Propylene glycol is a common food and cosmetics ingredient deemed generally safe by US and European food authorities. However, its use in antifreeze has caused some health concerns.
This article investigates what propylene glycol is, why it is used, and whether it is dangerous to your health.
Propylene glycol is a synthetic food additive that belongs to the same chemical group as alcohol.
It is a colorless, odorless, slightly syrupy liquid that is a bit thicker than water. It has practically no taste.
Additionally, it can dissolve some substances better than water and is also good at retaining moisture. This makes it very useful as a food additive, so it can be found in a wide variety of processed foods and drinks.
Other names it is known by include:
- 1,2-propanediol
- 1,2-dihydroxypropane
- Methyl ethyl glycol
- Trimethyl glycol
Propylene glycol is sometimes confused with ethylene glycol, as both have been used in antifreeze due to their low freezing points. However, these are not the same substance.
Ethylene glycol is highly toxic to humans and is not used in food products.
Propylene glycol is commonly used as an additive to aid in the processing of foods and improve their texture, flavor, appearance and shelf life.
In foods, propylene glycol may be used in the following ways:
- Anti-caking agent: It helps prevent food components from sticking to one another and forming clumps, such as in dried soups or grated cheese.
- Antioxidant: It extends the shelf life of foods by protecting them against deterioration caused by oxygen.
- Carrier: It dissolves other food additives or nutrients to be used in processing, such as colors, flavors or antioxidants.
- Dough strengthener: It modifies the starches and gluten in dough to make it more stable.
- Emulsifier: It prevents food ingredients from separating, such as oil and vinegar in salad dressing.
- Moisture preserver: It helps foods maintain a stable level of moisture and stops them from drying out. Examples include marshmallows, coconut flakes and nuts.
- Processing aid: It is used to enhance the appeal or the use of a food, for example, to make a liquid clearer.
- Stabilizer and thickener: It can be used to hold food components together or thicken them during and after processing.
- Texturizer: It can change the appearance or mouthfeel of a food.
Propylene glycol is commonly found in many packaged foods, such as drink mixes, dressings, dried soups, cake mix, soft drinks, popcorn, food coloring, fast foods, bread and dairy products.
It is also used in injectable medications, like lorazepam, and in some creams and ointments that are applied to the skin, such as corticosteroids.
Due to its chemical properties, it is also found in a wide variety of hygiene and cosmetic products. Additionally, it is used in industrial products like paint, antifreeze, artificial smoke and e-cigarettes.
Propylene glycol is “generally recognized as safe” (GRAS) by the
In the US, it can be used as a direct and indirect food additive. In Europe, it is only allowed to be used in food as a solvent for colors, emulsifiers, antioxidants and enzymes.
The World Health Organization recommends a maximum intake of 11.4 mg of propylene glycol per pound of body weight (25 mg/kg) per day. The estimated exposure to propylene glycol through foods in the US is 14-34 mg/kg per day.
There is only one documented case of propylene glycol toxicity caused by food.
A man drank very large amounts of cinnamon whiskey containing propylene glycol and was found unconscious. While his symptoms were also due to the alcohol, some could be attributed to the propylene glycol.
Overall, apart from people with allergies and one case of excessive consumption, there have been no other reported cases of negative or toxic effects of propylene glycol in foods.
However, as current intakes are estimated to be above the recommended level, it may be wise to reduce dietary sources where you can, especially as the primary sources are highly processed foods.
There is a lot of conflicting information about the dangers of propylene glycol.
Some websites state it is safe, while others claim it causes heart attacks, kidney and liver failure and brain problems.
How toxic Is propylene glycol?
The toxicity of propylene glycol is very low. It has not been found to cause cancer, damage genes or interfere with fertility or reproduction. Moreover, there are no reported deaths on record.
After ingesting a food containing propylene glycol, about 45% of it will be excreted by the kidneys unchanged. The rest is broken down in the body into lactic acid.
When consumed in toxic quantities, the buildup of lactic acid can lead to acidosis and organ failure. Acidosis occurs when the body cannot get rid of the acid fast enough. It begins to build up in the blood, which interferes with proper functioning.
