Vitamin b12 dosage for adults
Pro Research Analysisby 
Searched over 200M research papers
Optimal Vitamin B12 Dosage for Adults: A Comprehensive Review
Recommended Daily Intake of Vitamin B12 for Adults
The recommended daily intake of vitamin B12 for adults has been a subject of extensive research and revision. According to the D-A-CH reference values, which are regularly updated by the nutrition societies of Germany, Austria, and Switzerland, the estimated daily intake for adults is set at 4.0 µg/day. This value is based on adequate serum concentrations of holotranscobalamin and methylmalonic acid, which are biomarkers for vitamin B12 status1. Similarly, the European Food Safety Authority (EFSA) has set an Adequate Intake (AI) for cobalamin at 4 µg/day for adults, based on various biomarkers of cobalamin status and observed mean intakes in several EU countries3.
Vitamin B12 Requirements in Older Adults
The requirements for vitamin B12 can vary significantly with age. For adults over 50 years of age, it is recommended to consume vitamin B12 in its crystalline form, which does not require gastric acid or enzymes for initial digestion. This is particularly important as the prevalence of vitamin B12 deficiency increases in the elderly due to atrophic gastritis, which impairs the absorption of protein-bound vitamin B12 from natural food sources. A clinical trial suggests that an oral dose of 500 µg/day of crystalline vitamin B12 is needed to reverse biochemical signs of deficiency in older adults4.
Bioavailability and Daily Losses of Vitamin B12
The bioavailability of vitamin B12 from food sources varies widely, ranging from 4.5% to 83% depending on the food type and the dose consumed. Daily losses of vitamin B12 in healthy adults and the elderly range from 1.4 to 5.1 µg. To compensate for these losses, vitamin B12 intakes may need to range from 3.8 to 20.7 µg/day5 6. This wide range indicates that individual requirements can vary based on several factors, including dietary habits and physiological conditions.
Special Considerations for Specific Populations
Pregnant and Lactating Women
For pregnant and lactating women, the requirements for vitamin B12 are slightly higher due to the needs of the fetus and the loss of vitamin B12 through breast milk. The D-A-CH reference values recommend an intake of 4.5 µg/day for pregnant women and 5.5 µg/day for lactating women1. Similarly, the EFSA recommends an AI of 4.5 µg/day for pregnant women and 5 µg/day for lactating women3.
Post-Gastric Bypass Patients
Patients who have undergone Roux-en-Y gastric bypass surgery often require higher doses of vitamin B12 due to impaired absorption. Studies suggest that oral supplementation doses of 1000 µg/day are sufficient to prevent deficiency in most of these patients8.
Conclusion
The optimal dosage of vitamin B12 for adults generally ranges around 4.0 µg/day, with higher doses recommended for older adults, pregnant and lactating women, and individuals with specific medical conditions such as those who have undergone gastric bypass surgery. The variability in bioavailability and daily losses of vitamin B12 underscores the importance of personalized dietary recommendations to ensure adequate intake and prevent deficiency.
Sources and full results
Most relevant research papers on this topic
The Revised D‐A‐CH‐Reference Values for the Intake of Vitamin B12: Prevention of Deficiency and Beyond
The revised D-A-CH reference values for vitamin B12 intake in adults are 4.0 g d1 for adults, based on adequate serum concentrations of holotranscobalamin and methylmalonic acid.
Observational Study
Very Rigorous JournalSTUDIES ON THE MINIMUM DAILY REQUIREMENT FOR VITAMIN B12. HEMATOPOIETIC RESPONSES TO 0.1 MICROGM. OF CYANOCOBALAMIN OR COENZYME B12, AND COMPARISON OF THEIR RELATIVE POTENCY.
The minimum daily adult requirement for vitamin B12 remains unclear, but a reticulocyte response to 0.1 microgram of cyanocobalamin is sufficient for patients with pernicious anemia in relapse.
Scientific Opinion on Dietary Reference Values for cobalamin (vitamin B12)
The EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) has set an Adequate Intake for cobalamin at 4 g/day for adults, with AIs for infants, children, and pregnancy and lactation ranging from 1.5 to 5 g/day.
Highly CitedWhat is an adequate dose of oral vitamin B12 in older people with poor vitamin B12 status?
An oral dose of 500 micrograms/day of crystalline vitamin B12 is needed to reverse biochemical signs of vitamin B12 deficiency in older adults.
Systematic Review on Daily Vitamin B12 Losses and Bioavailability for Deriving Recommendations on Vitamin B12 Intake with the Factorial Approach
Daily vitamin B12 losses in adults and elderly range from 1.4 to 5.1 g, and recommended intake ranges from 3.8 to 20.7 g to compensate for these losses.
Systematic Review
Vitamin B12 intake and status and cognitive function in elderly people.
Current evidence on the relationship between vitamin B12 intake and cognitive function is insufficient for developing vitamin B12 recommendations.
Systematic ReviewOral Vitamin B12 Supplementation After Roux-en-Y Gastric Bypass: a Systematic Review
Oral vitamin B12 supplementation doses of 1000 g daily may be adequate for preventing deficiency in adult RYGB patients, while doses of 15 g daily are insufficient.
Systematic Review
Rigorous JournalA 2‐Year Randomized Controlled Trial With Low‐Dose B‐Vitamin Supplementation Shows Benefits on Bone Mineral Density in Adults With Lower B12 Status
Low-dose B-vitamin supplementation for 2 years had no overall effect on bone mineral density, but improved B-vitamin status may have specific benefits for bone health in adults with lower B12 status.
RCTVery Rigorous JournalDietary Intake and Status of Vitamin B12 in Slovenian Population
Vitamin B12 deficiency is prevalent in elderly individuals, particularly males, and requires additional attention.
Observational StudyVery Rigorous Journal