28 August 2009

Zinc and copper not effective for acute diarrhea

Purpose of study: Zinc and copper are lost in significant amounts in acute diarrhea and zinc has been suggested as a therapy for its possible facilitation of water and electrolyte transport across intestinal mucosa to prevent villous atrophy and modulate immune response. This study evaluated whether or not zinc and copper supplementation had any beneficial effect on acute watery or bloody diarrhea when given with standard treatment.

Type of study: Randomized, double-blinded placebo-controlled trial

Method used to conduct study: Children ages 6-59 months with acute diarrhea were given standard treatment and randomized to placebo, zinc only (Zn 20mg/5ml elemental zinc), or zinc and copper (2mg/5ml of elemental copper) together via syrup. There were 808 children chosen for the study out of 1,200 screened over the period of Aug 2003 and Oct 2006. Each provided more than three stool samples in prior 24 hours, who had duration of diarrhea for up to 72 hours and who were able to orally accept fluid or food. Exclusions were those with positive HIV, kwashiorkor or participating in another study.

Summary: There was no observed impact on duration or total stool output in acute diarrhea found between the groups supplemented with zinc only, zinc and copper, or placebo. No serious adverse events were associated with the three syrups. Critique: Measures were taken in this study to ensure quality control and appropriate data analysis and interpretation. The quality of the study make its results valid given the amount of subjects and assessment of the data.

Nutritional implications and implications of future study: The researchers offered that the lack of effect would not have been due to low dose, poor adherence to treatment or failure to replenish zinc loss. They did offer that extent of zinc deficiency in study populations could be why other studies showed therapeutic benefits from zinc, but that not all therapeutic studies reported benefits of zinc in children with deficiency. Therapeutic supplementation with zinc may, in fact, depend on diarrhea etiology at different ages in populations. There may also have been interaction with zinc and the standard treatment, which included a multivitamin with vitamin A and B vitamins. Future study may need to evaluate zinc supplementation with different etiologies for diarrhea and separately with regards to multivitamin interaction.

Reference: Patel A, Dibley MJ, Mamtani M, Badhoniya N, Kulkarni H. Zinc and copper supplementation in acute diarrhea in children: a double-blind randomized controlled trial. BMC Med 2009;7:22. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=19416499

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