2. Absorption Of The Vitamin Is Limited
Vitamin B12, bound to protein in food, is released by the activity of hydrochloric acid and gastric protease in the stomach. In healthy individuals, about 50% to 60% of the vitamin B12 consumed is absorbed.
The capacity of intrinsic factor, a gastric glycoprotein that aids in B12 absorption, is limited. When oral doses of B12 exceed 1 to 2 mcg at a time, the body’s ability to absorb the nutrient decreases. Therefore, obtaining multiple small doses through food or a larger supplemental dose is recommended to reach optimal B12 levels.