Carbonated drink consumption and increased exhaled nitric oxide in atopic children

To the Editors: Fractional exhaled nitric oxide concentrations ( F eNO) are elevated in asthmatic children and have been used inter alia to guide inhaled corticosteroid treatment in children 1. Caffeine consumption might influence F eNO independently of asthma and more than one plausible mechanism has been identified. Studies in adults have reported changes in F eNO within 1 h of caffeine ingestion but the results are inconsistent, with one study having reported reduced F eNO 2, one elevated F eNO 3 and another no change after ingestion 4. An association between caffeine intake and altered F eNO is equally plausible in children but has not been sought. The predominant source of caffeine in children’s diet is carbonated drinks, in particular colas, and in Scotland “Irn Bru” (a carbonated orange-coloured drink). …