Corn syrup is a light or dark sweet syrup consisting mostly of glucose that is made from cornstarch that is processed with enzymes and acids. Light corn syrup is clarified to make it colorless and clear; dark corn syrup has added coloring and caramel flavoring, plus a stronger flavor. High-fructose corn syrup is a variation on the syrup that contains other enzymes that convert glucose into fructose, making it sweeter.

Corn syrup's big trick is that it inhibits crystallization, lending a smooth texture to and extending the shelflife of processed foods. It is found in many commercially prepared foods, like soft drinks, ketchup, jam, breakfast cereals, candy bars, crackers, ice creams and baby formula, to name a few. Many nutritionists believe that highly refined high-fructose corn syrup is worse for you than regular sugar and is a leading cause of obesity in America.