This is the first time I've heard that. I know a number of vegetarians who specifically had b12 deficiency, and every single time, the answer was that we could only get b12 from animal products. One of them gets b12 supplements aware that it's the only animal product she consumes.

I checked Wikipedia though, and it agrees with you, which makes me wonder even more why I've heard this exact same experience from several unconnected vegetarians.