What are the recommendations for supplementation with Vitamin B12 (Cobalamin)?

From the Guidelines

Vitamin B12 supplementation is recommended for individuals with deficiency, those at risk of deficiency, or those following plant-based diets, with a daily oral dose of 1,000-2,000 mcg (1-2 mg) of cyanocobalamin or alternative forms like methylcobalamin or hydroxocobalamin. For most adults with B12 deficiency, this dose is effective, and for maintenance after correcting deficiency, 1,000 mcg daily or 2,000 mcg weekly is typically sufficient 1. Severe deficiency may require initial intramuscular injections of 1,000 mcg, administered daily for a week, then weekly for a month, followed by monthly injections or high-dose oral supplementation. Vegetarians and vegans should take at least 250 mcg daily or 2,500 mcg weekly. B12 is essential for nerve function, DNA synthesis, and red blood cell formation; deficiency can cause anemia, neurological damage, and cognitive impairment. The body's ability to absorb B12 decreases with age and certain conditions like pernicious anemia, so higher doses may be needed. B12 supplements are generally considered safe even at high doses as excess is excreted, though it's best to consult a healthcare provider before starting supplementation, especially if taking medications or having existing health conditions. Some key points to consider include:

• The importance of treating vitamin B12 deficiency immediately, especially in cases with possible neurological involvement, using hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, then every 2 months 1.
• The need for maintenance treatment with 1 mg intramuscularly every 2–3 months lifelong after treatment of vitamin B12 deficiency.
• The recommendation for vegetarians and vegans to take at least 250 mcg daily or 2,500 mcg weekly of vitamin B12.
• The guidance on supplementation for the prevention and treatment of nutritional deficiencies in patients undergoing bariatric surgery, including vitamin B12 supplementation 1. Overall, the most recent and highest quality study 1 supports the use of vitamin B12 supplementation for the prevention of stroke, particularly in individuals with deficiency or at risk of deficiency, highlighting the importance of adequate vitamin B12 levels for maintaining health and preventing morbidity and mortality.

From the FDA Drug Label

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 recommendations for supplementation with Vitamin B12 (Cobalamin) are 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, 2, 3

From the Research

Recommendations for Supplementation with Vitamin B12 (Cobalamin)

The following are recommendations for supplementation with Vitamin B12 (Cobalamin) based on available evidence:

• Reduced dietary intake of B12 requires oral supplementation 4
• In B12 malabsorption, oral supplementation is likely insufficient, and parenteral (i.e. intramuscular) supplementation is preferred 4
• According to the British National Formulary guidelines, many individuals with B12 deficiency due to malabsorption can be managed with 1000 µg intramuscular hydroxocobalamin once every two months after the initial loading 4
• Oral administration of high-dose vitamin B12 (1 to 2 mg daily) is as effective as intramuscular administration for correcting anemia and neurologic symptoms 5
• Intramuscular therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms 5
• Patients who have had bariatric surgery should receive 1 mg of oral vitamin B12 per day indefinitely 5
• Oral supplementation with 1000 μg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in pernicious anemia 6
• The use of high-dose oral B12 at different frequencies may be considered for long-term treatment 7
• Prophylactic B12 supplementation should be considered for specific high-risk groups 7
• Daily doses of 647 to 1032 mug of cyanocobalamin were associated with 80% to 90% of the estimated maximum reduction in the plasma methylmalonic acid concentration 8

Special Considerations

• Clinical and patient experience strongly suggests that up to 50% of individuals require individualized injection regimens with more frequent administration, ranging from daily or twice weekly to every 2-4 weeks, to remain symptom-free and maintain a normal quality of life 4
• 'Titration' of injection frequency based on measuring biomarkers such as serum B12 or MMA should not be practiced 4
• There is currently no evidence to support that oral/sublingual supplementation can safely and effectively replace injections 4
• The severity of clinical symptoms, the causes of B12 deficiency, and the treatment goals govern decisions regarding the route and dose of B12 therapy 7