What to Know About Propylene Glycol in Foods

Medically Reviewed by Zilpah Sheikh, MD on June 21, 2024
Written by Kathryn Whitbourne
7 min read

The foods you buy from grocery stores can contain many ingredients, especially ones with chemical-sounding names, called food additives. Some additives enhance flavor, while others help in food preservation. One common additive is propylene glycol, found in salad dressings and other foods. 

Propylene glycol is also present in many cosmetics, dog food, bath products, and medications. The industrial version is an active ingredient in engine coolants, airplane deicers, enamels, paints, varnishes, and polyurethane cushions.‌

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Propylene glycol is a colorless, nearly odorless, and tasteless thick liquid. It's used in many processed products because it helps them maintain their consistency, moisture, and texture. The chemical is usually made from petroleum, though some companies are now making it from plants like canola and soybean. Propanediol is a substitute for propylene glycol made from corn. ‌

Propylene glycol (PG) has other names, including:

  • Trimethyl glycol
  • Methyl ethyl glycol
  • 1,2-dihydroxypropane
  • 1,2-propanediol‌

The product enters your body if you:

  • Consume foods or medicines containing it
  • Breathe air containing a mist from it
  • Rub it on your body using a cream or cosmetic

It's likely you've been exposed to PG, since it's in so many products. 

 

 

 

 

Propylene glycol has several uses in the food industry and beyond. Because it has almost no flavor or color of its own, it can be added to food without a consumer noticing. The product is used as a:

Thickener: Thickens foods to improve their texture, taste, and "mouth feel"

Emulsifier: Binds ingredients that normally don't mix, like oil and water; often used in low-fat foods

Stabilizer: Stabilizes the emulsion process so the product remains thick. For instance, mayonnaise (made up of oil, water, and other things) might need both an emulsifier and a stabilizer. Although emulsifiers, stabilizers, and thickeners are classified as different products, they're often sold as a combination.

Anticaking agent: Keeps powdered products (like salt, cake mixes, and cocoa) from clumping

Humectant: Keeps foods, like baked goods, moist

Antioxidant: Extends the shelf life of food

Processing aid: Enhances the look of food

Other uses for propylene glycol

  • Creating artificial smoke in firefighting demonstrations or theater shows
  • Creating vapor in e-cigarettes
  • Stabilizing drugs and removing excess moisture from them to increase shelf life
  • Preventing bacterial growth in cosmetics
  • Preventing spoilage during winemaking
  • Controlling temperature while brewing beer
  • Preventing antifreeze from freezing
  • Solvent for paint and plastics

Propylene glycol comes in various grades for use in different applications: 

Food grade. Food-grade PG is found in products like seasonings, soup blends, teas, soft drinks, and baking mixes. It keeps powdered ingredients from caking up, protects them against moisture, and enhances flavor. It's considered safe by the FDA.

USP grade. USP stands for United States Pharmacopeia, a regulatory organization. This means the product is fit to use in food, drugs, and medicines. All drugs sold in U. S. are required to meet USP standards, and some manufacturers include those letters on their drug labels. Propylene glycol USP has a very high purity grade. It's used as a food stabilizer, a moisturizer in skin care cosmetics and shampoos, and a solvent in drug formulas.

Propylene glycol alginate. This is made from brown seaweed and used widely as a thickener, emulsifier, and stabilizer in dairy products, beer foam, and other products. It's considered safe by the FDA. Propylene glycol alginate is a version of PG that can be used in some products that PG can't.

 

 

 

Propylene glycol has many properties that benefit packaged foods. Examples of packaged foods that contain the product include:

  • Seasoning blends
  • Dried soups
  • Salad dressings
  • Baking mixes for cakes, muffins, biscuits, pancakes, etc.
  • Powdered drink mixes
  • Flavored teas
  • Soft drinks
  • Alcoholic beverages
  • Food coloring
  • Flavoring extracts
  • Highly processed snacks
  • Fast foods
  • Flavored popcorn
  • Cake frosting
  • Ice cream flavors
  • Mass-distributed baked desserts
  • Marshmallows
  • Dried coconut shreds
  • Sauces
  • Sour cream
  • Potato salad

People against the use of PG in food argue that its levels in food are beyond what the World Health Organization (WHO) recommends. According to the WHO, the acceptable limit is 25 milligrams of propylene glycol per kilogram of your body weight. In the U.S., the average exposure is about 34 milligrams per kilogram of body weight. One kilogram is 2.2 pounds.

Some people recommend reducing your dietary sources of PG, citing the following potential health risks:‌

Worsened kidney and liver disease symptoms. If you have normal liver and kidney function, your body can easily remove propylene glycol. About 45% of the compound gets out of the body through the kidneys unchanged. The body breaks down the rest into lactic acid. But in large quantities, lactic acid can build up and lead to kidney failure and acidosis. Acidosis means your body can’t remove the acid as fast as it should, leading to toxicity (poisoning). 

