Is Low-Dose Oral Cobalamin Enough to Normalize Cobalamin Function in Older People?


Address correspondence to Angela Garcia, MD, PhD, FRCP(C), Department of Medicine (Geriatrics), Queen's University, St. Mary's of the Lake Hospital, 340 Union Street, P.O. Box 3600, Kingston, Ontario, Canada, K7L 5A2. E-mail:


OBJECTIVES: To investigate whether the use of low-dose oral cobalamin (Cbl) supplements by older persons, as frequently found in multivitamin preparations, affects their Cbl serum concentrations and function, determined by measurements of the serum Cbl-related metabolites methylmalonic acid (MMA), homocysteine (HCYS), and methylcitric acid (MCTR).

DESIGN: Cross-sectional study.

SETTING: Community.

PARTICIPANTS: Two hundred forty-two independent, active, community-living, older adult volunteers recruited from community events and activities for seniors.

MEASUREMENTS: We systematically collected data on vitamin supplement intake, diet, medications, and medical and surgical history. Serum was obtained for Cbl, MMA, HCYS, and MCTR, and creatinine and hematological parameters.

RESULTS: Serum levels of Cbl were significantly higher in subjects on oral Cbl supplements (2–37.5 μg/day). Similarly, serum levels of the metabolites MMA, HCYS, and MCTR were also lower in subjects on Cbl supplementation. Intake of low-dose oral supplements of Cbl significantly reduced the odds of low Cbl levels or high MMA. The relationship between Cbl supplement dosage and the biochemical parameters was dose dependent.

CONCLUSION: Oral Cbl (2–37.5 μg/day) intake by community-dwelling healthy older adults is associated with higher serum levels of Cbl and improved or normalized Cbl function, as indicated by lower concentrations of the metabolites MMA, HCYS, and MCTR. Use of low-dose oral Cbl replacement therapy might be sufficient to prevent Cbl deficiency in a large proportion of this population.