The effect of vitamin B12 deficiency on older veterans and its relationship to health.

OBJECTIVE: To examine the effect of vitamin B12 deficiency on older veterans and its relationship to general health and cognitive impairment.
DESIGN: Cross-sectional study.
SETTING: Oklahoma City Veterans Affairs Medical Center. PARTICIPANTS: Data for this research were obtained from 303 ambulatory, older veterans who used the outpatient laboratories of the Oklahoma City Department of Veterans Affairs Medical Center. Subjects were included in the study if they were 65 years of age and older and if they had no known diagnosis associated with B12 deficiency. The sample in this study consisted of 301 men and 2 women aged 65 to 89 years. MEASUREMENTS: This study used two separate measurements of vitamin B12 deficiency: (1) a strict definition of B12 deficiency (serum B12 level < laboratory norm) and (2) a broader definition of B12 deficiency (serum B12 level < laboratory norm or laboratory norm < B12 < 300 pg/mL and methyl malonic acid (MMA) or homocysteine (HC) elevated by more than two standard deviations). The laboratory norm is 200 pg/mL. The dependent variables were measures of cognitive impairment and general health. Cognitive impairment was measured using the Folstein Mini-Mental State Examination (MMSE) and general health was measured using the RAND 36-Item Health Survey Version 1.0. The control variables for this study were the subjects' daily alcohol intake, daily intake of a vitamin/mineral supplement, annual income, and level of education. RESULTS/
CONCLUSIONS: Nineteen subjects (6%) were vitamin B12-deficient as measured by the strict definition of B12 deficiency (serum B12 level < laboratory norm), and 49 subjects (16%) were vitamin B12-deficient as measured by the broader definition of B12 deficiency (serum B12 level < laboratory norm or laboratory norm < B12 < 300 pg/mL and MMA or HC elevated by more than two standard deviations). Vitamin B12 level decreases as age increases. Of the nine general health outcomes measured by using the RAND 36-Item Health Survey, only bodily pain is associated with vitamin B12 deficiency, and only then when B12 deficiency is measured as serum B12 level < laboratory norm, the strict definition of B12 deficiency. Vitamin B12-deficient subjects experience more bodily pain than those with normal vitamin B12 levels. There is a significant difference between B12-deficient subjects and B12 normal subjects on cognitive impairment, with B12 normal subjects indicating less cognitive impairment, only when B12 deficiency is measured as B12 level < laboratory norm, the strict definition of B12 deficiency. The broader measurement of vitamin B12 deficiency (i.e., serum B12 level < laboratory norm or laboratory norm < B12 < 300 pg/mL and MMA or HC elevated by more than two standard deviations) is not a significant correlate of cognitive impairment and general health.