Oral Vitamin B12 Versus Intramuscular Vitamin B12 for Vitamin B12 Deficiency

A Cochrane review [Abstract] 1 included three studies with a total of 153 subjects. Treatment duration and follow-up ranged between three and four months. The mean age of participants ranged from 38.6 to 72 years. The treatment frequency and daily dose of vitamin B12 in the oral and IM groups varied among trials.

In two trials employing 1000 μg/day oral vitamin B₁₂, there was no clinically relevant difference in vitamin B₁₂ levels when compared with intramuscular vitamin B₁₂. One trial used 2000μg/day vitamin B₁₂ and demonstrated a mean difference of 680 pg/mL (95% CL 392.7 to 967.3) in favour of oral vitamin B12. Two trials reported data on adverse events. One trial stated that no treatment-related adverse events were seen in both the oral and IM vitamin B₁₂ groups. One trial reported that 2 of 30 participants (6.7%) in the oral vitamin B₁₂ group left the trial early due to adverse events. Orally taken vitamin B₁₂ showed lower treatment-associated costs than IM vitamin B₁₂ in one trial. No trial reported on clinical signs and symptoms of vitamin B₁₂ deficiency, health-related quality of life, or acceptability of the treatment scheme.

Comment: The quality of evidence is downgraded by study quality (lack of blinding) and by imprecise results (limited study size).

References

• Wang H, Li L, Qin LL et al. Oral vitamin B₁₂ versus intramuscular vitamin B₁₂ for vitamin B₁₂ deficiency. Cochrane Database Syst Rev 2018;(3):CD004655. [PubMed]