Sodium benzoate is a preservative.  It is used most prevalently in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also found in alcohol-based mouthwash.

Sodium benzoate is found naturally in cranberries, prunes, greens, plums, cinnamon, ripe cloves, and apples.

In combination with ascorbic acid (vitamin C), sodium benzoate and potassium benzoate may form benzene, a known carcinogen.

Professor Peter Piper of the University of Sheffield notes that sodium benzoate by itself can damage and inactivate vital parts of DNA in a cell's mitochondria.

Sodium benzoate is a common allergen. People who suffer from asthma, or who have recurrent rashes (urticaria) may be sensitive to sodium benzoate and have allergic reactions.

Meal Genius does not endorse products containing sodium benzoate.

References

Piper PW Yeast superoxide dismutase mutants reveal a pro-oxidant action of weak organic acid food preservatives Free Radic Biol Med 1999 Dec;27(11-12):1219-27. FDA, 2006. "Data on Benzene in Soft Drinks and Other Beverages, " United States Food and Drug Administration. Accessed June 2nd at: http://www.cfsan.fda.gov/~dms/benzdata.html