, Joventino ES, Mota RM, Gonçalves DC, Patrick PD, Guerrant RL, Lima AAM. Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil. Clinics (São Paulo). 2012; 67 (1): 11-8. 2012	213 children, aged 2 months to 9 years, with short height, living in favelas in Fortaleza, CE	No evaluation	Supplementation alone or combined with zinc, vitamin A and glutamine	-Improvements in the lactulose/mannitol ratio in children with apolipoprotein E positive and apolipoprotein E negative genotype after supplementation with vitamin A, zinc and glutamine -No significant differences in the anthropometric indices (W/A, H/A, W/H) between groups
Marreiro et al.,³⁵35 Marreiro DN, Geloneze B, Tambascia MA, Lerário AC, Halpern A, Cozzolino SM. Effect of zinc supplementation on serum leptin levels and insulin resistance of obese women. Biol Trace Elem Res. 2006; 112(2): 109-18. 2006	56 obese women, aged 25 to 45, from São Paulo	Biochemical evaluation: plasma zinc, urinary zinc, erythrocyte zinc	Suplementation with zinc versus placebo	-Lack of statistically significant difference between groups in relation to anthropometric and body composition parameters, fasting glycemia, leptin concentrations, and plasma and erythrocyte zinc concentrations -Significant increase in urinary zinc concentration in supplemented women -Significant reduction of insulin concentrations and the Homeostasis Assessment Model Index in supplemented women
Silva et al.,³⁶36 Silva AP, Vitolo MR, Zara LF, Castro CF. Effects of zinc supplementation on 1-to-5-year old children. J Pediatr (Rio J). 2006; 82 (3): 227-31. 2006	58 children, aged 12-59 months, participating in the Governmental Program to Combat Nutritional Deficiencies, living in the city of São Sebastião, DF	Biochemical evaluation: serum zinco	Zinc suplementation versus placebo	-Height and weight growth evolution after supplementation in both groups, but without statistical difference between them -Significant difference in zinc and iron concentrations after supplementation, with higher mean values in the supplemented group
Campos Júnior et al.,³⁷37 Campos Júnior D, Veras Neto MC, Silva Filho VL, Leite MF, Holanda MB, Cunha NF. Zinc supplementation may recover taste for salt meals. J Pediatr (Rio J). 2004; 80 (1): 55-9. 2004	40 under-five children, with lack of appetite for salt meals, assisted at the University Hospital of Brasília, DF	No evaluation	Zinc suplementation versus placebo	-The recovery of appetite for salt meals was significantly higher in children supplemented with zinc than in the placebo group
Al-Sonboli et al.,³⁸38 Al-Sonboli N, Gurgel RQ, Shenkin A, Hart CA, Cuevas LE. Zinc supplementation in Brazilian children with acute diarrhoea. Ann Trop Paediatr. 2003; 23(1): 3-8. 2003	74 children younger than 3 months to 60 months, with acute diarrhea, assisted at emergency services in Aracaju, SE	Biochemical evaluation: serum zinc	Zinc suplementation versus placebo	-Significant reduction in the number of days with diarrhea and liquid stools, number of evacuations, and number of days of hospital stay in the group of children supplemented with zinc, when compared to the placebo group
Chen P et al.,³⁹39 Chen P, Soares AM, Lima AA, Gamble MV, Schorling JB, Conway M, Barrett LJ, Blaner WS, Guerrant RL. Association of vitamin A and zinc status with altered intestinal permeability: analyses of cohort data from north-eastern Brazil. J Health Popul Nutr. 2003; 21 (4): 309-15. 2003	75 children, aged 2 to 97 months, living in the urban area of Fortaleza, CE	Biochemical evaluation: serum zinc	Supplementation with vita-min A versus zinc	-Lack statistically significant difference between serum zinc concentrations and children's age -There was a significant increase in the H/A index after supplementation
Cuevas et al.,⁴⁰40 Cuevas LE, Almeida LM, Mazunder P, Paixão AC, Silva AM, Maciel L, Hart CA, Coulter JB. Effect of zinc on the tuberculin response of children exposed to adults with smear-positive tuberculosis. Ann Trop Paediatr. 2002; 22 (4): 313-9. 2002	98 children, younger than 15 years, exposed to adults with smear-pos-itive pulmonary tubercu-losis, Aracaju, SE	No evaluation	Zinc suplementation versus placebo	-The mean diameter of the hardening area observed in the tuberculin test was significantly higher in children supplemented with zinc than in the placebo group, regardless of the nutritional status evaluated by W/A, H/A, W/H indices
