title: Prevention of diarrhea and pneumonia by zinc supplementation in children in developing countries: pooled analysis of randomized controlled trials. Zinc Investigators' Collaborative Group.
abstract: OBJECTIVE
  This study assessed the effects of zinc supplementation in the prevention of diarrhea and pneumonia with the use of a pooled analysis of randomized controlled trials in children in developing countries.
  
  
  METHODS
  Trials included were those that provided oral supplements containing at least one half of the United States Recommended Daily Allowance (RDA) of zinc in children <5 years old and evaluated the prevention of serious infectious morbidity through household visits. Analysis included 7 "continuous" trials providing 1 to 2 RDA of elemental zinc 5 to 7 times per week throughout the period of morbidity surveillance and 3 "short-course" trials providing 2 to 4 RDA daily for 2 weeks followed by 2 to 3 months of morbidity surveillance. The effects on diarrhea and pneumonia were analyzed overall and in subgroups defined by age, baseline plasma zinc concentration, nutritional status, and sex. The analysis used random effects hierarchical models to calculate odds ratios (OR) and 95% CIs.
  
  
  RESULTS
  For the zinc-supplemented children compared with the control group in the continuous trials, the pooled ORs for diarrheal incidence and prevalence were 0.82 (95% CI 0.72 to 0.93) and 0.75 (95% CI 0.63 to 0.88), respectively. Zinc-supplemented children had an OR of 0.59 (95% CI 0.41 to 0.83) for pneumonia. No significant differences were seen in the effects of the zinc supplement between the subgroups examined for either diarrhea or pneumonia. In the short-course trials the OR for the effects of zinc on diarrheal incidence (OR 0.89, 95% CI 0.62 to 1.28) and prevalence (OR 0.66, 95% CI 0.52 to 0.83) and pneumonia incidence (OR 0.74, 95% CI 0.40 to 1.37) were similar to those in the continuous trials.
  
  
  CONCLUSIONS
  Zinc supplementation in children in developing countries is associated with substantial reductions in the rates of diarrhea and pneumonia, the 2 leading causes of death in these settings.
authors.affiliation: Aga Khan University Medical Centre, Karachi, Pakistan.
authors.forename: Z A
authors.initials: ZA
authors.lastname: Bhutta
authors.forename: R E
authors.initials: RE
authors.lastname: Black
authors.forename: K H
authors.initials: KH
authors.lastname: Brown
authors.forename: J M
authors.initials: JM
authors.lastname: Gardner
authors.forename: S
authors.initials: S
authors.lastname: Gore
authors.forename: A
authors.initials: A
authors.lastname: Hidayat
authors.forename: F
authors.initials: F
authors.lastname: Khatun
authors.forename: R
authors.initials: R
authors.lastname: Martorell
authors.forename: N X
authors.initials: NX
authors.lastname: Ninh
authors.forename: M E
authors.initials: ME
authors.lastname: Penny
authors.forename: J L
authors.initials: JL
authors.lastname: Rosado
authors.forename: S K
authors.initials: SK
authors.lastname: Roy
authors.forename: M
authors.initials: M
authors.lastname: Ruel
authors.forename: S
authors.initials: S
authors.lastname: Sazawal
authors.forename: A
authors.initials: A
authors.lastname: Shankar
mesh_terms: D002648:Child; D003906:Developing Countries; D003967:Diarrhea / Q000517:prevention & control*; D019587:Dietary Supplements; D006801:Humans; D011014:Pneumonia / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D015032:Zinc / Q000627:therapeutic use*
chemical_list: D015032:Zinc