Yes, I’m pretty sure a lion would die if he tried eating only plants, while I’d imagine a cow would die on a meat diet. I’m less well versed on non-human animal diets though, as I’ve never needed to give it a lot of thought.
I do know that humans can be very strong, fit and healthy on a plant-based diet, as confirmed by the world’s medical institutions, and demonstrated by vegan athletes of all types.
Well fantastic - best to go for the one with the least impact to the environment and suffering then!
To make one redundant point, a nice thing about the less natural sourcing of things is that exact dosages can be measured during synethesis - so when tree bark is swapped out for aspirin, opium for morphine etc. you can get reliable, pure dosages for medicine. I don’t think that’s really very important for vitamins of course.