Oral vitamin B12 for patients suspected of subtle cobalamin deficiency: a multicentre pragmatic randomised controlled trial

Study answer

What this study found

One month of oral vitamin B12 improved the primary metabolic marker: serum methylmalonic acid fell by 0.13 μmol/l (95% CI 0.06-0.19) more than in the placebo group. Serum vitamin B12 increased significantly, but homocysteine, hematocrit, mean corpuscular volume, and clinical symptom/sign improvement did not show meaningful benefit. After three months off treatment, the methylmalonic acid difference was no longer detectable. The authors concluded that short-term oral vitamin B12 normalizes methylmalonic acid, but the clinical significance of correcting metabolic markers alone remains uncertain.

Study & population

Multicentre pragmatic randomized controlled trial in western Switzerland.

Intervention

The active intervention was oral cobalamin (vitamin B12) 1000 μg daily for 4 weeks, compared with placebo.

Key limitation

The trial was small and short, with only 26 participants in the active arm and limited follow-up after stopping treatment.

View full study detailsView sourceOpen PDF

Original abstract