Animal-based proteins are complete versus plant-based ones which may be incomplete.
Milk and rennet are both animal-based products, but they also have vegetarian and vegan alternatives.
Since vegans avoid all animal-based products, all animal source milk products are off limits.
There are two forms of iron for the body: "heme" and "non-heme." The former is derived from the hemoglobin of animal-based foods, while the latter refers to iron from grains, vegetables, and legumes.
Main food sources of B12 are animal-based, such as red meat, poultry, shellfish, dairy, and eggs.