Have you seen this online yet, or more likely on some social media page? The first time I saw a comment about store-bought pre-shredded cheese being “toxic” was from a fitness influencer on a social media story. I’m sure the whole neighborhood heard my eye roll. Seeing that made me wonder what they were talking about, so I started looking into this claim because the IG story had no information or evidence to back it.
First, let’s clarify what toxic is. According to Merriam-Webster online Dictionary, “Toxic” has several meanings:
1) containing or being poisonous material, especially when capable of causing death or severe debilitation.
2) exhibiting symptoms of infection or toxicosis
3) extremely harsh, malicious, or harmful
toxic sarcasm
4) relating to or being an asset that has lost so much value that it cannot be sold on the market
Additionally, when considering the term "toxic," it is essential to remember that the dose makes the poison. For example, water is crucial for life. Without water, most living beings die within a few days. At the same time, water toxicity is real, and people die every year from water intoxication. Please let me know if I’ve missed a case of toxic pre-shredded cheese poisoning ever being documented.
So, why are people claiming that shredded cheese is toxic? There are several reasons people think pre-shredded cheese is not a good product. Using the term “toxic” is nothing more than sensationalism to get likes, follows, or people reading their articles, not because they have any evidence of actual reported cases of pre-shredded cheese toxicity.
One argument made for why shredded cheese is “toxic” or not good for you is as simple as the excessive use of ingredients. Most arguments are based on health concerns of those additional ingredients. The additional ingredients in shredded cheese serve several purposes, including reducing the likelihood of mold, yeast, and fungal growth.
What are the additional ingredients, and why do people avoid them?
Cellulose/potato starch – Adding cellulose or potato starch to pre-shredded cheese keeps it from sticking together and absorbs moisture in the bag. If you’ve pre-shredded a block of cheese and stuck it in a bag for future use, it tends to stick together and is not as easy to use in the shredded form. It also will go bad more quickly due to the extra surface area exposed to air and potential moisture buildup, which can cause mold, fungus, and yeast to form. There is no evidence or research that cellulose or potato starch negatively impacts human health unless you are sensitive to these ingredients. Cellulose is added to several food products to increase insoluble fiber.
Adding cellulose and potato starch to pre-shredded cheese has a drawback. It negatively impacts some culinary uses, such as sauces. The powdery substance of the added cellulose or potato starch will change the sauce's texture, which, while not ideal, is certainly not toxic to physical human health.
Calcium Sulfate – One of the arguments I read about why this anti-caking ingredient is sometimes used in shredded cheese is because “it’s used to make ground cement and making tiles. Do you really want that in your cheese?” The appeal to emotions here is strong but misplaced. Calcium sulfate is used in insignificant amounts in a wide variety of foods. The FDA and the European Food Safety Authority have classified it as a GRAS (Generally Recognized as Safe) substance. Again, the dose makes the poison. Just because a small quantity of an ingredient happens to be used for non-food purposes does not inherently make the food toxic, which should be avoided. Several mineral compounds found in food can also be used for non-food manufacturing. Iron, zinc, and copper all have functions in the human body and manufacturing.
Ferrous Oxide has several industrial uses, including iron ore, cleaning jewelry, and cosmetics. It is also used in the food industry to fortify food with iron. Zinc oxide is used in sunscreens and to prevent diaper rash. Zinc Sulfate has been used in treatment to prevent moss on roofs and fertilizers, amongst other non-food uses. Both are considered safe for human consumption as a zinc supplement or food fortification.
Natamycin – I suspect this is the ingredient that people are referring to when they claim shredded cheese is toxic.
Natamycin is an antifungal added to shredded cheese and many other foods to prevent mold, yeast, and fungus from forming.
The least compelling argument is that natamycin is produced by fermenting naturally found bacteria in soil, and who wants to eat something from a dirt bug in the soil? However, all food comes from the soil in one way or another, so avoiding an ingredient because it comes from the soil is not a valid argument.
Other arguments for avoiding Natamycin or calling it toxic are because there are several medical applications for treating yeast and fungal infections, including a treatment for an eye fungus. Again, the appeal to emotion about why we would eat that. The amount added to shredded cheese is minimal compared to the dose used for medical treatments. Using Natamycin is to prevent mold and fungus from forming. Consuming mold or fungus from cheese can harm humans in a high enough dose. It also extends the shelf life since shredded cheese has more surface area exposure to air, which increases the risk of mold and fungus formation.
