Long-Term Effects of Vitamin B12, Folate, and Vitamin B6 Supplements in Elderly People with Normal Serum Vitamin B12 Concentrations

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Abstract
Background: In the elderly, deficiencies of folate, cobalamin (vitamin B12) and pyridoxal phosphate (vitamin B6) are common. The metabolites homocysteine, methylmalonic acid, 2-methylcitric acid and cystathionine have been reported to be sensitive markers of these vitamin deficiencies. Objective: The long-term (269 days) effect of an intramuscular vitamin supplement containing 1 mg vitamin B12, 1.1 mg folate, and 5 mg vitamin B6 on serum concentrations of homocysteine (tHcy), methylmalonic acid (MMA), 2-methylcitric acid (2-MCA), and cystathionine (Cysta) was studied in 49 elderly subjects with normal levels of vitamin B12. Methods: Vitamin supplement was administered 8 times over a 21-day period, metabolite concentrations were measured until day 269 (e.g. 248 days after the end of vitamin supplementation). Results: From day 0 to 21, the serum levels of the 3 vitamins increased significantly, after cessation of supplementation the levels returned to baseline within the follow-up period. The MMA, 2-MCA and tHcy levels decreased during the treatment period significantly and did not reach baseline values within the 248-day period. Cysta levels did not differ significantly from baseline, either during or after treatment. Conclusion: MMA and 2-MCA levels rather reflect the availability of vitamins, especially cobalamin, than the actual serum levels. Since deficiencies of folate, cobalamin and pyridoxal phosphate in the elderly may cause hyerhomocysteinemia and hence may have unfavorable effects on mental performance, determination of MMA and 2-MCA levels in elderly patients with mental disturbances may be a cost-effective measure to improve or maintain mental performance.