Why Isn't Guinness Vegetarian? The Truth About the Iconic Stout

December 2, 2025 •

4 min read

For over 250 years, the iconic Irish stout was not considered vegetarian, a fact that surprised many drinkers unaware of a specific animal-derived ingredient used in its production. This was because the brewing process traditionally involved a fining agent sourced from fish. So why isn't Guinness vegetarian and has this changed?

Quick Summary

Historically, Guinness was not vegetarian due to the use of isinglass, a clarifying agent made from fish bladders. The brewery implemented a new filtration system to remove this animal-derived ingredient, making the product suitable for both vegetarians and vegans as of 2017/2018.

Key Points

Traditional Ingredient: Historically, Guinness was not vegetarian due to the use of isinglass, a clarifying agent made from the swim bladders of fish.
Filtration, Not Flavor: Isinglass was used to filter out yeast and sediment, not as a flavor ingredient, but traces could remain.
Vegan-Friendly Shift: In 2015, Guinness announced plans to transition to a new, non-animal filtration process.
Global Availability: By 2018, all Guinness products, including draught, bottles, and cans, were vegan-friendly and isinglass-free worldwide.
Taste Unchanged: The move to the new filtration method did not impact the iconic taste or recipe of Guinness.
Modern Alternatives: Brewers now use modern vegan filtration methods, such as silica gel and physical filters, to achieve the same clarity without animal products.
Meeting Consumer Demand: The change reflects Guinness's response to a growing demand for ethical and plant-based food and drink options.

The Surprising Animal Product in Traditional Guinness

For centuries, the brewing industry, including Guinness, relied on a compound called isinglass to clarify its beers. This gelatinous substance, derived from the swim bladders of fish like sturgeon and Nile perch, was a highly effective fining agent. Its purpose was not to alter the flavor but to expedite the process of sedimentation, causing stray yeast particles and other cloudy solids to clump together and settle at the bottom of the vats. This created the clear, ruby-red liquid visible in a well-poured pint.

Although the isinglass itself is filtered out during production, minute traces could potentially remain in the final product. For strict vegetarians and vegans, even this minimal contact with an animal-derived substance rendered the beer unsuitable for consumption. This was a significant consideration for many, leading to a long-standing debate within the vegetarian and vegan communities about the ethics of drinking Guinness.

The Shift to a Vegan-Friendly Process

Recognizing the growing demand for vegetarian and vegan-friendly products, Guinness's parent company, Diageo, announced in 2015 its plans to remove isinglass from its brewing process. After several years of research and development, which involved investing in a new, state-of-the-art filtration system, the company made the change. The new system, which uses a non-animal-derived process, achieves the same clarifying effect without compromising the beer's quality, taste, or iconic appearance.

The transition timeline to vegan Guinness

November 2015: Diageo announces its intention to stop using isinglass.
Early 2016: A new, isinglass-free filtration process is implemented for all draught Guinness kegs.
By 2017: The new filtration system is fully rolled out, making draught Guinness worldwide suitable for vegans and vegetarians.
2018: Diageo confirms that all Guinness products, including those in cans and bottles, are now isinglass-free.

Traditional Fining vs. Modern Vegan Alternatives

The brewing world has a long history of using fining agents to enhance beer clarity. While isinglass was a traditional and highly effective choice, modern technology has provided brewers with numerous animal-friendly alternatives.


Feature	Traditional Isinglass Fining	Modern Vegan Filtration
Primary Agent	Collagen from fish swim bladders	State-of-the-art filters, silica gel, or PVPP
Method	Added to the beer to bond with yeast and proteins, causing them to settle	Physical filtration using advanced equipment and/or adsorbent chemicals
Ethical Consideration	Not vegetarian/vegan due to animal-derived source	Fully vegetarian and vegan-friendly
Speed	A relatively quick clarifying method	Can be slower, but modern technology has increased efficiency
Taste Impact	Can sometimes strip certain flavor compounds from the beer	Minimizes taste impact while maintaining the beer's intended flavor profile

Does the Change Affect the Taste of Guinness?

One common concern among loyal Guinness drinkers was whether the removal of isinglass would alter the flavor profile of the beloved stout. The company has repeatedly assured consumers that the iconic taste of Guinness remains unchanged. The switch to a modern filtration system did not require any alteration to the original recipe, which consists of four main ingredients: roasted barley, malted barley, hops, yeast, and water. The new technology simply replaces the traditional clarifying process with an equally effective but animal-free method.

The Bottom Line: Is Guinness Vegetarian Now?

The answer is yes. Since 2018, all Guinness products, including draught, bottles, and cans, have been completely vegetarian and vegan-friendly. The change is a testament to the company's responsiveness to consumer demand and the evolving landscape of ethical food production. For those who had previously avoided the drink due to its historical use of isinglass, a pint of Guinness can now be enjoyed guilt-free.

Conclusion: A Toast to Change

The story of Guinness's transformation from a non-vegetarian product to a vegan-friendly one is a prime example of how major corporations can adapt to meet the ethical considerations of modern consumers. The old tradition of using isinglass has been replaced with modern filtration techniques that maintain the product's renowned quality while aligning with the values of a growing number of people. So, the next time you raise a glass, you can rest assured that your pint is made without any animal-derived fining agents. This shift proves that tradition and innovation can coexist, creating a more inclusive product for everyone. You can read more about Guinness's brewing process on their official website for additional details.

Is Guinness Vegetarian?

Old Process: Guinness was not vegetarian due to the use of isinglass, a fish-derived clarifying agent.
Ingredient Replacement: The brewing recipe itself did not contain animal ingredients, but the filtration process did.
Vegan Transition: In 2015, Guinness announced plans to move to a new filtration system to eliminate isinglass.
Current Status: All Guinness products worldwide have been vegetarian and vegan since 2018.
No Taste Change: The switch to a vegan-friendly process did not alter the famous taste or recipe of the stout.

Frequently Asked Questions

Yes, as of 2018, all Guinness products sold worldwide are vegetarian and vegan. The company removed the animal-derived fining agent isinglass from its filtration process.

Isinglass is a gelatinous substance derived from the swim bladders of certain fish, traditionally used in brewing and winemaking to clarify and remove haze from the liquid.

Guinness and many other traditional brewers used isinglass to speed up the fining process. The positively charged isinglass attracts negatively charged yeast and protein particles, causing them to clump together and settle faster.

No, according to Guinness and its parent company Diageo, the change in the filtration process did not alter the beer's original recipe or taste. Only the filtering agent was changed.

Guinness draught beer became vegan-friendly in 2017, with the transition for bottled and canned products completed by 2018, at which point all Guinness products were fully vegan.

Yes, all Guinness products worldwide, including draught, bottles, and cans of Guinness Draught, Guinness Original, and Guinness Foreign Extra Stout, are now made without animal products.

Brewers use modern, non-animal-derived filtration methods, such as mechanical filters, centrifugal separators, and fining agents like silica gel or PVPP, to achieve clear beer.