Harmful Ingredient: Monosodium glutamate. Typically dubbed a healthy, soothing meal, soup truly is one of the least suspicious diet saboteurs of them all. What makes it so addicting? Besides being appealing because of its low cost, many popular brands add monosodium glutamate, a flavoring agent that increases appetite and causes migraines. While we weren’t too shocked to learn that all of Maruchan Ramen Noodles—a popular college staple—are laced with the ingredient, we were miffed to learn that some of Campbell’s condensed soups are loaded with it, too.