Benzoic Acid vs Sodium Propionate: 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 Sodium Propionate?

Sodium propionate is the sodium salt of propionic acid. Like calcium propionate (E282), it is used as an antimicrobial preservative to prevent mold and bacterial spoilage in bread and baked goods. It is also used in poultry and animal feed applications.

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.

Sodium Propionate: The health profile is essentially the same as calcium propionate. The 2019 Science Translational Medicine study implicating propionate in metabolic changes applies to all propionate salts. Behavioral sensitivity concerns that have been anecdotally reported with calcium propionate may similarly apply. At regulated use levels, sodium propionate is considered safe by global regulatory agencies.