For decades, Americans believed that we had the world's healthiest and safest diet. We worried little about this diet's effect on the environment or on the lives of the animals (or even the workers) it relies upon. Nor did we worry about its ability to endure -- that is, its sustainability.
That didn't mean all was well. And we've come to recognize that our diet is unhealthful and unsafe. Many food production workers labor in difficult, even deplorable, conditions, and animals are produced as if they were widgets. It would be hard to devise a more wasteful, damaging, unsustainable system.