Sure. Specific, well-studied examples abound. You can get scurvy, or gout, or type II diabetes, or other problems from your diet. But "billions" of people don't get scurvy or gout.

If you want to use some kind of idiosyncratic definition of "sick" that pronounces somewhere between a substantial minority and a majority of the world as "sick" at any given time, I guess I can't stop you. But as a practical matter, we're comparing shake-guy's food to the other foods that people actually eat, not to whatever your idea of the best diet in the world is.

Historically speaking, I don't think that man ate too much of a variety over the course of a given day, maybe weeks... And the guy mentions he does eat a couple times a week. I couldn't do it... but without high yield GM crops, we couldn't even feed 1/2 of the world's population, anything that stretches that isn't a bad thing...