"Antinutrients" such as oxalic acid might not be that bad. Oxalic acid chelates iron, which might be positive, since we usually consume more iron than we need and it can accumulate. It also binds with calcium.

Look at phytic acid (IP6), an antinutrient, and the fact that it might treat cancer.

I like so much my cooked spinach, I don't want it to be bad!