Supplementing iron and zinc: double blind, randomized evaluation of separate or combined delivery

Eur J Clin Nutr. 2010 Feb;64(2):153-60. doi: 10.1038/ejcn.2009.127. Epub 2009 Nov 11.


Background/objectives: Many children have diets deficient in both iron and zinc, but there has been some evidence of negative interactions when they are supplemented together. The optimal delivery approach would maximize clinical benefits of both nutrients. We studied the effectiveness of different iron and zinc supplement delivery approaches to improve diarrhea and anemia in a rural Bangladesh population.

Study design: Randomized, double blind, placebo-controlled factorial community trial.

Results: Iron supplementation alone increased diarrhea, but adding zinc, separately or together, attenuated these harmful effects. Combined zinc and iron was as effective as iron alone for iron outcomes. All supplements were vomited <1% of the time, but combined iron and zinc were vomited significantly more than any of the other supplements. Children receiving zinc and iron (together or separately) had fewer hospitalizations. Separating delivery of iron and zinc may have some additional benefit in stunted children.

Conclusions: Separate and combined administration of iron and zinc are equally effective for reducing diarrhea, hospitalizations and improving iron outcomes. There may be some benefit in separate administration in stunted children.

Publication types

  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anemia, Iron-Deficiency / complications
  • Anemia, Iron-Deficiency / drug therapy*
  • Deficiency Diseases / drug therapy*
  • Diarrhea / epidemiology
  • Diarrhea / etiology
  • Diarrhea / prevention & control
  • Dietary Supplements*
  • Double-Blind Method
  • Drug Therapy, Combination
  • Female
  • Growth Disorders / drug therapy*
  • Hospitalization
  • Humans
  • Incidence
  • Infant
  • Iron / adverse effects
  • Iron / deficiency
  • Iron / therapeutic use*
  • Male
  • Vomiting
  • Zinc / deficiency
  • Zinc / pharmacology
  • Zinc / therapeutic use*


  • Iron
  • Zinc