Benzoic Acid vs Citric 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 Citric Acid?

Citric acid is a weak organic acid naturally occurring in citrus fruits. Commercial citric acid is produced almost entirely by fermentation of sugar substrates (typically molasses or corn syrup) using the mold Aspergillus niger. It is the most widely used food acidulant and preservative globally, also functioning as a chelating agent and flavor enhancer.

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.

Citric Acid: Generally recognized as safe. Excessive consumption can erode tooth enamel due to its acidic nature — dentists recommend rinsing with water after consuming highly citric drinks. A 2018 report in the journal BMJ Case Reports described a cluster of inflammatory reactions (joint pain, muscle weakness) in individuals who reported reactions specifically to industrially produced citric acid, hypothesizing residual Aspergillus proteins from the fermentation process as a potential cause. This remains a hypothesis without controlled clinical evidence, and regulatory agencies maintain its safety status.