Vitamin A status in children who are prone to respiratory tract infections

The effect of Vitamin A supplementation on susceptibility to acute respiratory infections was investigated in a randomized controlled trial. One hundred and forty-seven preschool-age children with a history of frequent respiratory illness were randomized into Vitamin A supplemented (450 micrograms/day) and placebo groups. Respiratory symptoms were recorded on a daily basis over a period of 11 months. The children who received the supplement experienced 19% fewer episodes of respiratory symptomatology (P less than 0.05) than their placebo counterparts, despite the fact that their plasma retinol levels did not change. Children with a prior history of lower respiratory illness or of allergy benefited most from supplementation. The plausibility of a role for Vitamin A in the aetiology of respiratory proneness is reviewed.