If you have kidney or liver disease, the process of getting rid of the compound is slow. The main sign of toxicity is depression of your central nervous system, causing a low heart rate, slow rate of breathing, and loss of consciousness.‌

Allergic reactions. A small number of people are allergic to propylene glycol. The most common signs are skin reactions, dermatitis, and a rash on the face or the whole body.‌

Increased risk of a heart attack. When propylene glycol is injected in high amounts, it leads to a rapid heart rate, heart rhythm problems, or low blood pressure. 

Seizures. There've been reports of infants getting seizures after getting large doses of vitamin D where PG was used to administer the vitamin. It's also happened occasionally in adults getting very large doses of drugs made with PG.

Toxicity from propylene glycol is rare. When it happens, it's because someone consumed an amount of propylene glycol far beyond that found in a typical food product. Often it's due to taking large doses of medicine by injection where PG was used as a solvent for the drug. 

Those at risk of PG toxicity include: 

  • People with kidney or liver disease. You need a healthy liver to break down PG and healthy kidneys to remove it from the body.
  • People with an impaired alcohol dehydrogenase enzyme system. Alcohol dehydrogenase is an enzyme needed to break down propylene glycol in your body. Children under 4 years old and pregnant women usually have low levels of alcohol dehydrogenase. So do people with liver disease and those taking the drugs disulfiram (for treating alcoholism) or metronidazole (an antibiotic).
  • Burn patients who've received many skin treatments containing PG. They're at risk of getting a condition called hyperosmolar metabolic acidosis.
  • People with epilepsy. Seizures are possible with large doses of PG.

Treatment for PG toxicity could include kidney dialysis, to remove the propylene glycol from the body, or fomepizole, a drug used to block alcohol dehydrogenase. This stops the the enzyme from breaking down poisonous levels of PG in your body.

Most processed foods contain at least some propylene glycol. PG normally leaves your body in about 48 hours, so there's no trace of it. It's considered to be a safe chemical and as such is not tested in food. Food-grade PG isn't available for sale to the public in the U.S., so you wouldn't be able to ingest large quantities of it. 

If you're still concerned about PG in your food, you can do the following:

  • Read your labels before buying to see if PG is an ingredient. Propylene glycol may be listed as propylene glycol mono and diester, or E1520 on the label.
  • Eat fewer processed foods, since PG is a part of so many of them. For instance, make your own salad dressings and baking mixes instead of buying them.
  • Eat more whole foods. 

The FDA classifies PG as an additive that is "generally recognized as safe" (GRAS). This may not sound super-positive, but that is typical language used by the FDA when regulating food additives. It's also considered safe by European and Canadian authorities, but with some restrictions in Europe.

Sometimes, people confuse propylene glycol with ethylene glycol. Their chemical structures are similar, and both are used in antifreeze, but they’re not the same. 

In antifreeze, propylene glycol lowers the freezing point of water, which keeps the antifreeze product liquid. It replaces ethylene glycol in antifreeze, an ingredient that did the same thing but was very toxic. Propylene glycol-based antifreeze is considered nontoxic.

A few people are allergic to PG in health and beauty products, such as shampoos, lotions, and shaving creams. You'd know this if the product caused your skin to swell, itch, and become red. Treatment is applying a steroid cream and no longer using the product causing the problem. 

Propylene glycol is a man-made alcohol used in many food products to add texture, taste, and thickness. This versatile additive is also found in medicines, toiletries, and cosmetics. The industrial version is used as a deicer, in antifreeze, and to make artificial smoke, among other things. Although some people have raised concerns, the FDA regards the product as safe, so if you see it as an ingredient on a food label, you shouldn't worry. If you wish to avoid PG, try to buy fewer processed foods and stick to whole foods. 

Why is propylene glycol banned in Europe? 

The chemical is not banned in Europe. The European Food Safety Authority considers PG to be safe. PG is an approved food additive, as well as approved for use in cosmetics and pharmaceutical products. The European Union does require a much lower level of PG in its food than the U.S. does. But this doesn't mean that the level in U.S. food is unsafe.

Does milk have propylene glycol? 

Propylene glycol is often mixed in animal feed given to cows because it decreases occurrence of a disease called ketosis. It also increases milk yield and decreases milk fat percentage. So, it is possible that your milk has PG in it indirectly from use in animal feed. But it's not typically added to milk; any amount in your milk would be extremely small. 

How does propylene glycol work in food preservation? 

When foods come in contact with oxygen, they often start to dry out and break down. Propylene glycol protects foods against these effects and keeps them moist.