Soon, a simple blood test may be able to tell whether a person's allergy for peanuts has totally been shut off. Until now, doctors could not test whether patients who had completed immunotherapy for peanut allergy could safely stop eating daily doses of peanuts. Peanut allergy, like other food allergies, currently has no cure. The test would detect the changes in the DNA of the patient's immune cells, according to a new study from the Stanford University and Lucile Packard Children's Hospital Stanford. "Our new finding can help us try to determine whether, for the long term, someone's allergy has truly been shut off so people can eat at their pleasure," said Kari Nadeau, associate professor of paediatrics at Stanford and senior author of the study. Scientists are conducting clinical trials of doctor-supervised immunotherapy, in which peanut-allergic patients take increasing amounts of peanut powder to try to de-sensitise them to the peanut allergen. At the end of the trial, patients are asked to eat some peanuts every day for the rest of their lives. "At first, eating two peanut butter cups a day might seem fun, but it gets a little boring and a lot of people might stop," said Nadeau, an immunologist at Lucile Packard Children's Hospital Stanford. In the new study, Nadeau's team examined 20 peanut-allergic children and adults who had completed two years of immunotherapy, which enabled them to eat one 4-gram serving of peanuts daily without experiencing a major allergic reaction.