Why Can't Vegetarians Eat Cheese? The Hidden Ingredient Explained

According to a 2021 study, the global vegetarian cheese market is expected to grow significantly, yet many vegetarians still don't know why some traditional cheeses are off-limits. The issue lies with a hidden animal-derived ingredient called rennet, a key component in many cheese-making processes.

Quick Summary

The primary reason some cheese is not vegetarian is the use of animal rennet, an enzyme from the stomach lining of young mammals like calves. This ingredient helps coagulate milk to form cheese curds. Alternatives like microbial or plant-based rennet are available, but not all cheeses use them. Consumers should check labels for specifics.

Key Points

• Animal Rennet: The primary reason some cheese isn't vegetarian is the use of animal rennet, an enzyme from the stomachs of slaughtered young mammals like calves.

• Vegetarian Alternatives: Modern cheese is often made with microbial rennet, plant-based rennet, or fermentation-produced chymosin (FPC), which are all vegetarian-friendly.

• Labeling is Key: To identify a vegetarian cheese, check labels for specific terms like 'microbial enzymes' or 'vegetarian rennet,' as the type of coagulant is often listed.

• Protected Cheeses: Some traditional European cheeses like Parmigiano-Reggiano and Gruyère legally mandate the use of animal rennet and are never vegetarian.

• Kosher Certification: A reliable indicator of vegetarian cheese is a kosher certification (like a 'K' or 'OU'), as kosher rules prevent mixing meat and dairy.

• Soft Cheeses: Fresh, soft cheeses like paneer, ricotta, and cottage cheese typically use acid (not rennet) for coagulation and are safe bets for vegetarians.

The Hidden Animal Byproduct: Understanding Animal Rennet

For many vegetarians, the line between animal-based and plant-based foods can seem clear. However, when it comes to cheese, the distinction is blurred by a common, yet often misunderstood, ingredient: rennet. Rennet is a complex of enzymes used to coagulate milk, separating it into solid curds and liquid whey. This process is critical for creating most types of cheese. The source of this rennet determines whether the final product is suitable for a vegetarian diet.

Where Animal Rennet Comes From

Traditional animal rennet is an extract from the fourth stomach lining (the abomasum) of young, unweaned ruminant animals, most commonly calves. These animals are typically slaughtered for veal, and the rennet is extracted as a byproduct of the meat industry. The use of this ingredient, derived from a slaughtered animal, makes any cheese containing it non-vegetarian by most standards.

The Vegetarian Alternatives to Animal Rennet

Fortunately for vegetarians and cheese lovers alike, there are several alternatives to traditional animal rennet. Modern cheesemaking has developed various coagulants that perform the same function without relying on animal slaughter. These options have made it possible for a wide range of cheeses to be vegetarian-friendly.

Common Vegetarian-Friendly Coagulants

• Microbial Rennet: This is the most common and widely used alternative in commercial cheesemaking. It is produced by fermenting specific fungi, such as Rhizomucor miehei, and is a reliable and consistent option. Early versions sometimes imparted a bitter flavor to aged cheeses, but modern improvements have largely eliminated this issue.
• Fermentation-Produced Chymosin (FPC): FPC is a genetically engineered version of chymosin, the key enzyme in calf rennet. It is produced by introducing the gene for chymosin into microorganisms like yeast or bacteria, which then produce the enzyme through fermentation. The resulting chymosin is identical to the animal version, but no animals are involved in its production. FPC is widely used in the United States and accounts for a significant portion of global cheese production.
• Plant-Based Rennet: Sourced from plants with natural coagulating properties, such as artichoke thistle, fig leaves, or nettles. This type is less common in mass production due to potential flavor inconsistencies but is used in some traditional and artisanal cheeses, particularly in Mediterranean regions.
• Acid Coagulants: Some cheeses are made without any rennet at all, relying instead on acid, such as lemon juice or vinegar, to curdle the milk. These are typically softer cheeses and are almost always vegetarian, though still contain dairy. Examples include paneer, cottage cheese, and some fresh ricotta.

Identifying Vegetarian Cheese in Stores

It can be challenging to determine a cheese's rennet source, as labeling regulations vary. Many countries do not require manufacturers to specify the type of enzyme used. However, there are several clues and indicators to look for:

• Read the Label: Look for phrases like "microbial enzymes," "vegetarian rennet," or "non-animal rennet". If the label simply says "enzymes" without further clarification, it is best to assume it contains animal rennet unless certified otherwise.
• Seek Kosher Certification: Because Jewish dietary laws prohibit mixing meat and dairy, any cheese that carries a kosher certification will not contain animal-derived rennet. This can be a reliable shortcut for finding vegetarian cheese.
• Look for Soft Cheeses: As mentioned, fresh, soft cheeses like paneer, cream cheese, and cottage cheese are typically made without rennet using an acid coagulant.
• Consider Brand Information: Many cheese brands that specifically cater to vegetarians will prominently feature a "Vegetarian" or a "V-Label" logo on their packaging. A quick check of a brand's website can also clarify their rennet source policies.

