Sodium benzoate is a chemical used as a preservative in for several types of food, including margarine, soft drinks, pickles, jelly and jam.
Also used in herbal and fruit juices.
Although sodium benzoate is usually safe, it may cause mild side effects in certain individuals. Sodium benzoate is also commonly mixed together with another chemical, sodium phenylacetate, and used to treat a condition known as hyperammonemia, which is characterized by excess levels of ammonia in the blood. The mixture of sodium benzoate and sodium phenylacetate may cause more side effects than sodium benzoate alone.
When used alone as a preservative, sodium benzoate rarely causes side effects, even when consumed in large doses of up to 50 g, reports Oregon State University. In certain individuals, nausea and vomiting may occur. In rare cases, sodium benzoate can irritate existing stomach ulcers and cause mild hyperventilation, possibly leading to dizziness and lightheadedness, according to the Hazardous Substances Data Bank of the National Library of Medicine.