Low vitamin B-12 concentrations in patients without anemia: the effect of folic acid fortification of grain.
BACKGROUND
In some patients with vitamin B-12 deficiency mistakenly treated with folic acid, anemia resolved but neurologic complications became worse (masking). Fortification of enriched cereal grains with folic acid has raised concerns that people who consume large quantities of cereal grains, particularly the elderly, may be at increased risk of masking. It is unclear, however, what proportion of people with low vitamin B-12 concentrations do not have anemia and whether the proportion is increasing.


OBJECTIVE
We investigated whether fortification has increased the proportion of patients with low vitamin B-12 but without anemia.


METHODS
We reviewed the laboratory results of every patient for whom a vitamin B-12 concentration was measured at the Veterans Affairs Medical Center in Washington, DC, between 1992 and 2000. Those with a low vitamin B-12 concentration (< 258 pmol/L) had their hematocrits and mean cell volumes checked. The proportion without anemia was examined by year before, during, and after folic acid fortification began.


RESULTS
There were 1573 subjects with a low vitamin B-12 concentration. The proportion without anemia did not increase significantly from the prefortification period (39.2%) to the period of optional fortification (45.5%) and the postfortification period (37.6%). These findings did not change when the analysis was limited to patients aged > 60 y or when a more conservative definition of low vitamin B-12 (< 150 pmol/L) was used.


CONCLUSIONS
Despite evidence that folic acid exposure has increased dramatically since food fortification began, this population showed no evidence of an increase in low vitamin B-12 concentrations without anemia. If confirmed, these results would indicate that food fortification has not caused a major increase in masking of vitamin B-12 deficiency.
Mills
James L
JL
Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA. jamesmills@nih.gov
Von Kohorn
Isabelle
I
Conley
Mary R
MR
Zeller
Jack A
JA
Cox
Christopher
C
Williamson
Robert E
RE
Dufour
D Robert
DR
D000368:Aged; D000740:Anemia; D002523:Edible Grain; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005527:Food, Fortified; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D014806:Vitamin B 12 Deficiency / Q000453:epidemiology*
D005492:Folic Acid