Noah was a vegetarian before the flood, but after the flood God gave him permission to partake of certain clean animal flesh as food - read your bible...
My Bible says in Genesis 9:3 "Every moving thing that lives shall be food for you." No mention of clean or unclean, that came later with Moses. If you believe Noah was previously a veg. as this passage suggests the clean/unclean distinction in the ark loading must have been for sacrifices.