Dietary intake of cobalamin in elderly people who have abnormal serum cobalamin, methylmalonic acid and homocysteine levels

Abstract

Objective: To determine if poor dietary intake can explain the cobalamin-related abnormalities often seen in the elderly.

Design: Prospective laboratory survey with a follow-up dietary assessment.

Setting: Social centers for the elderly and an outpatient clinic.

Subjects: Ninety-five free-living subjects >60 y old with abnormal or suspicious findings in cobalamin-related tests and 78 subjects >60 y old with normal results.

Interventions: Serum cobalamin, methylmalonic acid and homocysteine determinations to assess cobalamin status and a one year food-frequency questionnaire to assess cobalamin intake.

Results: Only three of the 173 subjects (1.7%), one of whom had normal cobalamin status, ingested <2 μg cobalamin/d, the Recommended Daily Allowance. Sixty-nine subjects (39.9%) ingested <6 μg/d, but they did not have more abnormal serum cobalamin or metabolite values than those ingesting >6 μg. Ordering all subjects by quintiles according to cobalamin intake revealed no significant trends or differences in any of the serum values either. Moreover, arranging subjects by results of tests of cobalamin status showed that the subjects with abnormal cobalamin status did not differ in cobalamin intake from those with normal cobalamin status, although they did differ in use of supplements. Finally, cobalamin intake, with or without supplements, did not correlate with serum cobalamin or metabolite levels. The absence of any association between cobalamin status and intake contrasts sharply with the significant correlation between folate intake and folate status (P=0.0001).

Conclusions: The high frequency of mildly abnormal cobalamin status in the elderly cannot be attributed to poor intake of cobalamin. Nondietary explanations, such as malabsorption and other phenomena, must always be sought to explain mild cobalamin deficiency in the elderly.

Sponsorship: This study was supported by grants DK 32640 and HL 52234 from the National Institutes of Health and by the NIH National Center for Research Resources of the GCRC grant MO1 RR-43. Computational assistance was provided by the NIH NCRR GCRC MO1 RR-43 CDMAS project.