My girlfriend and I were geeking out over a couple of facts relating to just how much Italian food must have changed. Marco Polo (anecdotally?) brought the concept of pasta back to Europe from China. Also, tomatoes are native to South America. Seriously, if you take away pasta and tomatoes from Italian food then what is left? It couldn't even be steak and chips, because potatoes are also native to South America.
So what does the archaeological and written record say about Roman/Italian food before these two central staples of their diet? What was the staple diet back when it consisted of foods native to the area now known as Italy?
Italian food prior to the Columbian Exchange happens to be one of our most (if not the most) frequent food history questions! If anyone else would like to put their oar in, please don't hesitate to do so, as More Can Always Be Said on the tomato's influence on Italian food.
For the meantime, OP, you may be interested in this previous thread on pre-tomato Italian food, encompassing a post roundup from u/jschooltiger and an overview by u/Grombrindal18.
On the pasta front, u/wotan_weevil has you covered: