It was Christmas week 1990 in Oakland. Steven Bloom was wandering through The Lot, that timeless gathering of hippies that springs up in the parking lot before every Grateful Dead concert, when a Deadhead handed him a yellow flyer.
Because of the general safety of the vitamin, upper limits for normal intake do not exist. If your blood values for the vitamin fall below a range of 170 to 250 picograms per milliliter, you may develop a B12 deficiency.
If you begin early on, then you should start seeing results from vitamin B12 before long, depending on how much vitamin B12 you need in order to achieve a normal level.Normal vitamin B12 levels are about 200 â 900 pg.f you begin early on, then you should start seeing results from vitamin B12 before long, depending on how much vitamin B12 you need in order to achieve a normal level.