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From the sound of its name, it’s probably no surprise that propylene glycol is a synthetic chemical. (It’s actually the main ingredient in antifreeze!) And although its safety is questionable, it’s an incredibly common food additive that the FDA considers “Generally Recognized As Safe” (along with artificial food dyes).
Have you ever seen propylene glycol on a nutrition label and wondered, is it safe? Me too, and here’s what I found out!
What Is Propylene Glycol?
Propylene glycol is derived from petroleum and is a viscous colorless, odorless substance with a sweet taste. Food makers value it for its ability to keep a substance moist, maintain texture, and mix with almost anything (oil, alcohol, and water). Because of these properties and because it is generally recognized as safe, it has become a common food additive in processed or ready-made food items.
Processed food items containing propylene glycol are typically foods that require thickening, emulsifying, or stabilizing properties. These include:
- Salad dressing
- Liquid artificial flavoring
- Ice cream
- Artificial sweetener
- Soft drinks
- Puddings and desserts
- Sauces and dips
Propylene glycol is also often added to body care products, cosmetics, and medications.
Is Propylene Glycol Safe?
The safety of propylene glycol depends on the dose and individual susceptibility. So it is possible that if you are 100% healthy, exposure to small amounts once in a blue moon might be okay.
Unfortunately, when people consume the processed foods listed above, they usually consume a sizable amount on a regular basis, which is definitely not healthy.
Physiological Side Effects of Propylene Glycol
Consumption of propylene glycol has many known effects … here are the biggies.
Acidifies the Blood
Propylene glycol absorbs very quickly in the small intestine with peak levels detected in the blood about an hour after ingestion. It is also quickly eliminated (almost 50% of what is consumed is left after 4 hours).
About 55% of this is metabolized into lactic and pyruvic acids, while the remaining is eliminated by the kidneys (source).
These lactic and pyruvic acids make the blood more acidic. At low doses, the kidneys can immediately re-balance the blood alkalinity. But higher doses of propylene glycol can acidify the blood, injure the kidneys, and cause toxicity. This is why consistent consumption in large amounts is a bad idea.
In a large enough amount it can acidify the blood to the point that it requires emergency medical care. There are a few case reports, including in the New England Journal of Medicine, when patients injected with psychiatric drugs containing propylene glycol were shown to quickly develop acidosis that can cause a coma and kidney failure. Propylene glycol toxicity can also result in similar symptoms to sepsis or severe inflammatory response syndrome (source).
While it is possible to achieve this dosage level by ingesting it, this reaction is typically only reported when it is administered at a very high dose of over ~2 grams (source).
Contributes to Leaky Cells and Leaky Gut
Like soap, propylene glycol is a surfactant, which means it can break the barrier between fat and water. Our cell membranes are made with thin layers of fat molecules, which can be easily disrupted by surfactants like propylene glycol.
Pharmaceutical companies capitalize on this property by mixing or chemically binding drug molecules to propylene glycol to increase the drug absorption rate (source). This is the case for both drugs that are taken orally and topically.
Cells exposed to propylene glycol become more permeable to other molecules (source). (This is why the safety of e-cigarettes containing propylene glycol together with nicotine and cancer-causing substances is very questionable).
Currently, there is no study that directly tests whether propylene glycol causes leaky gut and the inflammatory health problems caused by the leaky gut. However, in a test tube study, propylene glycol even at low concentration destroyed some gut cells (source).
Those who struggle with leaky gut, autoimmune diseases, or digestive issues, may want to consider avoiding propylene glycol for these reasons.
Increases Risks of Childhood Allergies & Asthma
And if that’s not enough, it may affect our kids as well.
As a volatile organic compound (VOC) emitted from building materials, furniture, paint, carpet and the like, propylene glycol can aggravate the immune system. In a study evaluating the effects of propylene glycol and glycol ether vapors in the air on preschool children’s health, the authors found that the presence of such chemicals in a child’s bedroom air is associated with:
- 1.5-fold increased risks of asthma
- 2.8-fold increased risks of allergic rhinitis (hay fever)
- 1.6-fold increased risks of eczema (source)
A good air purifier can help remove airborne chemicals and is a great idea in any sleeping space.
Irritates the Skin
Propylene glycol has been reported as a skin irritant that can cause dermatitis, an eczema-like rash (source). When added to skin, body care, and cosmetic products, it can really aggravate skin problems. (Ironically, it is often an ingredient in topical medications to treat these skin conditions! How does that make sense?!)
When to Avoid Propylene Glycol
Some people are more sensitive to the side effects of propylene glycol than others. Those who are generally cautioned to avoid it are:
- People with liver or kidney problems, because the liver and kidneys are responsible for eliminating propylene glycol and its byproducts
- Pregnant women, babies, and infants as they have reduced ability to handle these types of ingredients (source)
- People with inflammatory health problems because it can irritate cells and cause leaky gut
- People with digestive problems because it will further irritate the gut cells
Fortunately, it is possible to avoid and/or reduce your exposure to as much as possible.
How to Avoid Propylene Glycol
Unfortunately, this additive is in a lot of common products, so it takes some diligence to avoid it! A few tips:
Avoid Processed Foods
The best way to avoid foods dangerous ingredients such as propylene glycol is to eat home-cooked meals the majority of the time. Fake ingredients are not necessary to make food delicious. It is possible to replace the effects of these types of additives with other, natural ingredients, such as gluten-free starch or gelatin as a thickener or stabilizer.
Read Labels and Buy from Trustworthy Brands
Always check the labels of your food ingredients and other household products for propylene glycol and its synonym, propane-1,2-diol.
I like to use brands that never put such dangerous ingredients in their products, like Primal Kitchen for mayonnaise for sauces and dressings.
Check Your Skincare, Body Care, and Home Care Products
Propylene glycol is everywhere in conventional products that people put on their skin every single day. Not only that, these skin products often contain other toxic chemicals that will be more readily absorbed through your skin because it makes your skin more permeable.
Instead, rely on organic products or make your own beauty products instead.
Use Air and Water Purifiers
Despite best efforts to avoid propylene glycol in foods and other products, exposure is still possible in the air or water in your home. Good ventilation (including opening windows to air the house out), a good air purifier in sleeping rooms, and a water filter for drinking and shower water are important.
Have you ever had a reaction to propylene glycol? Which food additives do you say “no” to for your family? Please share with me in the comments!