okay, time for some contention
if you cut apples, lettuce, or certain other things with *any* iron knive (esp carbon), you WILL get contact oxidation, though lemon juice can deal with that
so, there is a correlation. i was just waiting for someone to say something
some stupidly sensitive people might notice that. most won't.
i think one of the reason why MOST won't, is they don't routinely LICK various kinda of metals and/or have a good sense of smell correlated with years of "being aware"... uhm, like me

yaaaaah, uh, i like things. i smell it. i taste things... i can SMELL several flavors of water in the air. "i know snow"...
if you get someone that is stupidly sensitive, they might notice. me? rarely in food because of knives. though the FOOD might notice.
i can slice paper thin apples with a ceramic or glass knive, and they *do not oxidize* unless my work surface had impurities.
do the same thing with *any* steel based knife? you get *brown* apples (or lettuce...)...
clearly, there is a reaction, and based on color alone, i shall call it rust. this, i can generally *taste*
now, in meat? there, is the advantage, as meat is RICH in iron *anyway*. you are not going to taste nothing.
if you mix a red meat knife (of which i include almost anything but veggies and fish), you might notice. however, as a LOT of food is ideally cook on, or in iron cookware, ..., not so much! go figure, eh? bbq grills? steel, iron. cast iron? duh. other? well, depends. mostly? no?
red meat by itself oxidizes ANYWAY, so "iron helper"? no effect.
thank you for tuning into science today and my opinion...
also, my sense of smell is FREAKY. i know you ate that
