When 15 year old Natasha Ednan-Laperouse died after eating a baguette from Pret containing sesame seeds, a campaign to get better food labelling was launched. Now the Government has started a consultation into strengthening current labelling laws to protect allergy sufferers. But are we getting more allergic to food and what scientific research is being done to find out why some people have more extreme reactions than others? The BBC’s health and science correspondent James Gallagher takes us through the biology.

Mixed by Weidong Lin, additional mixing by Nicolas Raufast.