Hi Dolores,
Interesting controversies about B12.
My dad was a physician. He said some people swear by a monthly injection of B12. My mom was one of them. They feel much better with the mega-doses of B12. Other physicians say the B12 injections are worthless.
If Dr. Esselstyn takes 1000 mcg daily, that's an expert opinion in favor of B12. (Another interesting controversy. I used to be on a low fat diet, as advocated by Esselstyn. When I was strict for a couple weeks, I'd get a craving to break the diet. Now I eat enough seeds and nuts, to not be on a low fat diet, in Esselstyn's opinion. Now I don't crave to break the diet.)
Roger Clemens is a baseball star. 60 Minutes interviewed him, and asked him if he ever took steroids. He said his physician injected him with only 2 things. Lidocaine for pain, and vitamin B12. I'm not going to call him up and tell him that it's worthless. I assume he or his doctor know more about B12 than I do, for athletes.
We do know that the requirements for B12 vary greatly, person to person. Pernicious anemia is one extreme example.
Dr. Fuhrman includes 30 mcg of B12 (from methylcobalamin) in his Gentle Care, and lists it at 500% of Daily Value, which agrees with 6 mcg DV you quoted. We also know that an excess of B12 is very benign, so 30 mcg is no harm to most people who may not need that much. That's the idea of a multi-vitamin, to take care of common extra requirements of some people, without harming any others.
The vegan raw foodists insist that they do not need B12 supplements. These folks unfortunately ignore the science. T C Fry, a famous raw foodist, actually died of a B12 deficiency (actually a stroke caused by high homocysteine, caused by B12 deficiency). Dr. Fuhrman saw his charts.
So, to answer your question, Duh, I donno.
Best regards, EngineerGuy