OBJECTIVES : Our aim was to investigate the effect of iron supplements or iron-fortified foods on diarrhea in infants younger than 1 year of age

METHODS : Randomized controlled studies related to iron supplementation in infants were searched in PubMed, Cochrane, and Web of Science databases and CNKI, and Chinese Biomedical Literature databases. The publication date of the literature is from the self-built database to November 2020. At the same time, the clinical trial register platform (https://clinicaltrials.gov/) and Chinese clinical trial register platform (www.chictr.org.cn) were also searched in order to get a more comprehensive result. Data extraction and bias risk assessment were conducted independently by two investigators and statistical analysis was performed using STATA15.0. All randomized controlled trials examining the association between iron supplementation and diarrhea in infants under 1 years of age were included .We evaluated the methodological quality of the included studies, and data that met the inclusion criteria were extracted for meta-analysis using STATA 15.0 software.

RESULTS : A total of 1,809 infants were included in five randomized controlled trials. Results of the meta-analysis showed no significant difference in diarrhea events between the iron supplementation group and the control group (RR=1.056,95%CI (0.8744-1.275),P=0.573). There was no statistically significant difference in diarrhea events between 1 mg/kg/d and 2.5 mg/kg/d iron supplements (RR=1.06,95%CI 0.87-1.27).

CONCLUSIONS : Small doses of iron supplements do not increase the risk of diarrhea in healthy infants under 1 year of age.