Adhering to a strict vegan diet is tough, especially in the age of additives and highly processed foods. Just because you’re avoiding the products that are obviously derived from animals—meat, cheese, eggs, the list goes on—doesn’t mean you aren’t consuming ingredients that are secretly nonvegan. (Perhaps your favorite vintner uses fining agents containing fish bladders, for example. That glass of wine, therefore, is nonvegan. Go figure, right?) We came across many of these ingredients while conducting research for our new book, Vegan for Everybody. To help you avoid some common pitfalls, we’ve developed a primer on ingredients and products that you think are vegan that might actually be nonvegan.