"Though the ‘girders’ were often thought to be a reference to the ‘rust’ colour of the drink, Irn Bru does have 0.002 per cent ammonium ferric citrate listed am

"Though the ‘girders’ were often thought to be a reference to the ‘rust’ colour of the drink, Irn Bru does have 0.002 per cent ammonium ferric citrate listed among its ingredients – a food additive containing iron hydroxide." https://foodanddrink.scotsman.com/drink/16-facts-about-irn-bru/ https://foodanddrink.scotsman.com/drink/16-facts-about-irn-b...