Independent effect of vitamin B₁₂ deficiency on hematological status in older Chinese vegetarian women

Abstract

We have examined the independent effect of vitamin B₁₂ deficiency on hematological indices in older Chinese vegetarian women using a cross-sectional study design: 119 women older than 55 years who had been vegetarian for more than 3 years were studied. Fasting blood samples were taken for complete blood count, serum iron, total serum iron binding capacity, serum iron saturation, serum vitamin B₁₂, serum folate, serum methylmalonic acid levels (MMA), and renal function test. Subjects with iron deficiency (iron saturation <15%) and those with serum creatinine >150 mmol/L were excluded. The prevalence of definite vitamin B₁₂ deficiency (vitamin B₁₂ level < 150 pmol/L and MMA ≥ 0.4 μmol/L) was 42%. Another 32.8% had possible vitamin B₁₂ deficiency (either criterion). The prevalence of iron deficiency was 10%. After exclusions, 96 subjects were further analyzed. Vitamin B₁₂ deficiency defined by serum vitamin B₁₂ and MMA was associated with a decrease in hemoglobin concentrations by up to 0.9 g/dL, but it was not associated with an increase in mean corpuscular volume (MCV). Serum MMA but not vitamin B₁₂ levels correlated inversely with hemoglobin and platelet counts and positively with MCV, after adjustment of confounding factors. However, the percentage of subjects with anemia did not increase significantly until serum MMA became >1.0 μmol/L. In conclusion, vitamin B₁₂ deficiency was associated with a significant decrease in hemoglobin concentration. However, anemia associated with vitamin B₁₂ deficiency was seldom macrocytic. We recommend that older vegetarians should be given vitamin B₁₂ supplements routinely. Am. J. Hematol. 70:186–190, 2002. © 2002 Wiley-Liss, Inc.