Think about it how many canned food would you need to get your blood to a resonable level? It only gives you 200 blood, thats nothing, a few hits from a zombie and your down 500 blood, not to mention the fact you start to bleed almost instantly, thats what another 2000 blood gone before you can bandage our self? Also, finding something to kill for meat is very rare, not to mention the fact you need a hunting knife to obtain the meat, an axe to obtain wood and a box of matches to get the whole thing going, its just an unreliable sources of blood