People are not made to eat vegan diets and lots of raw foods. More accurately, we did not evolve that way. We are not gorillas. We can’t eat mostly uncooked leaves and similar. Though we are omnivores, that doesn’t mean we can consume only a tiny and nutritionally-deficient slice of our usually extremely varied diet.
That said, vegetarianism is fine if you’re careful. However, veganism is almost certainly long-term harmful to anyone who sticks to it, and definitely very harmful to children.