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.