Can you name some food additives that are synthesized from non-edible substances?

The grosser the non-edible substance, the better. Background story:

My coworker sees me buying a Naked juice and tells me they use formaldehyde to stabilize the drink and lengthen its shelf life. Skeptical, I do some googling when I get home and find that this myth is an amalgamation of two truths: 1) formaldehyde is sometimes used as a shelf-life extender… but in Southeast Asia, and it’s not like it’s on the up-and-up, but is something they are trying to eradicate. And 2) Naked adds vitamin B5 to their juice, which is synthesized from formaldehyde – but they do not, of course, add actual formaldehyde. (This caused a furor last year and Naked took the all-natural stamp off their label).

So I go back and explain this to my coworker, who responds with willful irrationality: to her, “formaldehyde derivative” ＝ “formaldehyde,” even though she agreed with me when I pointed out that compounds do not retain properties of their chemical precursors and that you can really make anything into anything with the magic of multiple titration. She says, Yeah that’s true, but I’m still not going to drink it – formaldehyde, yuck.

Her response and others like it drive me nuts because I happen to be a big proponent of healthy eating, unprocessed foods, organic and local foods, etc etc, and responses like hers weaken our side’s position and fuel the other side’s by making us look like irrational, reactionary hypochondriacs. This is an image health food folks ought to discourage if we want to be taken seriously.

But this particular conversation about Naked not containing formaldehyde has obviously hit a brick wall, so my plan is to inundate my coworker with knowledge of other commonly eaten compounds that come from scary-sounding non-edible substances. This is an unsurprisingly difficult thing to google, though, so…any chem majors out there?

Other suggestions for combatting willful irrationality are also welcome.