Isinglass is fish. It is a collagen made from dried swim bladders and used to clarify some beers and wines, which is why a plain-looking pint can fail the vegan test.
Made fromDried fish swim bladders
Used asFining agent in beer and wine
VerdictNot vegan
Where it hides
Cask and some real ales
Some wines and ciders
Rarely printed on the label (a processing aid)
What it is
Isinglass is a form of collagen made from the dried swim bladders of fish. Brewers and winemakers add it as a fining agent: it drags yeast and haze to the bottom so the liquid pours bright and clear. Most of it settles out and is removed, but it is an animal product used in the making, so a beer or wine fined with isinglass is not vegan even though the finished drink contains little to none of it.
Why it is hard to spot
Fining agents count as processing aids, not ingredients, so they usually never appear on the bottle. That is why a lager can be vegan and the cask ale next to it is not. The reliable move is to check a vegan drinks directory or the producer's own statement. The picture does change over time: Guinness phased isinglass out of its filtration and is now vegan-friendly.
GelatinGelatin is boiled animal collagen, usually from pig or cow skin and bone. There is no plant version; the plant swaps are agar, pectin and carrageenan.
Carmine and cochineal (E120)That bright natural red in the yogurt or the candy is often crushed insects. Carmine, cochineal extract, Natural Red 4, E120: all the same animal dye.
BeerMost beer is just grain, hops, water and yeast, which sounds vegan and often is. The complication is what happens after brewing: some beers are cleared with fish, and the label rarely tells you.
Frequently asked
Does isinglass mean beer is not vegan?
Beer fined with isinglass is not vegan, but many beers are not fined this way. Bottled and canned lagers are frequently vegan, while traditional cask ales are the most likely to use isinglass. A vegan drinks directory is the quickest check.
Is wine vegan?
It depends on the fining. Some wines are fined with isinglass, gelatin, egg white or casein, and some are unfined or use plant or mineral finings. The label rarely says, so look for a vegan mark or the winery's statement.
The sources
What each verdict rests on. Read them yourself.
Isinglass (compound summary) · PubChem, US National Library of Medicine (NIH), 2024 · NIH chemical database, identity and fish-collagen origin
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