Micronutrient-fortified rice can increase hookworm infection risk: a cluster randomized trial

Brechje de Gier, Maiza Campos Ponce, Marlene Perignon, Marion Fiorentino, Kuong Khov, Chhoun Chamnan, Michiel R de Boer, Megan E Parker, Kurt Burja, Marjoleine A Dijkhuizen, Jacques Berger, Katja Polman, Frank T Wieringa

    Research output: Contribution to journalA1: Web of Science-articlepeer-review

    23 Downloads (Pure)


    BACKGROUND: Fortification of staple foods is considered an effective and safe strategy to combat micronutrient deficiencies, thereby improving health. While improving micronutrient status might be expected to have positive effects on immunity, some studies have reported increases in infections or inflammation after iron supplementation.

    OBJECTIVE: To study effects of micronutrient-fortified rice on hookworm infection in Cambodian schoolchildren.

    METHODS: A double-blinded, cluster-randomized trial was conducted in 16 Cambodian primary schools partaking in the World Food Program school meal program. Three types of multi-micronutrient fortified rice were tested against placebo rice within the school meal program: UltraRice_original, UltraRice_improved and NutriRice. Four schools were randomly assigned to each study group (placebo n = 492, UltraRice_original n = 479, UltraRice_improved n = 500, NutriRice n = 506). Intestinal parasite infection was measured in fecal samples by Kato-Katz method at baseline and after three and seven months. In a subgroup (N = 330), fecal calprotectin was measured by ELISA as a marker for intestinal inflammation.

    RESULTS: Baseline prevalence of hookworm infection was 18.6%, but differed considerably among schools (range 0%- 48.1%).Micronutrient-fortified rice significantly increased risk of new hookworm infection. This effect was modified by baseline hookworm prevalence at the school; hookworm infection risk was increased by all three types of fortified rice in schools where baseline prevalence was high (>15%), and only by UltraRice_original in schools with low baseline prevalence. Neither hookworm infection nor fortified rice was related to fecal calprotectin.

    CONCLUSIONS: Consumption of rice fortified with micronutrients can increase hookworm prevalence, especially in environments with high infection pressure. When considering fortification of staple foods, a careful risk-benefit analysis is warranted, taking into account severity of micronutrient deficiencies and local prevalence of parasitic infections.

    TRIAL REGISTRATION: ClinicalTrials.gov NCT01706419.

    Original languageEnglish
    Article numbere0145351
    JournalPLoS ONE
    Issue number1
    Number of pages12
    Publication statusPublished - 2016


    • Ancylostomatoidea
    • Animals
    • Child
    • Double-Blind Method
    • Enzyme-Linked Immunosorbent Assay
    • Feces
    • Female
    • Food, Fortified
    • Humans
    • Intestinal Diseases, Parasitic
    • Iron, Dietary
    • Leukocyte L1 Antigen Complex
    • Longitudinal Studies
    • Male
    • Micronutrients
    • Oryza
    • Placebo Effect
    • Prevalence
    • Clinical Trial
    • Journal Article
    • Randomized Controlled Trial
    • Research Support, Non-U.S. Gov't
    • Research Support, U.S. Gov't, Non-P.H.S.


    Dive into the research topics of 'Micronutrient-fortified rice can increase hookworm infection risk: a cluster randomized trial'. Together they form a unique fingerprint.

    Cite this