eg in red/white wine, fruit juices, some processed foods eg GF beef burgers/ GF bread?
"Sulphites are naturally occurring substances found in some food and drink. They are also sometimes used as a food preservative. Food and drinks that are high in sulphites include concentrated fruit juice, jam, prawns and many processed or pre-cooked meals. Most people with asthma do not have this trigger, but some may. Certain wines can also trigger asthma in susceptible people."