Derek Lowe's reaction to Panera's dopey (and misleading) sodium benzoate ad campaign

If you Google “sodium benzoate”, prepare yourself for a firehose of stupidity. There’s a long list of sites that are convinced that while benzoic acid is a fresh, healthy, natural ingredient, that sodium benzoate is a devilish industrial chemical that will rot your soul. No, really, that’s pretty much how it goes, and since I know that the great majority of the readers here have a good understanding of acid/base chemistry, you all must be furrowing their brows in puzzlement about that one. I’m with you. I think that my favorite, in a way, is the assertion that when sodium benzoate is exposed to ascorbic acid, that it immediately converts to benzene, which cues up a look at benzene’s (most definitely alarming) toxicity. The source for this would have to be this paper from 2008, which analyzed a long list of beverages for benzene contamination, and found that the only detectable levels were in carrot juice intended for infants. Benzene levels correlated with copper and/or iron levels, and the authors believe that the benzoic acid in carrots is catalytically decarboxylated to a small extent during the heat treatment of the juice. But even the sites that don’t bring that up generally work in something about how sodium benzoate causes Alzheimer’s, Parkinson’s, multiple sclerosis, cancers of all types, you name it. And you thought only aspartame could do it all. Somehow, turning fresh, pure benzoic acid into its sodium salt puts the Curse of the Vat onto it, and this evil stain can never be removed, as we all know.

Benzoic acid is found (as a completely natural metabolite and intermediate) in a huge variety of foods, especially fruits and vegetables – berries are particularly high in it, but it’s also found in aromatic spices such as cinnamon and allspice. There’s not much in meat, but it is found in seafood, and in milk, particularly in fermented milk products such as completely natural, non-GMO yogurt made by people wearing unbleached hemp clothing and singing to each other about their feelings. OK, I’ll try to resist going off like that again (it’s difficult), but it’s certainly true that the bacterial metabolic pathways in fermented milk products like cheese and yogurt produce a good amount of benzoate. (If you’re wondering, chemically, where it comes from, it’s apparently via the microbial breakdown of hippuric acid and phenylalanine, and indirectly from tyrosine as well).