Originally Posted by
noglider
But it's still based on beliefs. I've been on both sides of the fence. I was meatless for 20 or 30 years. I think extremist of any kind is the biggest vice.
B12 comes from meat as I'm sure you know, so purism is useless.
B12 is just one of the concerns, there are other essential nutrients that are almost absent or barely bio-available in plants, like Vitamin D3, ω3s (DHA/EPA), Iron, Zinc, and Calcium.
Basically, a great recipe for fatigue and muscle weakness, which is exactly what the Great Lent diet that I described earlier (no meat, fish, dairy, or eggs) aims for (you are supposed to pray and meditate, not win races).