Inherited and acquired vitamin B12 deficiencies: Which administration route to choose for supplementation?

Abstract

Vitamin B12 or cobalamin deficiency is a commonly encountered clinical scenario and most clinicians will have familiarity prescribing Vitamin B12 to treat their patients. Despite the high prevalence of this condition, there is widespread heterogeneity regarding routes, schedules and dosages of vitamin B12 administration. In this review, we summarise the complex metabolic pathway of Vitamin B12, the inherited and acquired causes of Vitamin B12 deficiency and subsequently highlight the disparate international practice of prescribing Vitamin B12 replacement therapy. We describe the evidence base underpinning the novel sublingual, intranasal and subcutaneous modes of B12 replacement in comparison to intramuscular and oral routes, with their respective benefits for patient compliance and cost-saving.

Vitamin B 12

“…Subcutaneous administration is sometimes recommended when intramuscular injections are contraindicated, for instance, in people using anticoagulants. Comparative studies between intramuscular and subcutaneous administration are lacking 21…”

Consensus of the Brazilian Association of Nutrology on diagnosis, prophylaxis, and treatment of vitamin B12 deficiency

“…Drug treatment, whether parenteral (intramuscular or subcutaneous), oral, sublingual, or intranasal, should be started after clinical and/or laboratory evaluation [62]. The chosen route of administration should take into account the underlying disease, the severity of the disability, a greater possibility of treatment adherence, and costs.…”

An Adenosylcobalamin Specific Whole‐Cell Biosensor

“…Unfortunately, vitamin B12 deficiency is quite common due to nutritional imbalance, malabsorption disorders, as well as genetic defects in the uptake, transport, and intracellular processing of vitamin B12. [1] This deficiency has severe consequences ranging from pernicious anemia, [2][3][4] neurological disorders associated with irreversible demyelination of nerve cells, [5,6] and pregnancy complications. [7] The most common treatment for these patients is the oral or parenteral administration of mega DOI: 10.1002/adhm.202300835 doses of up to 1000 μg daily compared to the regular required 1-2 μg per day.…”