Today the refounding of the world after the Flood and the covenant with Noah come around in the lectionary. I didn't preach the first reading at Mass this morning, but nonetheless it's a passage I think about sometimes, mainly from the perspective of nutrition.
It is with God's covenant with Noah that human beings receive divine permission to eat animals (excepting the blood.) Our antediluvian counterparts, in the generations from Adam to Noah, were only given the seed-bearing plants and fruits to be their food.
Christianity, then, seems to be beg a dietary question: if our redemption in Christ is the work of restoring the original justice prior to the fall of our first parents, is not the antediluvian diet more appropriate to us than the post-Noachic? In other words, shouldn't Christians be vegans?
Of course, on the other hand, God declared animal food clean in Peter's vision and then commanded Peter to "slaughter and eat" (Acts 10.) Jesus himself is said to have declared all food clean. (Mark 7:19, et al.) St. Paul teaches strongly that food is not a constitutive, but only relative, concern in the Kingdom of God (Romans 14.)
For me, at least on purely theological grounds, by which I mean scripture, it's a question I've never been able to resolve.