Benzoic Acid vs Mono- and Diglycerides: 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 Mono- and Diglycerides?

Mono- and diglycerides are emulsifiers derived from glycerol and fatty acids, most commonly sourced from soybean, palm, or sunflower oil. They are partial glycerides that exist between monoglycerides (one fatty acid chain) and diglycerides (two chains). They are chemically similar to fats but are not classified as trans fats even when made from partially hydrogenated sources.

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.

Mono- and Diglycerides: Generally recognized as safe at typical food levels. However, mono- and diglycerides can be derived from partially hydrogenated oils, meaning they may carry trace trans fats that do not appear on the trans fat label because they are classified as emulsifiers, not fats. Some researchers have noted this labeling gap. A 2019 study published in Lipids in Health and Disease noted potential concerns with industrial trans fatty acids in these additives. For most consumers, exposure is low, and regulatory agencies including FDA and EFSA consider them safe at permitted levels.