The authors of this systematic review and meta analysis found that in low and middle income countries vitamin A supplementation is associated with a 24% reduction in mortality and also prevents blindness. The authors reviewed all available evidence for vitamin A supplementation in children aged 6 months to 5 years to determine if supplementation is associated with reductions in mortality and morbidity in this age group. They included randomised trials of synthetic oral vitamin A supplements in the age group studied and overall 43 trials with approximately 215,633 children were included in the review. Studies of children with current illness (such as diarrhoea, measles, and HIV) or children in hospital, and studies of food fortification or beta carotene were excluded from the review. The results found (direct from source):

• Seventeen trials including 194,483 participants reported a 24% reduction in all cause mortality (rate ratio=0.76, 95% confidence interval 0.69 to 0.83).

• Seven trials reported a 28% reduction in mortality associated with diarrhoea (0.72, 0.57 to 0.91).

• Vitamin A supplementation was associated with a reduced incidence of diarrhoea (0.85, 0.82 to 0.87) and measles (0.50, 0.37 to 0.67) and a reduced prevalence of vision problems, including night blindness (0.32, 0.21 to 0.50) and xerophthalmia (0.31, 0.22 to 0.45).

• Three trials reported an increased risk of vomiting within the first 48 hours of supplementation (2.75, 1.81 to 4.19).

The authors note that the evidence for vitamin A is compelling and clear and add that further trials comparing vitamin A with placebo in the age group studied would therefore be unethical. However, they acknowledge that their review does not identify the most effective dose or mechanism of delivery. The authors conclude, “There is a need for further studies comparing different doses and delivery mechanisms (for example, fortification). Until other sources are available, vitamin A supplements should be given to all children at risk of deficiency, particularly in low and middle income countries.”

The authors of a related editorial discuss the results of the review and note that although it represents an advance in helping to clarify the effects of vitamin A on mortality and morbidity, some questions remain. The editorialists write, “As previous meta-analyses have stated, no more placebo controlled trials of preschool vitamin A supplementation are needed. Instead, effort should focus on finding ways to sustain this important child survival initiative and fine tune it to maximise the number of lives saved”.