Donangelo et al.,⁴¹41 Donangelo CM, Woodhouse LR, King SM, Viteri FE, King JC. Supplemental zinc lowers measures of iron status in young woman with low iron reserves. J Nutr. 2002; 132 (7): 1860-4. 2002	23 women, aged 20 to 28 years, with low iron stores, but without ane-mia, from Rio de Janeiro, RJ	Biochemical evaluation: plasma zinc, erythrocyte zinc, urinary zinc	Zinc suplementation versus iron	-Increase of plasma, erythrocyte and urinary zinc concentrations after zincsupplementation -Absence of effect on plasma, erythrocyte and urinary zinc concentrations after iron supplementation
Porto et al.,⁴²42 Porto MAS, Oliveira HP, Cunha AJ, Miranda G, Guimarães MM, Oliveira WA, Santos DM. Linear growth and zinc supplementation in children with short stature. J Pediatr Endocrinol Metab. 2000; 13 (8): 1121-8. 2000	18 children, aged 7 to 10 years, with short height, from Rio de Janeiro, RJ	Biochemical evaluation: plasma zinc	Zinc suplementation versus placebo	-Significant increase in growth rate during zinc supplementation that did not persist after discontinuation
Castro et al.,⁴³43 Castro AV, Mendonça BB, Bloise W, Shuhama T, Brandão Neto J. Effect of zinc administration on thyrotropin releasing hormone-stimulated prolactinemia in healthy men. Biometals 1999; 12(4): 347-52. 1999	15 healthy men, with a mean age of 23 years, from São Paulo, SP	Biochemical evaluation: plasma zinc	Supplementation with zinc versus placebo and intra-venous administration of zinc versus placebo	-Significant increase in serum zinc concentrations after oral supplementation and intravenous administration -Lack of effect related to prolactin and thyrotropin-releasing hormone response
Ashworth et al.,⁴⁴44 Ashworth A, Morris SS, Lira PI, Grantham-McGregor SM. Zinc supplementation, mental development and behaviour in low birth weight term infants in northeast Brazil. Eur J Clin Nutr. 1998; 52 (3): 223-7. 1998	205 newborns with low birth weight, born in a hospital in Pernambuco	No evaluation	Supplementation with 1 mg of zinc versus 5 mg of zinc versus placebo	-Absence of significant difference in the mental and psychomotor development scores between groups, after 6 and 12 months of supplementation -Newborns who received 5 mg of zinc showed better behavioral performance than the other groups after 12 months of supplementation
Lira et al.,⁴⁵45 Lira PI, Ashworth A, Morris SS. Effect of zinc supplementation on the morbidity, immune function, and growth of low-birth-weight, full-term infants in northeast Brazil. Am J Clin Nutr. 1998; 68(Supl 2): S418-424. 1998	134 newborns, from birth to 26 weeks of age, from Pernambuco	Assessment of zinc-rich food consumption	Supplementation with 1mg of zinc versus supplementa-tion with 5mg of zinc versus placebo	-Newborns who received 5 mg of zinc showed lower prevalence of diarrhea and cough -Significant effect of zinc supplementation on immune function, occurrence of vomiting, fever, loss of appetite and growth
Marinho et al.,⁴⁶46 Marinho HA, Shrimpton R, Giugliano R, Burini RC. Influence of enteral parasites on the blood vitamin A levels in preschool children orally supplemented with retinol and/or zinc. Eur J Clin Nutr. 1991; 45 (11): 539-44. 1991	471 pre-school children with Ascaris lumbricoides and/or Giardia lamblia enrolled in schools or day care centers in a poor neighborhood of Manaus, AM	Biochemical evaluation: zinc in hair	Supplementation with vitamin A and/or zinc versus placebo	-Significant effect of antiparasitics and supplementation on serum retinol levels

Instituto de Medicina Integral Prof. Fernando Figueira Rua dos Coelhos, 300. Boa Vista, 50070-550 Recife PE Brasil, Tel./Fax: +55 81 2122-4141 - Recife - PR - Brazil
E-mail: revista@imip.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[TFN1] ^*
Results on the prevalence of zinc deficiency with the use of biochemical indicators and/or prevalence of dietary inadequacy of dietary zinc not available in the articles; H/A = Height-for-age; W/H = Weight-for-height; W/A = Weight-for-age.