Pepsin is an enzyme scraped from animal stomachs. It sits next to rennet in the cheese aisle and in a lot of digestive supplements.
Made fromAnimal stomach lining (usually pig)
Used inCheese, supplements, protein hydrolysis
VerdictNot vegan
Where it hides
Some cheeses (with or after rennet)
Digestive enzyme supplements
Protein hydrolysates and collagen products
Some pharmaceuticals
What it is
Pepsin is the enzyme your own stomach uses to start breaking down protein. The commercial version is harvested from animals, whose stomach cells make it in bulk.
Primary source 01 / 01
In the stomach, gastric chief cells release pepsinogen.
Commercial pepsin is usually taken from pig stomachs, a slaughter by-product, and used in some cheeses, in digestive supplements, and to hydrolyse proteins including collagen. Enzyme makers now sell microbial and fungal alternatives, so a supplement or cheese can be made without it, but pepsin itself is an animal product.
RennetTraditional rennet is an enzyme taken from the stomach of a slaughtered calf. Plenty of cheese now uses an animal-free version instead, but the label rarely tells you which, and either way the cheese still contains dairy.
CollagenCollagen is the scaffolding of animal bodies: skin, bone, connective tissue. There is no plant version, so every real collagen supplement is animal-derived, and vegan collagen is a different thing wearing the same name.
GlucosamineThe joint supplement most people reach for is usually built from crab and shrimp shells. A corn-fermented vegan version exists, but it is the exception, so the default bottle is off the menu.
Frequently asked
Is pepsin the same as rennet?
They are both animal enzymes used in cheese, but not identical. Rennet (chymosin) sets the curd, while pepsin is a stronger protein-digesting enzyme sometimes used alongside it. Neither is vegan when animal-derived.
Are there vegan digestive enzymes?
Yes. Many enzyme supplements now use microbial or fungal enzymes rather than pepsin or pancreatin, and say so on the label.
The same clear-eyed sourcing behind these verdicts, applied to each day’s news: what actually moved veganism forward, quoted and checked before you read it. One short brief, free.
