Isinglass, a gelatin-like substance made from dried fish swim bladders, is used across the brewing industry to filter unwanted solids such as yeast particles from beer.
Although only trace amounts of isinglass remained in its drinks, the 256-year old company has been unable to label its products as vegetarian-friendly.
“Isinglass has been used widely within the brewing industry as a means of filtration for decades,” a spokesperson for the company said in a statement.
“However, because of its use we could not label Guinness as suitable for vegetarians and have been looking for an alternative solution for some time."
Guinness has invested in a new state-of-the-art filtration system at its St James’s Gate headquarters in Dublin which will eradicate the need for isinglass.
The new system is set to start rolling out early in 2016.
Vegetarian and vegan drinkers have long called for isinglass to be phased out of the brewing industry.
“We are always happy to see another product become suitable for vegans, especially because this one is very iconic here in Ireland,” Edmund Long, a spokesperson for Vegan Ireland, told the New York Times.
“It’s one of the products you associate with Ireland; Guinness is usually up there.”