Is low-dose oral cobalamin enough to normalize cobalamin function in older people?
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 microg/day). Similarly, serum levels of the metabolites MMA, HCYS, and MCTR were also lower in subjects on Cbl supplem
