Vitamin A for preventing acute lower respiratory tract infections in children up to seven years of age

Background Vitamin A supplements are effective for preventing diarrhoea. There are theoretical reasons it might also be effective for acute lower respiratory tract infections (LRTIs), also very common in children, especially in low income countries. Objectives To assess the effectiveness and safety of vitamin A for preventing acute LRTIs in children up to seven years of age. Search strategy We searched the Cochrane Central Register of Controlled Trials ( CENTRAL) ( The Cochrane Library 2007, Issue 2); MEDLINE ( 1966 to July 2007); EMBASE ( 1974 to July 2007); and the Chinese Biomedicine Database (CBM) ( 1976 to July 2007). Selection criteria Randomised controlled trials (RCTs) that assessed the effectiveness of vitamin A in the prevention of acute LRTI in children up to seven years of age. Data collection and analysis The review authors independently extracted data and assessed trial quality. Study authors were contacted for additional information. Main results Most studies found no significant effect of vitamin A on the incidence of acute LRTI, or prevalence of symptoms of acute LRTI. Vitamin A caused an increased incidence of acute LRTI in one study; an increase in cough and fever; and increased symptoms of cough and rapid breathing in two others. Three reported no differences and no protective effect of vitamin A. Two studies reported that vitamin A significantly reduced the incidence of acute LRTI with children with poor nutritional status or weight, but increased it in normal children. Authors' conclusions This unexpected result is outside our current understanding of the use of vitamin A for preventing acute LRTIs. Accordingly, vitamin A should not be given to all children to prevent acute LRTIs. There is evidence for vitamin A supplements to prevent acute LRTIs in children with low serum retinol or those with a poor nutritional status. Acute lower respiratory tract infections (LRTIs), especially pneumonia and bronchiolitis, are leading causes of mortality in children up to five years of age. The Global Burden of Disease 2000 project estimated that the annual number of acute respiratory tract infection (ARTI)-related deaths in children up to five years of age was 2.1 million ( excluding deaths caused by measles, whooping cough and neonatal deaths). Others estimate worldwide child deaths from ARTIs at 1.9 million in 2000, 70% of them in Africa and Southeast Asia. Vitamin A deficiency is common in low income countries and weakens barriers to infection. We included nine trials conducted where vitamin A deficiency or malnutrition is prevalent, including 33,179 children ( 31,379 in the community and 1800 in hospital). Studies measured different things ( what constituted 'acute LRTI'; the time to recall symptoms), and there may have been other treatments ( especially of malnourished children), which could have led to bias. Most studies showed no significant benefit of vitamin A supplement on the incidence or prevalence of symptoms of acute LRTI. No included studies addressed other adverse effects of vitamin A. We do not recommend giving vitamin A to all children to prevent acute LRTIs because a few studies unexpectedly found vitamin A increased the chance of infections or worsened symptoms. Some evidence shows benefit for vitamin supplements given to children with low serum retinol ( or with poor nutritional status).