Not trying to be funny, but I think it depends on the quantity of spinach. If you quoted a quantity in comparison to another vegetable then it may be easier to say.It is true that spinach it high in iron and other things, but how much is needed to feed four?
I am sure, drochit, that your first assesment may be somewhere near. I remember my mother saying " Remember, it is not what you might or might not do or say or even turn your back after eight o'clock in the morning after the night before until all your nurishment and nutriment and don't you forget it". And I never have.
The whole spinach & popeye thing comes about from a typing error in a nutrition sheet put about but the US goverment many years ago....in the error the spinach was given ten times it's proper amount of Iron by an accidentally placed decimal point....So probably not!