What does the research say?
Research studies are being used to support claims that Natamycin is toxic, to justify why it is on some individuals' personal avoid list or to explain why Whole Foods included it on its list of unacceptable food ingredients. However, the use of these studies has significant limitations and flaws.
The most egregious argument I saw was a medical doctor's website that linked three studies to justify adding Natamycin to their list of foods to avoid. The first one was a study from 2009 claiming that Natamycin causes DNA damage. The study was not a human trial and involved treating human cells in various concentrations of Natamycin solution for 24-48 hours. When we eat food, however, our cells do not sit in a high concentration of Natamycin for 24-48 hours. Not surprisingly, the MD, who is biased towards not consuming Natamycin, did not include a link to a study from 2014 that used the actual ingestion of Natamycin to determine that there is a negligible or low toxicity effect from its ingestion.
Another study on mice, used by the MD, was retracted and corrected by the authors due to fundamental scientific errors. The MD linked the summary of the article, which only had a name correction. Following the link to the Full Article, it clearly states the author has retracted the study.
In a final study, the same MD linked, he implied in a heading that Natamycin may cause digestion problems by interfering with the bacteria in our bowels. Natamycin does not act against bacteria, though. It is one of the advantages of using it since it does not contribute to the overuse of antibiotics that are linked to antimicrobial resistance. The study link on the MD website takes you to the summary of an article called “The Gut Flora as the Forgotten Organ”. There is no mention of Natamycin in the summary available through the link on the MD website, nor is it mentioned, or any antimicrobial, in the full text.
Finally, the U.S. Food and Drug Administration is not the only authority that has approved the use of Natamycin as a food additive. Canada Health, the European Food Safety Authority (EFSA), the Joint FAO/WHO Expert Committee on Food Additives (JECFA), and other authorities have also approved the use of Natamycin in food. I’ve heard more than once that people are concerned that the United States allows food additives to be banned in other countries. Most countries are on board with using Natamycin as a food additive.
Some individuals are sensitive to ingesting Natamycin, so they would be better off avoiding pre-shredded cheese treated with Natamycin. However, just because some people are sensitive to an ingredient does not necessarily equate to toxicity.
What frustrates me as a nutrition professional is when people on social media and blogs spread misinformation to influence others. For example, an Instagram Story with a fitness professional passive-aggressively shaming others for using store-purchased pre-shredded cheese.
There is no reason to shame people for being busy and choosing a quicker alternative. If you decide to avoid an ingredient or are sensitive to it, it does not mean everyone should avoid it. Using social media status or the authority of your profession, such as an MD, to try to shame and fear people into avoiding certain foods is the opposite of helping. Our role is to address the real health issues of food, such as the saturated fat content of cheese, and keep the content evidence-based with a body of research behind it. A medical professional's role should not be fearmongering and should not use selective research to support a bias.
The only other argument I’ve seen against using shredded cheese is the cost. The cost per pound of shredded cheese and block cheese is typically the same at the stores I shop at. Shredded cheese is often less expensive per pound than block cheese. When it saves you time shredding and cleaning additional kitchen utensils, there is an extra cost savings of your time.
Shredded cheese can have several advantages over block cheese. Saving time with meal preparation is a huge bonus for many hard-working individuals with limited time. Using shredded cheese also saves cleaning up a cheese shredder. Honestly, I do not enjoy cleaning food shredders, especially after using them to shred cheese. If you make a cheese sauce from scratch, you’re better off using block cheese. You can cut the cheese into small blocks rather than shredding them to save time and prevent cleaning an extra utensil. Cook time will increase for the blocks to melt.
So, if you like the convenience of packaged, pre-shredded cheese, you can feel comfortable knowing it is not toxic. There has never been a documented case of toxic shredded cheese poisoning. If you prefer shredding your cheese from the block, go for it! You will burn extra calories by shredding the cheese and prefer the taste. If you shred a softer cheese, like mozzarella, you can stick the block or ball in the freezer for 20-30 minutes to make shredding easier.
Make the best choice for yourself and your household, but let’s not worry about whether others opt for block or pre-shredded cheese.
If you're tired of all the nutrition bullshit out there and want help making the best choices for the healthiest version of you, schedule a complimentary nutrition consultation with HealthyU Nutrition's Registered Dietitian Nutritionist, Cary Cuevas. Oregon residents only.