RESUMO
BACKGROUND: First isolated as cyanocobalamin in 1948, vitamin B12 has been explored for pain treatment almost since its discovery. With the advent of the opioid epidemic, safer treatments for pain are needed. OBJECTIVES: Our objective was to compile the latest information on potential mechanisms from animal studies and clinical trial data on vitamin B12 for the treatment of pain conditions. STUDY DESIGN: We conducted a narrative review. METHODS: PubMed was searched using the terms "methylcobalamin pain", "hydroxycobalamin pain", "cyanocobalamin pain", and "vitamin B12 pain." Animal studies that identified mechanisms of action for the effects of pain were collected. Clinical trials utilizing larger, pharmaceutical doses of vitamin B12 (> 100 µg/dose) in pain treatment were identified and reviewed. RESULTS: Animal studies support multiple beneficial effects of vitamin B12 including the regeneration of nerves and the inhibition of cyclooxygenase enzymes and other pain-signaling pathways. In addition, animal studies have demonstrated synergistic benefits of vitamin B12 combined with other pain medications, including nonsteroidal anti-inflammatory drugs and opiates. Clinical trials provide evidence for the effectiveness of vitamin B12 for the treatment of low back pain and neuralgia, although data is still fairly limited and optimal treatment regimens have not been identified. LIMITATIONS: More large, double-blind placebo-controlled trials are needed to fully establish efficacy and best dosing parameters. CONCLUSION: Vitamin B12 may prove to be an adjunctive or integrative treatment for pain conditions. While more research is needed, considering the low incidence of side effects and overall safety, B12 may be an additional tool to consider for pain treatment. KEY WORDS: Vitamin B12, cyanocobalamin, methylcobalamin, hydroxycobalamin, pain, chronic pain, neuropathy, low back pain.
