I've seen an ingredient called "vanillin" in some chocolates, and know it's on the Whole Foods list of unacceptable ingredients. Anything that limits my chocolate intake deserves researching.
At first, I thought the difference between vanilla and vanillin was kind of like the difference between music and muzak, ham and Spam, Paris Hilton and Perez Hilton. It turns out that is not the case.
Vanillin, C8H8O3, is one of many chemicals that is naturally extracted from a vanilla bean (1). In a fermentation process, the vanillin molecule increases in concentration and crystallizes outside the bean(3). However, vanillin is one of many chemicals that is "extracted" from the vanilla bean. Natural vanilla extract contains the vanillin molecule as well as several hundred other organic molecules that are produced when the bean pod is cured. It is the combination of these chemicals that gives vanilla extract its flavor. (2)
In and of itself, I found no real evidence that vanillin was harmful. So why should we be nervous if we see the ingredent "vanillin" on a food package?
Because vanilla is in high demand, vendors often create imitation vanilla (1). Chemists can create a series of reactions, none of which have to do with the vanilla bean, whose final product is the molecule C8H8O3. This is a cheaper and less-time consuming process (2). There are several different processes that produce vanillin or a vanilla-like flavoring, and herein seems to be the problem.
Lignin vanillin is derived from a chemical byproduct of paper-making (3). (Here's the patent for it.)
Ethyl vanillin can be produced using coal tar; this is done primarily in Mexico, where vanilla is a popular tourist item.
An organic chemical called Coumarin is also used as a vanilla substitute. It is not C8H8O3 (vanillin), but has an aroma similar to vanilla extract. It occurs naturally in many plants such as lavender and licorice, and scientists have observed that coumarin acts as a natural pesticide for these plants. Coumarin is an anticoagulant(4). It is also used when preparing rat poison, because high doses of an anticoagulant kill the rats (6). In 1954, the FDA banned the use of coumarin in foods after rodents who were fed the chemical sustained liver damage (5).
The problem with synthetic vanillin seems to be twofold. First, imitation vanilla extract does not have the hundreds of additional substances that real vanilla extract does, thereby diminishing vanilla flavor.
Second, buying imitation vanilla, especially from other countries, means you never know exactly what you're getting. In 1993, scientists performed a thin-layer chromatography test of Mexican and Puerto Rican vanillas that claimed to be pure etract. They found the vanillas had artificial ingredients, including ethyl vanillin and coumarin. (5) (Here I cringe, as I remember a suspicious bottle of vanilla I bought in Veracruz a few years ago.)
When the carbon atoms in lignin vanillin are compared with that of naturally occuring vanillin, there was a difference in carbon isotopes. Natural vanillin has more C-13 atoms than lignin vanillin (2). I am not sure if that is significant, but I do know that isotopes of carbon differ in radioactivity level. If anything, Carbon 12 is the more stable of the two.
The vanilla extract/imitation vanilla problem is a classic example of a really nuanced food question that is rightly subject to skepticism. "Sure, enough of anything will kill you." "Sure, if you feed rats enough of anything they're going to blow a gasket."
Today I made banana muffins and added one teaspoon of vanilla extract for about two dozen muffins. What if I had used lignin vanillin? Isn't C8H803 just that, no matter if it comes from a bean or from the byproduct of papermaking? What if my vanillin was really coumarin? Is 1/24 of a teaspoon of either substance going to be harmful?
It's helpful to remember that nutrition, at its simplest level, is a conversation between cells and molecules. Tiny amouts of substances do have an effect on the body, and most of what you eat passes through your gastrointestinal system into other body systems. Have you ever had a fleck of something suspect in your glass of water? Did you drink it anyway?
Vanillin on the Shroud of Turin?