When our body has had enough iron when consuming plant based foods, our body can actively block iron absorption. (nutritionfacts.org)
This article makes it sound like it is almost impossible to get enough protein and the required essential amino acids by only consuming plant foods. (westonaprice.org)
In addition, cats will often seek out and consume plant matter on their own, much to the frustration of many cat owners. (cat-lovers-only.com)