From the abstract: > This study provides factual information about the animal protein contribution to total proteins compatible with meeting all nutrient-based

From the abstract: > This study provides factual information about the animal protein contribution to total proteins compatible with meeting all nutrient-based recommendations at no additional cost and shows that it varies between 45% and 60% depending on the group of adults considered. TL;DR, if you replace animal protein with non-animal protein, you're probably losing out on other nutrients. Also: > In Model Set#2, for women and men over 65 years (C and E), decreasing animal protein contribution to total proteins below 55% and 60% respectively led to protein levels below recommend levels. This suggests that non-animal proteins are not used by the body as efficiently as animal proteins. I don't think this means your protein must by animal-based, but if you're substituting vegan options, you probably need more protein than you think, and also need additional vitamin supplements, as well.