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What Is Potassium Benzoate?

author image Chad Bjorklund
Chris Bjorklund has been writing professionally since 2004 and has been primarily featured in peer-reviewed scientific journals such as "Nucleic Acids Research" and "Biochemistry." He has also been anonymously published as a content freelancer for several websites. He completed his doctoral degree in biochemistry at Washington State University in 2006.

Potassium benzoate is a chemical preservative that is commonly added to some foods and drinks, but most notably soft drinks. Potassium benzoate is an effective preservative because it blocks the growth of some bacteria, yeast and mold. When dissolved in liquid, it separates into its two parts, the electrolyte potassium and the benzoate salt. Potassium is extremely important for several biological processes including the muscle contraction associated with the beat of your heart.

Potassium Function

Potassium is an essential mineral that is required by all of your cells, tissues and organs for proper function. Along with calcium, sodium and magnesium, potassium acts as an electrolyte because it helps propagate electrical signals and pulses throughout your nervous system. In addition to its importance for maintaining proper heart rhythm, potassium is also needed for smooth muscle contraction, which is necessary for the health and function of your digestive system.


Potassium deficiency is characterized as hypokalemia. A well-balanced diet typically supplies enough potassium, but certain prescription medications, like those taken for high blood pressure or heart disease may cause potassium levels to drop. Other conditions including severe diarrhea or vomiting, anorexia, alcoholism and congestive heart failure may also lead to hypokalemia.

Dangers of Benzene

Foods and soft drinks that contain potassium benzoate contain both potassium and benzoate salt. While benzoate by itself appears to be harmless, certain chemical reactions may convert it into a more harmful compound called benzene. According to the FDA, when benzoate is exposed to light and heat in the presence of vitamin C, it can be converted into benzene. Many soft drinks contain both potassium benzoate and vitamin C, resulting in residual amounts of benzene. According to the American Cancer Society, benzene is considered a carcinogen, meaning that it is thought to either cause cancer or encourage its growth.

FDA Stance on Potassium Benzoate

The FDA has determined that beverages that contain both potassium benzoate and vitamin C contain minimal amounts of benzene. The Environmental Protection Agency defines safe drinking water as having less than 5 parts per billion, or ppb, of benzene. Accordingly, the FDA has adopted this maximum allowable limit for consumer-based beverages.

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