Therapeutic window

And we still managed to miss it with vitamin E in, what, the early 2000s?

Which is precisely why the therapeutic window, the narrow band between minimum effective dose and toxicity, matters more than the question of how much you can take.

That tension is what we're really sitting with here

It makes it sound tidy, and it isn't, right? Because the body doesn't experience dose like a ruler.

The efficacy curve and the toxicity curve are driven by different mechanisms, different receptors, different tissue targets, so they rise and fall independently.

When the toxicity curve starts steepening right around the efficacy plateau, every milligram you add past that point is almost no additional benefit against a sharply rising risk

So the therapeutic window is literally the gap between those two curves

The favorable gap, yes.