Sodium benzoate is a preservative added to some sodas, packaged foods, and personal care products to prolong shelf life.

Some people claim that this man-made additive is harmless, while others link it to cancer and other health problems.

This article provides a detailed overview of sodium benzoate, including its uses and possible safety concerns.

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Sodium benzoate is best known as a preservative used in processed foods and beverages to extend shelf life, though it has several other uses.

It’s an odorless, crystalline powder made by combining benzoic acid and sodium hydroxide. Benzoic acid is a good preservative on its own, and combining it with sodium hydroxide helps it dissolve in products (1).

Sodium benzoate does not occur naturally, but benzoic acid is found in many plants, including cinnamon, cloves, tomatoes, berries, plums, apples, and cranberries (2).

Additionally, certain bacteria produce benzoic acid when fermenting dairy products like yogurt (1, 3).

Summary Sodium benzoate is a man-made compound. It’s best known as a food preservative, though it has several other uses.

Aside from its use in processed foods and beverages, sodium benzoate is also added to some medicines, cosmetics, personal care products, and industrial products.

Here’s a closer look at its many functions.

Foods and Beverages

Sodium benzoate is the first preservative the FDA allowed in foods and still a widely used food additive. It’s classified as Generally Recognized As Safe (GRAS), meaning that experts consider it safe when used as intended (1, 4).

It’s approved internationally as a food additive and is assigned the identifying number 211. For example, it’s listed as E211 in European food products (5).

Sodium benzoate inhibits the growth of potentially harmful bacteria, mold, and other microbes in food, thus deterring spoilage. It’s particularly effective in acidic foods (6).

Therefore, it’s commonly used in foods, such as soda, bottled lemon juice, pickles, jelly, salad dressing, soy sauce, and other condiments.

Medications

Sodium benzoate is used as a preservative in some over-the-counter and prescription medications, particularly in liquid medicines like cough syrup.

Additionally, it can be a lubricant in pill manufacturing and makes tablets transparent and smooth, helping them break down rapidly after you swallow them (1).

Lastly, larger amounts of sodium benzoate may be prescribed to treat elevated blood levels of ammonia. Ammonia is a byproduct of protein breakdown, and blood levels may become dangerously high in certain medical conditions (2).

Other Uses

Sodium benzoate is commonly used as a preservative in cosmetics and personal care items, such as hair products, baby wipes, toothpaste, and mouthwash (2).

It also has industrial uses. One of its biggest applications is to deter corrosion, such as in coolants for car engines (2, 7).

What’s more, it may be used as a stabilizer in photo processing and to improve the strength of some types of plastic (2).

Summary Sodium benzoate is a versatile chemical with preservative, medicinal, and other functions. It’s used in certain packaged foods, beverages, medicines, cosmetics, as well as personal care and industrial products.

Some people are generally leery of all chemical additives, including sodium benzoate. Preliminary studies raise questions about its safety, but more research is needed.

Converts to a Potential Cancer Agent

A large concern over the use of sodium benzoate is its ability to convert to benzene, a known carcinogen.

Benzene can form in soda and other drinks that contain both sodium benzoate and vitamin C (ascorbic acid) (8).

Notably, diet beverages are more prone to benzene formation, as the sugar in regular sodas and fruit drinks may reduce its formation (9).

Other factors, including exposure to heat and light, as well as longer storage periods, can increase benzene levels (9).

In 2005, 10 out of 200 sodas and other fruit drinks tested by the FDA contained more than 5 parts per billion (ppb) of benzene — which is the limit for safe drinking water set by the US Environmental Protection Agency (EPA) (8).

Particularly, fruit-flavored diet sodas and juice drinks exceeded 5 ppb of benzene. Since then, these ten drinks have either been reformulated to yield acceptable levels or have had sodium benzoate removed entirely.

The FDA has not published more recent product analyses but has stated that the low levels of benzene found in beverages don’t pose a health risk (8).

Still, long-term studies assessing the relationship between regularly consuming low levels of benzene and cancer risk are lacking (9).

Other Potential Health Concerns

Preliminary studies have evaluated other possible risks of sodium benzoate, which include:

  • Inflammation: Animal studies suggest that sodium benzoate can activate inflammatory pathways in the body in direct proportion to the amount consumed. This includes inflammation promoting cancer development (10).
  • Attention Deficit Hyperactivity Disorder (ADHD): A study of college students linked ADHD with higher intake of sodium benzoate in beverages. The additive has also been linked to ADHD in children in some studies (11, 12).
  • Appetite control: In a test-tube study of mouse fat cells, exposure to sodium benzoate decreased the release of leptin, an appetite-suppressing hormone. The decrease was 49–70%, in direct proportion to the exposure (13).
  • Oxidative stress: Test-tube studies suggest that the higher the concentration of sodium benzoate, the more free radicals are created. Free radicals can damage your cells and increase chronic disease risk (14).
  • Allergies: A small percentage of people may experience allergic reactions — such as itching and swelling — after consuming foods or using personal care products that contain sodium benzoate (6, 15, 16).

More research, particularly in people, is needed to confirm these initial findings.

Summary Studies suggest that sodium benzoate may increase your risk of inflammation, oxidative stress, obesity, ADHD, and allergies. It may also convert to benzene, a potential carcinogen, but the low levels found in beverages are deemed safe.

In larger doses, sodium benzoate may help treat certain medical conditions.

The chemical reduces high blood levels of the waste product ammonia, such as in people with liver disease or inherited urea cycle disorders — conditions that limit the excretion of ammonia via urine (17, 18).

Furthermore, scientists have identified ways by which sodium benzoate may have medicinal effects, such as by binding unwanted compounds or affecting the activity of certain enzymes that increase or decrease levels of other compounds (19, 20).

Other potential medicinal uses of sodium benzoate that are being researched include:

  • Schizophrenia: In a six-week study in people with schizophrenia, 1,000 mg of sodium benzoate daily alongside standard drug therapy reduced symptoms by 21% compared to placebo. A similar study also showed a benefit (21, 22).
  • Multiple sclerosis (MS): Animal and test-tube studies suggest that sodium benzoate may slow MS progression. This may include stimulating myelin production, the protective nerve covering damaged in MS (23, 24, 25, 26).
  • Depression: In one six-week case study, a man with major depression given 500 mg of sodium benzoate daily had a 64% improvement in symptoms, and MRI scans showed improved brain structure related to depression (27).
  • Maple syrup urine disease: This inherited disease inhibits the breakdown of certain amino acids, making urine smell like syrup. A study in one toddler found intravenous (IV) sodium benzoate to help in a crisis phase of the disease (28).
  • Panic disorder: When a woman with panic disorder — characterized by anxiety, abdominal pain, chest tightness, and palpitations — took 500 mg of sodium benzoate daily, her panic symptoms were reduced by 61% in six weeks (19).

Despite potential benefits, sodium benzoate can have side effects, including nausea, vomiting, and abdominal pain (2, 18).

Additionally, medicinal doses of sodium benzoate may deplete your body of the amino acid carnitine, which plays a critical role in energy production. This may make it necessary to take a carnitine supplement (29, 30).

For these reasons, sodium benzoate is only given as a prescription medication in carefully controlled doses and with ongoing monitoring.

Summary Sodium benzoate medicine can be used to treat high blood ammonia levels. It is also being studied for potential use in other conditions, including schizophrenia and multiple sclerosis.

The FDA allows up to a 0.1% concentration of sodium benzoate by weight in foods and beverages. If used, it must be included in the ingredient list (31).

Your body doesn’t accumulate sodium benzoate. Rather, you metabolize and excrete it in your urine within 24 hours — which contributes to its safety (31).

The WHO has set the acceptable daily intake (ADI) level for sodium benzoate to 0–2.27 mg per pound (0–5 mg per kg) of body weight. People generally don’t exceed the ADI through a normal diet (2, 32, 33).

Still, some people may be more sensitive to this additive. Consult a doctor for appropriate testing if you suspect you have an allergy to sodium benzoate (2).

As for sodium benzoate in personal care products, the Environmental Working Group ranks the additive at a hazard level of 3 on a scale of 0 to 10 — meaning that overall risk of its use is relatively low (34).

Summary The FDA limits how much sodium benzoate can be added to food and beverages. You are unlikely to experience toxicity based on typical exposure.

Sodium benzoate is deemed safe, and people generally don’t exceed the ADI of 0–2.27 mg per pound (0–5 mg per kg) of body weight, though some individuals may be more sensitive.

This additive has been linked to an increased risk of health issues like inflammation, ADHD, and obesity, but more research is needed.

Remember that some additives lose their Generally Recognized As Safe (GRAS) approval as new studies are completed, so it’s important to continue evaluating its safety and to recognize individual variability how the additive is tolerated.

Regardless, it’s always wise to minimize your intake of processed foods and select personal care products with fewer man-made additives and more natural ingredients.