All I can tell you is that when running very high mileage (140+) I was struggling with recovery and upped my protein and it helped a lot - extra chicken and protein shakes.
Then this year I ran 600 miles in Jan while eating a nutirtarian diet - predominately vegan but basically trying to flood the body with as many nutrients as possible from healthy plant sources. My protein intake was lower than before I upped it previously and yet I recovered noticeably better than ever before.
Maybe "bioavailable" was the wrong term (or wrongo!), but I recover better with more salad, more veg, more fruit, more raw food and no meat/dairy. Experiment of one - it works best for me. BUt I know many others who have said the same thing (which is why I tried it).
I suspect the huge number of antioxidants and phytonutrients help with recovery and naturally reducing inflammation. But, whatever is the case, it made a big difference for me.