The Good, The Bad and the Downright Ugly of Cheese

Written by Cyndi

Cyndi is about educating. Her greatest love is to teach, both in the public arena and within the large corporate food companies, to enable everyone to make better choices so they too can enjoy greater health throughout their lives. Considered one of the world's foremost experts in Nutrition, Cyndi brings over 40 years experience, research and knowledge.

April 28, 2015

Last week I was on ABC radio and I was asked to talk about cheese, so I thought the blog this week could be about cheese and more specifically one ingredient in cheese – rennet.

Cheese has a long history in our diet. Traditionally, it is a fermented food with the main ingredients being milk, culture, rennet and salt and for most soft white cheeses like feta and labna, there are only three ingredients: milk, culture and salt.

A mesophilic culture is used for cheeses like colby and edam whereas for mozzarella and parmesan are a more heat resistance culture is used – thermophilic.

If the cheese is salted then unless it indicates a non-refined salt then you can assume that the salt has been refined and could contain anticaking agents and bleaching agents.

Let’s look now at Rennet.


Traditional rennet comes from the lining of the fourth stomach of young calves, goats or lamb; this compound is mainly made from chymosin which is a protease (breaks down protein, more specifically casein). In a calf’s stomach these enzymes curdle the milk allowing a longer residence in the bowel of the young animal and therefore better absorption. In cheese making it is used as a coagulant to separate the curds from the whey.

Modern rennet in cheese can come from another four sources.

Some labels will read simply ‘rennet’. Others say enzymes, vegetarian friendly coagulant, vegetarian rennet, microbial enzymes, vegetable rennet or non-animal rennet. Occasionally ‘chymosin’ is used and sometimes ‘rennet free’ (on a hard cheese!).

Vegetable Rennet
True vegetable rennet comes from plants, which produce certain enzymes that have coagulating properties. Plants include cardoon thistle, fig tree bark or nettles. These are “real” vegetable rennets. However, they often also have undesirable effects on cheese flavor (bitterness) and are a little more unpredictable when used in cheeses not traditionally made with vegetable rennet. Still, some traditional Portuguese cheeses are still made with vegetable rennet as are cheeses in other countries where killing a calf would not be allowed or economically wise. In Australia, commercially produced vegetable rennet is hard, if not impossible, to source.

A more accessible type of vegetable rennet is produced using a bacteria fermented on a plant extract to make chymosin. Most manufacturers who sell this product to commercial cheese makers, as well as people who make their own cheese, add salt to this enzyme and a preservative, usually sodium benzoate (211), a dubious preservative at best. It is known as ‘Chy-max plus’ but will be seen in the ingredient panel as a non-animal rennet or vegetable rennet.

Microbial Rennet
Microbial rennet is a term used to describe a coagulating agent produced by a specific type of mold, fungus or yeast organism grown and fermented in a lab setting. This coagulant is considered vegetarian friendly, as the enzyme produced by the organism is not derived from an animal. While this type of rennet is appropriate for vegetarians, cheese makers agree that cheeses made with this type of microbial rennet tend to result in a bitter flavour profile, especially when the cheese is aged. This coagulant is less expensive than animal rennet, but true microbial rennet is harder to source.  It has been replaced by FPC Rennet.

FPC-Fermentation Produced Chymosin Rennet
This is fairly new type of microbial rennet (1990). This version of microbial rennet is made by taking the rennin-producing gene out of the animal cell’s DNA string (calf, goat or lamb) and then inserting it into the bacteria, yeast or mold host cell’s DNA string (sounds very natural).

Once inserted, the newly placed gene initiates the production of the chymosin enzyme within the host. The host culture is then cultivated and fermented. The result? An inexpensive harvest of real chymosin enzymes. This is seen to be an improvement on the original microbial rennet as it is real chymosin and not a mold or yeast based substitute. Moreover, it can be more economically produced in unlimited supply and addresses some of the concerns with pure microbial rennet regarding the bitter flavor in aged cheeses.

The procedure itself has been around for some time and is similar to the procedure used to make many vaccines.  But, there is more to consider.

FPC rennet is a GMO product. And, according to the culture companies (DMO, Danone, CHR Hansen) 90% of all cheeses produced in countries where there are no rules around GMO are made with FPC rennet.

However, ingredient labels do not distinguish between this type of microbial rennet or the original non-GMO based type. And the fact that use of FPC type microbial rennet is not labeled a GMO product leaves those who oppose the use of GMOs in the dark when it comes to choosing their cheeses.

In addition, further confusion and debate arises over the general differences between GMO products versus “genetically engineered” products as the latter elicits deeper concerns from those opposed to this type of science. While FPC rennet is GMO, it is not a genetically engineered product, technically speaking, because the DNA taken from the animal cell and inserted into the DNA string of a bacterium or mold is not changed.

