Comparing the effectiveness of oral supplementation and intramuscular injection of vitamin B12 for treating cobalamin deficiency: systematic review and meta-analysis

Introduction: The common treatments for vitamin B12 (Vit.B12) deficiency are oral supplementation (OS) and intramuscular (IM) injection. However, there have been debates on which treatment is more effective. Therefore, this analysis is aimed at comparing the effectiveness of OS and IM injection using systematic review and meta-analysis. Methods: A search was undertaken in the Cochrane Library, MEDLINE, EMBASE, and KoreaMed for randomised controlled trials (RCTs) on the study subject. We included papers that compared OS and IM injection methods for vitamin B12 treatment for cobalamin deficient patients. Changes in vitamin B12 serum levels before and after the treatments were compared. SPSS program version 18.0 and Review Manager 5.2 were used. Results: The search revealed only three appropriate studies for our analysis, involving a total of 141 patients, out of whom, 66 were given OS and 75 IM injection. The standardised mean difference (SMD) between OS and IM injection was 0.14 (95% CI = -0.20, 0.48, p = 0.42). In considering tolerability, adverse events, and cost, OS was found to be better than IM injection. Conclusions: OS is recommended over IM injection for Vit.B12 treatment method