If there was a food or chemical substance that was not listed as a controlled substance either federally or at the state level, and it is never explicitly mentioned in any FDA food guidelines, does that mean that it can be included in food and sold to consumers without any special labeling? What laws regulate whether a chemical substance or plant product can be included in food when it is not explicitly banned or regulated by the FDA, assuming it isn't harmful at amounts present in a normal serving?
What if that substance has potentially harmful effects when taken in much larger amounts than included in a standard serving of the food product? (For instance, caffeine is legal to sell without warning labels, but in excessive doses can result in hospitalization or death). If a product is safe in the suggested serving size, are food processors liable for harm caused when people abuse their products and consume excessive amounts of them?