Oral cyanocobalamin for vitamin B12 deficiency in pernicious anemia
What it found
In 26 people with pernicious anemia, a daily oral dose of 1000 micrograms of cyanocobalamin corrected vitamin B12 deficiency in most within one month and kept it corrected for a year.
What they found
Studies in people
Deficiency corrected
After one month, 88.5% of patients no longer had vitamin B12 deficiency. By the end of the 12-month follow-up, all patients had their deficiency corrected.
Blood markers improved
Plasma vitamin B12 rose, while homocysteine and methylmalonic acid levels fell, with improvements seen at one month and maintained throughout the year.
Clinical symptoms resolved
The median time to reverse abnormalities was 1 month for hemolysis, 3 months for macrocytosis and anemia, 3 months for neurologic symptoms, and 4 months for mucosal symptoms.
Similar response by antibody type
Patients with anti-intrinsic factor antibodies and those with only antiparietal cell antibodies responded similarly to oral supplementation.
Compliance and dose adjustments
Adherence was very high, with a median Girerd score of 0. In 3 patients, the dose was reduced to 1000 micrograms per week because of high vitamin B12 levels, and none showed signs of intoxication.
What the authors conclude
“Oral supplementation with 1000 μg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in PA.”
Also in their conclusions
- They conclude that oral cyanocobalamin at a daily dose of 1000 micrograms was highly effective in correcting vitamin B12 deficiency and improving related symptoms in pernicious anemia.
- They state that this study strongly advocates for oral vitamin B12 supplementation at a daily dosage of 1000 micrograms.
- They believe that the oral route should be preferred over intramuscular injections for most patients with pernicious anemia.
How it was done
Pernicious anemia causes poor vitamin B12 absorption, so injections have been the standard treatment. The authors wanted to see if oral cyanocobalamin could work instead, since previous studies were small or short.
They enrolled 26 adults with vitamin B12 deficiency due to pernicious anemia and gave them 1000 micrograms of oral cyanocobalamin daily for 12 months. They measured vitamin B12 status and clinical signs at baseline and at 1, 3, 6, 9, and 12 months.
What it can’t tell you
- This was an open-label study without a comparison group receiving injections, so it cannot directly prove that oral cyanocobalamin is as good as or better than intramuscular vitamin B12.
- The study did not include patients with combined spinal cord sclerosis, so the results may not apply to that specific severe form.
- The findings are from a small group of 26 patients, and larger studies are needed to confirm the results in other populations.
Who paid
- Authors work at
- University Hospital, France; Angers University, France; University of California, United States
The paper
- Title
- Oral vitamin B12 supplementation in pernicious anemia: a prospective cohort study
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Lacombe V, Vinatier E, Roquin G, et al (2024). Oral vitamin B12 supplementation in pernicious anemia: a prospective cohort study. The American journal of clinical nutrition. doi:10.1016/j.ajcnut.2024.05.019Free full textPubMed 38797248DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error