But likely true.
From this article: Flavorists, Experts in the Field of Natural and Artificial Flavoring, Work in Top Secret New Jersey Labs
"Products that include flavorists’ laboratory-made concoctions in their ingredient lists are said to account for 90 percent of items bagged and toted home from U.S. grocery stores."
Flavorists use herbs and chemicals to create, recreate and enhance flavours. Their work is done on processed dairy, pre-prepared meats, packaged stuff, fast-food and all the junk and grain-based stuff too.
But, still... That means that in your "average" American diet, only 10% of what you eat is:
10%... And ALL the rest is bread, cake, pasta, jarred sauces, jams, sweets, yoghurts, juices, fizzy drinks, fast food, packaged and pre-cooked stuff...