From the Guidelines
Vitamin B12 supplementation is crucial for individuals with deficiency or those at risk, and the recommended treatment involves administering hydroxocobalamin 1 mg intramuscularly, with the frequency and duration of treatment depending on the presence of neurological involvement. For people with neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then every 2 months 1. In contrast, for people with no neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered three times a week for 2 weeks 1. After treatment of vitamin B12 deficiency, maintenance treatment with 1 mg intramuscularly every 2–3 months lifelong is recommended 1. Key populations at risk of vitamin B12 deficiency include strict vegetarians and vegans, older adults, individuals with gastrointestinal disorders, those who have undergone gastric surgery, and people taking certain medications like metformin or proton pump inhibitors. Supplementation is vital because vitamin B12 is essential for nerve function, DNA synthesis, and red blood cell formation, and deficiency can lead to anemia, neurological damage, and cognitive impairment. While parenteral nutrition should provide at least 5 mg cyanocobalamin per day 1, and enteral nutrition should provide at least 2.5 mg cyanocobalamin per day in 1500 kcal 1, these recommendations are more relevant to specific clinical contexts, such as nutrition support, rather than general supplementation guidelines. In real-life clinical practice, it is essential to prioritize the treatment of vitamin B12 deficiency based on the presence of neurological involvement and to provide lifelong maintenance therapy to prevent long-term complications.
From the FDA Drug Label
1 mg per day may result in hematologic remission in patients with vitamin B12 deficiency. Patients with pernicious anemia should be informed that they will require monthly injections of vitamin B12 for the remainder of their lives. A vegetarian diet which contains no animal products (including milk products or eggs) does not supply any vitamin B12. Patients following such a diet, should be advised to take oral vitamin B12 regularly The need for vitamin B12 is increased by pregnancy and lactation. Amounts of vitamin B12 that are recommended by the Food and Nutrition Board, National Academy of Science-National Research Council for pregnant women (4 mcg daily) should be consumed during pregnancy. Amounts of vitamin B12 that are recommended by the Food and Nutrition Board, National Academy of Science-National Research Council for lactating women (4 mcg daily) should be consumed during lactation. Intake in children should be in the amount (0.5 to 3 mcg daily) recommended by the Food and Nutrition Board, National Academy of Science-National Research Council.
The recommended vitamin B12 supplementation is as follows:
- Pernicious anemia: monthly injections of vitamin B12 for life
- Vegetarian diet: oral vitamin B12 regularly
- Pregnancy: 4 mcg daily
- Lactation: 4 mcg daily
- Children: 0.5 to 3 mcg daily 2
From the Research
Vitamin B12 Supplementation Recommendations
- The optimal long-term management of B12 deficiency with intramuscular therapy is not well established, but the British National Formulary guidelines suggest 1000 µg intramuscular hydroxocobalamin once every two months after the initial loading 3.
- For individuals with B12 deficiency due to reduced dietary intake, oral supplementation is recommended 3.
- In cases of B12 malabsorption, parenteral (intramuscular) supplementation is preferred over oral supplementation 3.
- A study found that a sublingual dosage of 50 µg/day (350 µg/week) of cobalamin was effective in restoring adequate serum concentrations of vitamin B12 in vegans and vegetarians with a marginal deficiency 4.
- Another study recommended that parenteral regimens use 1000 micrograms cyanocobalamin: 5 or 6 biweekly injections for loading, and once-a-month for maintenance 5.
- Oral therapy with 300-1000 micrograms per day may be therapeutically equivalent to parenteral therapy 5.
- A dose-finding trial found that daily oral doses of 647 to 1032 µg of cyanocobalamin were associated with 80% to 90% of the estimated maximum reduction in the plasma methylmalonic acid concentration 6.
- A study found that oral cobalamin treatment with 1000 micrograms per day was effective in normalizing serum cobalamin levels in older patients with cobalamin deficiency related to nutritional deficiency and food-cobalamin malabsorption 7.
Special Considerations
- Clinical and patient experience suggests that up to 50% of individuals require individualized injection regimens with more frequent administration to remain symptom-free and maintain a normal quality of life 3.
- 'Titration' of injection frequency based on measuring biomarkers such as serum B12 or MMA should not be practiced 3.
- There is currently no evidence to support that oral/sublingual supplementation can safely and effectively replace injections 3.