Genetically engineered foods actually goes as far as to modify the specific gene responsible for a particular function in order to improve its function.  In other words, it takes messing with genes to another, deeper level.  A great analogy is: it’s like playing with the shape of the lego block itself, not just with the order of the lego blocks.

In the end, what this means is that most cheese is made from vegetarian friendly but still animal originated, GMO derived FPC rennet. While use of this type of rennet is banned in GMO-free European countries, it doesn’t mean the cheese we buy from those countries are necessarily FPC free. To quote one Danish expert:

“We can’t use FPC rennet in Denmark for our own domestic cheese or cheese made for other European countries which have banned its use. We only use it for cheese we export to countries that do not have strict guidelines on GMO.”

Why? Because, again, it is a cheaper and more consistently available form of rennet.

Citric Acid or Vinegar
Finally, some cheeses like ricotta are coagulated using simple lemon juice or vinegar. However, this coagulant is mostly used when making a heat precipitated curd. These coagulants are decidedly vegetarian. But this coagulant has a very limited use due to its limitations and noticeable taste profile.

If citric acid is used then it’s important to know that in commercial settings citric acid is usually made from a GMO black mold as opposed to being extracted from citrus fruit.

To eat or not to eat
I often get asked if cheese should be part of a healthy diet – and my answer is, it depends on the individual. For some people, cheese is ok – but others may not be able to tolerate cheese or other dairy products if they are lactose intolerant. It’s important to get to know what foods suit your body as for some people, dairy is a food to avoid as it is an inflammatory food for their body. The best way to determine this is through an loss diet – such as the Hunter Gatherer Elimination Protocol.

All cheeses are not the same
My advice with cheese is the same as for many other products – buy good quality, organic and biodynamic if you can, and always choose food in its purest form. Avoid highly refined cheese like Kraft singles, always read the ingredient labels and look out for additives and bogus claims (which I’ve covered in a previous blog – Bogus Health Claim on Kraft Cheese and Cream Cheese).

I eat all types of cheese as long as they meet these requirements, and I especially love soft cheeses – like brie, camembert, labna, feta, soft goats, sheep and camel cheeses which are all becoming more readily available.

How much is too much?
I recommend that cheese is treated like a condiment rather than something you would have with every meal. It is an individual choice how much cheese you eat. Listen to your body and look for the signs and symptoms so you get to know if your body can tolerate cheese and how much.

Healthy recipes with cheese
The Changing Habits website features a broad range of print-friendly recipes that include quality cheese, including Cauliflower Crust Pizza, Vegetable Lasagne
Roast Pumpkin, Avocado and Fetta Salad and Olive and Fetta Herb Muffins.

The wrap: know your rennet
To conclude, it is important to know your rennet. And it is worthwhile to ask your cheese makers to be clear about what type of rennet they use and why. The rennet a cheese maker chooses to use results in making difficult trade-offs between three priorities: taste, texture and politics.

For that reason, I visit my local cheese makers so I can ask them the question. The problem is that most don’t look at the specification sheets of their product, which they should always receive with any product from another company, therefore they may not know.

Knowledge of rennet enables us to make a better choice. I know it’s but a small part of cheese but when you consider that many of our foods are manipulated it’s good to be in the know rather than in the dark about the ingredients we are choosing to eat.

Thank you to for your wonderful research and information, some of the content has been extracted from this article.

Happy Changing Habits,


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  1. Tamara

    I really want to make my own cheese from raw goat and cow milk. I think I would like to keep it as simple as possible. What recipe would you recommend? I try to live organic and I am not a vegetarian. I have looked at a lot of recipes and think I will start with ricotta, feta and possibly mozzarella. Do i have to use rennet and if so do you know a quality organic source?
    Thank you!

    • Jordan-Changing Habits Nutritionist

      Hi Tamara, I wish we had a recipe for you, but as of this stage we don’t. Perhaps you could have a look at Sally Fallon’s Nourishing Traditions to see if there is a suitable recipe there so you can begin your cheese making!
      Kind regards, Jordan 🙂

      • Cassie

        If you are interested in cheese making I highly recommend the cheese making workshop in Coffs Harbour. My husband and I did one a few weeks ago, it was great! I believe they do various workshops in other cities at times.

  2. Anna

    So in conclusion..I enjoy cheese..but which are the healthiest to eat..I am more vegetarian but do not eat GMO is any rennet healthy? Still would like better direction in this area..which cheeses should be eaten if you have an autoimmune illness..any brands for recommendations? Thanx

    • Tessa

      Hi Anna,

      This is a really hard question to answer as even when you call the dairy to find out what rennet they use in their cheese they are none the wiser.

      There are three types of rennet.
      The original from the stomach of a ruminant
      A genetically modified microbe making the rennet
      And now they have a genetically modified enzyme.

      Here is a link that goes into the pros and cons


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