From the Guidelines
The daily supplement of vitamin B12 that is considered safe for most adults is 250-350 μg/d or 1000 μg/wk sublingual, as recommended by the Advances in Nutrition journal in 2017 1. When considering vitamin B12 supplementation, it's essential to prioritize the individual's specific needs, which may vary based on age, medical conditions, and medication use.
- The recommended daily intake of vitamin B12 may be higher for certain individuals, such as those with a deficiency, who may require 1000-2000 μg/d sublingual, intramuscularly, or intravenously 1.
- It's also important to note that vitamin B12 supplements come in different forms, including cyanocobalamin and methylcobalamin, which may have varying levels of bioavailability.
- Additionally, certain medications, such as metformin and proton pump inhibitors, may reduce vitamin B12 absorption, requiring higher doses to maintain adequate levels 1.
- Pregnant and breastfeeding women may also have different vitamin B12 requirements, with recommended daily intakes of 2.6 and 2.8 micrograms, respectively.
- However, the study by Advances in Nutrition in 2017 1 provides the most recent and highest-quality guidance on vitamin B12 supplementation, recommending 250-350 μg/d or 1000 μg/wk sublingual for most adults.
- It's crucial to consult with a healthcare provider to determine the best course of treatment and dosing recommendations tailored to an individual's specific situation, as they can assess the individual's overall health and provide personalized guidance.
From the FDA Drug Label
Doses of cyanocobalamin exceeding 10 mcg daily may produce hematologic response in patients with folate deficiency. 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 safe daily supplement amount of B12 is:
- 4 mcg for pregnant and lactating women, as recommended by the Food and Nutrition Board, National Academy of Science-National Research Council 2.
- 0.5 to 3 mcg for children, as recommended by the Food and Nutrition Board, National Academy of Science-National Research Council 2. However, the label does not provide a general safe daily supplement amount of B12 for adults.
From the Research
Daily Vitamin B12 Supplementation
- The safe daily dosage of vitamin B12 supplementation is not explicitly stated in the provided studies, but one study 3 used a dosage of 1000 μg/d of cyanocobalamin to treat patients with pernicious anemia.
- This dosage was shown to be effective in improving vitamin B12 deficiency in patients with pernicious anemia, with 88.5% of patients no longer deficient in vitamin B12 after 1 month of treatment.
- Another study 4 reported a case of toxicity induced by multiple high doses of vitamin B12, with a total dose of 12 mg of cyanocobalamin causing symptoms such as acne, palpitations, and anxiety.
- However, this case involved much higher doses than the 1000 μg/d used in the study 3, suggesting that lower doses may be safer.
Factors Affecting Vitamin B12 Supplementation
- The absorption of vitamin B12 is hindered in pernicious anemia due to intrinsic factor deficiency, making oral supplementation less effective 3.
- However, oral vitamin B12 supplementation can still be effective in treating deficiency, especially at high doses 3.
- The diagnosis of vitamin B12 deficiency can be complex, with multiple tests available, including serum B12, holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements 5.
Population-Specific Considerations
- Vitamin B12 deficiency can affect individuals at all ages, but is more common in elderly individuals and those with restricted dietary intake of animal-derived foods 6, 7.
- Infants, children, adolescents, and women of reproductive age are also at high risk of deficiency in populations with limited access to B12-containing foods 6.