You did ask Horsie, more info than you want I fear !!!!!!!!!
Irn-Bru (pronounced iron brew, IPA: /ˈaɪɚn ˈbruː/) is a popular carbonated soft drink produced in Scotland. It is made by A.G. Barr plc, of Cumbernauld. Barr's Irn-Bru is available in the United Kingdom, the Republic of Ireland, Gibraltar, Russia, Canada, Norway, South Africa, Singapore, parts of Europe such as Poland, the Middle East, in some parts of Australia (introduced in 2006), New Zealand (introduced in 2007) and in the United States.
Irn-Bru is famous for its bright orange colour (something it shares with the glucose drink Lucozade). As of 1999 it contained 0.002% of ammonium ferric citrate, sugar, 32 flavouring agents (including caffeine—though caffeine is not listed as an ingredient on the Australian labelling—and quinine) and two controversial colourings (E110, E124). It is advertised as having a slight citrus flavour, but many have differing opinions of the exact taste of Irn-Bru. One of the key ingredients is said to be barley while another rumour holds that seaweed is a major contributor to the taste[citation needed].
Irn-Bru was first produced in 1901, under the name Iron Brew. In 1946, a change in laws required that the word "brew" be removed from the name, as the drink is not technically brewed. Interestingly Morrisons now produce and sell a product with that very name, which is designed to taste similar to the original. The chairman of the company came up with the idea of changing both halves of the name to a phonetic spelling, giving the current Irn-Bru brand. 1980 saw the introduction of Low Calorie Irn-Bru; this was re-launched in 1991 as Diet Irn-Bru and the Irn-Bru 32 energy drink variant was launched in 2006. All the rumour and folklore surrounding Irn-Bru only serve to help keep it in its place as an icon of Scottish popular culture.
It has long been the most popular soft drink in Scotland, outselling Coca-Cola, but recent fierce competition between the two brands has brought their sales to roughly equal levels (perhaps leaning to Coca-Cola).[1] It is also the third best selling soft drink in the UK, after Coca-Cola and Pepsi, outselling high-profile brands such as Tango, Fanta, Dr Pepper, Sprite and 7-Up. This success in defending its home market (a feat claimed only by Irn-Bru, Brazil's Guaranį, South Australia's Farmers Union Iced Coffee, Peru's Inca Kola, Malta's Kinnie and Sweden's Julmust) has led to ongoing speculation that Coca-Cola, PepsiCo, Inc. or its UK brand franchisee Britvic, would attempt to buy A.G. Barr
Irn-Bru's advertising slogans used to be "Scotland's other National Drink", referring to whisky, and "Bru'd in Scotland from girders", though the closest one can come to substantiating this claim is the 0.002% ammonium ferric citrate listed in the ingredients.