From the FDA Drug Label
Directions Adults 18 years or older: 1,000 mcg (1 tablet) daily preferably with a meal or as directed by your doctor. Persons under 18 years of age: Consult your doctor. The recommended dosing for oral vitamin B12 (cobalamin) supplementation is:
- 1,000 mcg (1 tablet) daily for adults 18 years or older, preferably with a meal or as directed by a doctor.
- For persons under 18 years of age, it is recommended to consult a doctor for guidance on dosing 1.
From the Research
The recommended oral dosage for vitamin B12 (cobalamin) supplementation is 1000 μg daily, as supported by the most recent and highest quality study 2. This dosage has been shown to be effective in improving vitamin B12 deficiency in patients with pernicious anemia, with significant improvement in plasma vitamin B12, plasma homocysteine, and plasma methylmalonic acid concentrations. The use of oral vitamin B12 supplementation has been found to be as effective as injections for most patients, even those with mild malabsorption, due to the absorption of a small percentage of high-dose oral B12 through passive diffusion 3, 2. Some key points to consider when prescribing oral vitamin B12 supplementation include:
- Treatment duration depends on the underlying cause, with lifelong supplementation necessary for conditions like pernicious anemia or after certain gastric surgeries, while temporary supplementation may suffice for dietary deficiency.
- Lower maintenance doses of 100-500 mcg daily may be sufficient after correction of deficiency.
- Cyanocobalamin is the most common and stable form available over-the-counter, though methylcobalamin and hydroxocobalamin are also effective options.
- B12 supplements are water-soluble and have minimal risk of toxicity even at high doses. It's worth noting that patients with severe malabsorption conditions may require injectable B12, and that oral supplementation may not be suitable for all patients 4, 5. However, based on the most recent and highest quality evidence, oral vitamin B12 supplementation at a dosage of 1000 μg daily is a effective and safe treatment option for most patients with vitamin B12 deficiency 2.