Casein is the principal protein in milk. It’s found in the milk of all mammals, and, oddly enough, is often found in food items marked ‘non-dairy.’
While the term ‘non-dairy’ might mislead you into believing that the product in question is milk-free, it’s actually a term invented by the dairy industry to indicate less than 0.5 percent milk by weight.
Examples of ‘non-dairy’ products that contain casein are some coffee creamers, whipped toppings, and soy or rice cheeses. Casein helps non-dairy cheese melt. (It also makes it harder to wash the stuff off your dishes afterward.)
Most of the U.S. supply of casein is imported from countries such as New Zealand, Australia, Ireland, and certain European countries. On several dairy industry websites, it is made clear that casein is a highly profitable byproduct of dairy farming, making it essential for vegans to avoid casein wherever possible.