Traditional rennet is not vegan. It is extracted from the stomach lining of young calves. Cheeses labelled with microbial rennet, vegetable rennet, or fermentation-produced chymosin (FPC) avoid the animal source, but all rennet-set cheese contains dairy and requires separate vegan certification.

Traditional rennet is not vegan because it is taken from the stomach lining of young calves. Microbial rennet and fermentation-produced chymosin are not animal-derived, but the cheese made with them still contains dairy and is only vegan when the final product is explicitly labelled vegan.

What cheeses are made with animal rennet?

Most protected traditional cheeses, including Parmigiano Reggiano, Grana Padano, Pecorino Romano, Gruyere, and many farmhouse cheddars. Production rules for some of these require animal rennet by law.

Is Rennet Vegan? | Find Feny Library

Traditional rennet is not vegan. It is an enzyme taken from the stomach lining of young calves and used to coagulate milk for cheese. Microbial and fermentation-produced alternatives exist but are not always disclosed.

Why It's Confusing

Rennet is a coagulant, not a flavour ingredient, so it rarely appears on menus and is often omitted from front-of-pack labelling. There are four sources in commercial use: animal rennet from calf stomachs, microbial rennet from moulds such as Rhizomucor miehei, fermentation-produced chymosin from genetically modified microorganisms [[3]](#source-3), and plant-derived coagulants such as thistle used in a small number of Iberian cheeses.

Protected-name cheeses are the clearest case. Parmigiano Reggiano production rules require calf rennet [[2]](#source-2), and Grana Padano and Pecorino Romano follow the same tradition. Even when a cheese uses a non-animal coagulant, it is still made from milk, so a vegetarian-friendly cheese is not automatically vegan [[4]](#source-4). See casein and whey for the dairy side of the same product.

Where It Commonly Appears

Hard Italian cheeses (Parmigiano Reggiano, Grana Padano, Pecorino Romano)
Traditional Swiss and French cheeses (Gruyere, Comte, Roquefort)
Farmhouse and traditional cheddars
Restaurant cheese boards, pizza toppings, pasta finishes, and grated cheese
Whey-based protein powders derived from rennet-set cheese production

Anywhere restaurant cheese appears without specific labelling, the default assumption is animal rennet unless the venue states otherwise.

What To Watch For

"Rennet" on a label, with no qualifier, usually means animal rennet
"Microbial rennet", "vegetable rennet", "non-animal rennet", or "fermentation-produced chymosin" are not animal-derived, but the cheese is still dairy
Protected-name cheeses (PDO / DOP) may be bound by rules requiring animal rennet [[2]](#source-2)
Vegetarian symbols on cheese indicate no animal rennet but do not indicate vegan status [[4]](#source-4)
Restaurant menus rarely specify the rennet source, so cheese should be treated as animal-rennet by default

Vegan Alternatives

Plant-based cheeses with explicit vegan certification
Cashew, almond, and soy-based cheeses from brands such as Violife, Miyoko's Creamery, and Nurishh
Nutritional yeast as a parmesan substitute
Dishes prepared without cheese, requested specifically rather than relying on default menu labelling