The Ethical and Practical Differences: Animal vs. Microbial Rennet

Feature	Animal Rennet	Microbial Rennet	Fermentation-Produced Chymosin (FPC)
Source	Stomach lining of young ruminants (e.g., calves)	Specific fungi or mold	Genetically engineered microorganisms (e.g., yeast)
Availability	Dependent on veal/lamb industry; limited supply	Abundant; fermented in large quantities	Abundant; produced in large quantities
Cost	Generally higher; supply can be inconsistent	Often more cost-effective	Highly cost-effective
Flavor Impact	Often preferred for complex flavors in aged cheeses	Modern versions are neutral; older versions could be bitter	Chemically identical to animal chymosin; minimal flavor impact
Ethical Considerations	Requires animal slaughter; not vegetarian	No animal involvement; vegetarian-friendly	No animal involvement; vegetarian-friendly (some may object to GMO source)
Traditional Use	Essential for many Protected Designation of Origin (PDO) cheeses	Modern innovation	Modern innovation

Cheeses to Approach with Caution (or Avoid)

Traditional, Old-World cheeses are the most likely to contain animal rennet due to Protected Designation of Origin (PDO) regulations that mandate its use to preserve historical methods. Some well-known examples include:

• Parmigiano-Reggiano: The traditional recipe legally requires calf rennet. Vegetarian parmesan alternatives exist but are labeled differently (e.g., "Italian hard cheese").
• Pecorino Romano: Traditionally made with lamb rennet.
• Manchego: Genuine Manchego from Spain uses animal rennet.
• Gorgonzola: The traditional Italian version uses animal rennet.
• Gruyère: Authentic Swiss Gruyère is made with animal rennet.

Conclusion: Making Informed Cheese Choices

In conclusion, the simple answer to the question "Why can't vegetarians eat cheese?" is that some cheeses are made using rennet derived from the stomachs of slaughtered animals, a practice incompatible with a vegetarian diet. However, this issue does not apply to all cheese. The rise of modern microbial and plant-based rennets has expanded the market for truly vegetarian-friendly cheese. By carefully reading labels, looking for clear vegetarian or kosher markings, and being aware of which traditional cheeses typically contain animal rennet, vegetarians can navigate the cheese aisle with confidence and enjoy a wide variety of delicious options that align with their dietary principles. Staying informed is the key to making ethical choices without compromising on flavor.

What is Rennet? (External Link)

Learn more about rennet and its role in cheesemaking.

The Difference in Rennet Sources: A Detailed Comparison

Aspect	Traditional Animal Rennet	Modern Microbial Rennet
Source	Abomasum (stomach) of young ruminant animals, typically calves.	Enzymes extracted from the fermentation of specific fungi like Rhizomucor miehei.
Ethical Implication	Byproduct of the meat industry, necessitating the slaughter of the animal.	No animal involvement, making it suitable for vegetarian and kosher diets.
Availability	Limited by the supply of young ruminant animals for meat production.	Easily produced in large, consistent quantities through industrial fermentation.
Flavor Profile	Some argue it produces a more complex, specific flavor, particularly in aged cheeses.	Modern versions are largely neutral, with earlier variants sometimes causing bitterness in aged cheese.
Usage in Industry	Primarily used in traditional and protected designation cheeses.	Dominant type used in mass-produced and many commercial cheeses today.

Conclusion

The confusion surrounding why some vegetarians can't eat cheese is primarily due to a lack of awareness about the ingredients used in traditional cheesemaking. For centuries, rennet from animal stomachs has been a staple for coagulating milk. However, modern technology has provided ethical, animal-free alternatives like microbial rennet and FPC, which are now widely used. While discerning the rennet source requires careful label reading, knowledge empowers vegetarians to make informed decisions. The availability of vegetarian-friendly cheeses is widespread, and knowing which types to check ensures that ethical dietary choices can coexist with the enjoyment of cheese.

Frequently Asked Questions

Is all cheese non-vegetarian?

No, not all cheese is non-vegetarian. Many cheeses are made using microbial or plant-based rennet, which are animal-free alternatives to traditional animal rennet.

What is animal rennet?

Animal rennet is an enzyme complex, primarily containing chymosin, extracted from the stomach lining of young, unweaned ruminant animals like calves. It is used to coagulate milk and is a byproduct of the meat industry.

How can I tell if a cheese is vegetarian?

To identify vegetarian cheese, look for labels indicating 'microbial enzymes,' 'vegetarian rennet,' or a kosher certification symbol. If only 'enzymes' is listed, it may contain animal rennet.

Are all soft cheeses vegetarian?

Many soft cheeses like paneer, ricotta, and cottage cheese are vegetarian because they use acid (like lemon juice) rather than rennet to curdle the milk. However, always check the label to be certain.

Is parmesan cheese vegetarian?

Traditional Parmigiano-Reggiano is never vegetarian because its production is legally required to use animal rennet. However, many grocery stores sell vegetarian "Italian hard cheese" that is made with non-animal rennet.

What is microbial rennet?

Microbial rennet is a vegetarian coagulant produced through the fermentation of microorganisms, typically specific types of fungi. It is widely used in commercial cheesemaking as a replacement for animal rennet.

Does fermentation-produced chymosin (FPC) count as vegetarian?

Yes, FPC is considered vegetarian. It is an animal-free, lab-produced version of the chymosin enzyme found in calf rennet. The final product contains no animal tissue.