Nothing wrong with vegan food as a side-dish for a nice chunk of meat . A bit more seriously, we are designed to be omnivores. That "omni" thingy includes meat and fat as well. BTW the first and last fully vegan humanoids, the Paranthropus robustus chewed nuts, roots and bulbs and got extinct eventually, while their scavenging cousins the Australopithecus africanus happily turned to our progenitors.