Benzoic Acid vs Ascorbic Acid: which is worse?

What is Benzoic Acid?

Benzoic acid is a naturally occurring aromatic carboxylic acid found in cranberries, prunes, cinnamon, and many berries. It is used as a preservative against bacteria, yeast, and fungi at pH below 4.5. In the body, benzoic acid is conjugated with glycine to form hippuric acid, which is excreted in urine.

What is Ascorbic Acid?

Ascorbic acid is the chemical name for vitamin C, an essential water-soluble vitamin found abundantly in fruits and vegetables. As a food additive (E300), it functions as an antioxidant preservative, preventing oxidative browning and rancidity. Commercial ascorbic acid is produced by fermentation of glucose, most commonly from corn.

Documented risks

Benzoic Acid: When benzoic acid (or sodium benzoate) is combined with ascorbic acid (vitamin C) in beverages, it can form benzene, a known carcinogen classified as Group 1 by IARC. This reaction is promoted by heat and light. The FDA and EFSA monitor benzene levels in beverages and have set informal guidance limits. A 1999 Lancet publication and the subsequent 2007 'Southampton study' did not directly involve benzoic acid, but sodium benzoate was included in the tested mixture. Some individuals with aspirin sensitivity may react to benzoic acid. The ADI is 5 mg/kg body weight/day.

Ascorbic Acid: Generally recognized as safe. Note: when ascorbic acid is combined with sodium benzoate or benzoic acid in acidic beverages, benzene can form — a Class 1 carcinogen. This combination should be avoided in formulations. As a standalone additive, ascorbic acid is not only safe but nutritionally beneficial. Very high supplemental doses (>2 g/day) can cause diarrhea and kidney stone risk in predisposed individuals.