Dr Keith Prowse, British Lung Foundation spokesperson, said:

"This is an interesting study showing an association between diet and the severity levels of asthma among children. Whether this is a direct result of diet or a reflection of other aspects of lifestyle is uncertain and further investigation would be needed for more conclusive evidence. The British Lung Foundation (BLF), the only charity working to support everyone affected by lung disease, would like to reinforce the need for children to have a balanced diet and healthy lifestyle."

Prof Sheila Bird, Programme Leader, MRC Biostatistics Unit, said:

"As ever, association is not causation; and even if diet were directly involved, is it a child's current diet or diet at 2 years of age or at primary school that matters, and how does maternal/paternal diet come into play? Studies like these are a very good way of gathering information but with any study there are limitations and in this case we really need to know more before changing our behaviour."