The fact is that humans are omnivores. We were not designed to subsist on plant food alone, but to have variety in our diets. Any limitations to our diets are unnatural, regardless of justification. Obviously these restrictions are valid and to be respected. If someone must make some restrictions on their diet for this kind of reason, they should simply diversify their diet within those limitations as much as possible.
Dietary diversity is a goal.
While there are some roadblocks that must be dealt with, adding those roadblocks of your own free will is not a wise choice.