The basics are a no-brainer when you're trying to eat a diet free of animal products. But while things like meat, eggs and cheese are easy to avoid, adhering to a vegan diet is far more nuanced than it can seem -- especially when processed foods with long ingredients lists and difficult-to-pronounce names can disguise animal products.

People for the Ethical Treatment of Animals (PETA) includes a number of products with refined sugar, natural flavors or other ingredients that in some instances can come from animals on its list of "Accidentally Vegan" products. The organization explains the position as follows:

While PETA supports a strict adherence to veganism, we put the task of vigorously reducing animal suffering ahead of personal purity. Boycotting products that are 99.9 percent vegan sends the message to manufacturers that there is no market for this food, which ends up hurting more animals.