I remember seeing news reports of a demented couple, who killed their baby by feeding it nothing but a vegan diet.
If you do not supplement a vegan diet will kill you.
In the case I think you are talking about they were not even letting the poor little baby nurse.
I think a lot of the problems currently in the world come from the simple misunderstanding of one thing. Humans are mammals. That means sex is binary and immutable also we birth live young and nurse them.
I remember that too, such a sad case. I met a fellow at a party many years ago who had a lovely Golden Retriever. Dog was a “vegetarian,” God help that poor animal.
OTOH, I have a lovely new neighbor who is vegan, does not drink coffee either. She’s fun, very cute, and nice to be with. We hope she’ll come out for lady’s lunch with us at a nearby Thai restaurant where all the food is vegan. Delish stuff; and oh, that wonderful Thai Iced Tea.
I eat chicken, beef, turkey, eggs and a couple of days a week have a nice bean burger. I don’t eat pork, but veggie pork in delish sauce is very satisfying once in awhile.
Food really shouldn’t be your religion. ...and then there are Seventh Day Adventists. My first friend in this town was one and took a couple of us to her church where they were having a cooking class. Lovely people and seriously yummy food. She has since become a Catholic.