Vegans may want to think twice about what they use to sweeten their coffee because casein, a type of protein found in dairy milk, is actually used to make many non-dairy creamers.

Casein is a major protein found in mammalian milk. It helps give creamer its signature white color and a hint of dairy flavor.

A label of "non-dairy" doesn't always mean a product is wholly milk-free. The Food & Drug Administration doesn't have a regulatory definition for the term non-dairy or dairy-free.

A creamer could be labeled non-dairy if it were lactose-free, but it could still contain casein so long as the ingredients label indicates that it's a derivative of milk.