WHEN you have a child with food allergies, the fear of a severe reaction is always there, says Emma Amoscato. “It’s not just mealtimes, it’s going to nursery, family events, soft play. It’s not something you can ever take a day off from.”

She is frustrated that some children, such as hers, could perhaps have avoided developing their allergies at all. A growing body of evidence, including findings that emerged last month, suggests that the earlier babies eat foods like peanuts …