Translations:Vitamin B12/68/en

Investigations into the intestinal absorption of B₁₂ confirm that the upper limit of absorption per single oral dose is about 1.5 µg, with 50% efficiency. In contrast, the passive diffusion process of B₁₂ absorption — normally a very small portion of total absorption of the vitamin from food consumption — may exceed the haptocorrin- and IF-mediated absorption when oral doses of B₁₂ are very large, with roughly 1% efficiency. Thus, dietary supplement B₁₂ supplementation at 500 to 1000 µg per day allows pernicious anemia and certain other defects in B₁₂ absorption to be treated with daily oral megadoses of B₁₂ without any correction of the underlying absorption defects.