Vitamin A for preventing acute lowe respiratory tract infections in children up to 7 years of age.  Chen H. 2008 [43]  Children from areas or with conditions correlated with a status of vitamin A deficiency.10 RCTs  Vitamin A (6 studies were large-dose trials (100,000 UI o 200,000 UI) 4 studies were low-dose trials (5000 UI daily or 10,000 UI weekly or 45,000 UI every 2 months)  No significant effect on the incidence or prevalence of ALRI symptoms with vitamin A supplementation.