Cases of poisoning may be treated with hemodialysis to remove the substance from the blood or by removing the drug or substance that contains propylene glycol.
However, toxicity is very rare. Most cases resulted from the use of
Dangers for people with kidney or liver disease
In adults with normal liver and kidney function, propylene glycol is broken down and removed from the blood fairly quickly.
On the other hand, in people with kidney disease or liver disease, this process may not be as efficient. This can lead to a buildup of propylene glycol and lactic acid in the bloodstream, causing symptoms of toxicity.
Additionally, because there is no maximum dose limit for propylene glycol used in drugs, it is possible to receive very high doses in some circumstances.
In an
Critically ill patients often have impaired kidney or liver function and may also have an increased risk from prolonged or high-dose drug treatments.
For example, in a
For people with kidney and liver disease, drug alternatives without propylene glycol may be used if needed. There is no evidence that dietary amounts are cause for concern.
Dangers for infants and pregnant women
Pregnant women, children and infants under four years of age have lower levels of an enzyme known as alcohol dehydrogenase. This enzyme is essential for the breakdown of propylene glycol.
Therefore, these groups may be at risk of developing toxicity if they are exposed to large amounts through medication.
Infants are at particular risk. They take longer to remove propylene glycol from their bodies and may be particularly sensitive to the effects on the central nervous system.
However, a
While these populations may be at increased risk of toxicity in the case of very high exposure from medication, there is no research indicating any harm from the amounts found in the diet.
Risk of heart attack
Some websites claim that propylene glycol increases the risk of heart disease and heart attacks.
It is true that when propylene glycol is injected in high amounts or too quickly, a drop in blood pressure and heart rhythm problems can occur.
The amount of propylene glycol found in a normal diet is not associated with any heart problems in children or adults.
Neurological symptoms
There have been some older reports of propylene glycol causing brain-related symptoms.
In a case in 1988, a woman with epilepsy developed repetitive convulsions and stupor due to propylene glycol poisoning from an unknown source.
Additionally, in a
While these symptoms may sound scary, it should be emphasized that many different medications and substances can cause similar symptoms when ingested or given in quantities that cause toxicity.
There have been no reports of neurological changes due to propylene glycol in foods.
Skin and allergic reactions
The American Contact Dermatitis Society has named propylene glycol as the
The most common skin reaction, or dermatitis, is the development of a rash on the face or in a generalized scattered pattern over the body.
Systemic dermatitis has been reported after
In addition, propylene glycol can cause irritant contact dermatitis. In this case, a rash may develop in sensitive people when their skin comes into contact with products that contain it, such as shampoo or moisturizer.
People who already have skin conditions or sensitive skin are at particular risk of contact allergy to this additive.
For people with allergic dermatitis, it is best to avoid all sources of propylene glycol. For contact dermatitis, avoid products containing it that come into contact with the skin.
While propylene glycol is generally considered safe, you may still choose to avoid it if you are allergic or you simply want to reduce your intake.
It is found in many different food products and can be identified by checking the ingredients list. The names it may be listed under include:
- Propylene glycol
- Propylene glycol mono and diester
- E1520 or 1520
Common foods include soft drinks, marinades and dressings, cake mix, frosting, popcorn, food coloring, fast foods, bread and dairy products.
Unfortunately, if propylene glycol is used as a carrier or solvent for another additive, such as flavor or color instead of a direct ingredient, it may not be listed on the food label.
However, the majority of foods containing it are highly processed junk foods. By consuming a fresh, healthy, whole foods diet, you can avoid most sources without too much trouble.
You can also check the labels of cosmetic products, though avoiding it may be difficult.
If you have an allergy to propylene glycol, it is important to let your doctor or pharmacist know about it before taking certain medications. An alternative can usually be found.
Propylene glycol is a useful chemical found in a wide variety of products across the food, drug, cosmetic and manufacturing industries.
While there are cases of toxicity from very high doses of medication, it is overall considered a very low-toxicity substance.
A small percentage of people are allergic to propylene glycol and may need to avoid products containing it.
Yet for most people, the amounts regularly found in food products are considered safe.
Keep in mind that most of the foods containing propylene glycol are highly processed junk foods. A fresh, whole foods diet will naturally contain lower amounts of this additive.
