It is often called Scotland’s favourite beverage, with a distinctive caramel colour and heady taste derived from a 106-year-old recipe.
So it comes as no surprise that attempts to meddle with the ingredients of Irn-Bru have prompted outrage.
More than 9,000 people have signed a “Hands off our Irn-Bru” petition objecting to an imminent reduction to its sugar content, and consumers are reportedly stockpiling the original version of the fizzy drink.
Historically Irn-Bru has contained a tooth-tingling 10% of sugar, but manufacturers plan to halve that – replacing it with artificial sweeteners such as aspartame from January.
The decision, linked to a government tax on sugar to be introduced in April and a consumer shift towards products low in sugar, will drop the number of calories in a can from 140 to 65.
It follows similar moves in the recipes of other drinks including Lucozade.
But Ryan Allen, who started the petition, does not believe less is more.
His Change.org page voices fears over the impact of aspartame and argues he would pay more for Scotland’s high-sugar “national treasure”.
“I believe that a responsible adult should have the choice as to what poisons they want to put in their body,” he says.
“It’s also well known to alleviate the effects of a hangover and is many a person’s craving, saviour or go-to drink after a night on the tiles. I think to deny people in that condition their crutch would be a crime.”
His sentiments were reflected on Twitter – with one fan declaring “this can git tae France” and dozens more pledging to stockpile the sugary version.
Can’t believe Irn Bru are changing the recipe, are you mad? I’m going costco and stocking up. Half the sugar? nope not for me.
— Freezy (@Calfreezy) 4 January 2018
Consultant dietitian Rebecca McManamon, a spokesperson for the British Dietetic Association, said reducing sugar content could help slash the incidence of diabetes, obesity and tooth decay.
She told Sky News that high-sugar drinks would only be recommended for people with diabetes who need a sugar boost.
“There is no benefit if you’re feeling run down to have a sugary drink,” she said. “Even if you get a temporary reprieve, you’re going to have a drop in energy afterwards.”
Aspartame, she said, would likely only pose a danger if many litres of Irn-Bru were being consumed.
Irn-Bru’s manufacturer, AG Barr, has insisted that nine in ten people could not tell the difference between high and low-sugar versions.
“The vast majority of our drinkers want to consume less sugar so that’s what we’re now offering,” a spokesperson said.