Why Vitamin B12 Deficiency Should be on your Radar Screen

<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong>
Risk Factors for
<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong>
“The clinical indications (for cobalamin deficiency) are of
prime importance since routine screening tests, such as
the blood count, are not always abnormal. The same
criteria apply to both sexes and to all age groups,
including preterm infants and children.” Amos, 1994
Patient characteristics that increase the likelihood of a
vitamin <strong>B12</strong> deficiency can <strong>be</strong> divided broadly into
demographic and <strong>be</strong>havioral characteristics that increase
the risk of inadequate dietary intake (malnutrition) and
physiologic factors that increase the risk of
malabsorption. Some factors, such as advanced age,
might increase the risk of both malnutrition and
malabsorption. In the United States, most cases of
vitamin <strong>B12</strong> deficiency are due to malabsorption rather
than inadequate intake. We will review the more obvious
demographic and <strong>be</strong>havioral “red flags” of aging and
strict vegetarianism and vegan diets and then
summarize the less readily apparent but more common
physiologic factors that can affect absorption.
Demographic and Behavioral Risk Factors
The risk of developing a vitamin <strong>B12</strong> deficiency increases
with age.(1, 6, 16, 21-23) The elderly, defined as
individuals 65 years of age or older, are more likely to
develop a vitamin <strong>B12</strong> deficiency <strong>be</strong>cause they are at risk
for both malabsorption and malnutrition. The frail
elderly, especially, might have dietary insufficiency for a
num<strong>be</strong>r of reasons, including cognitive dysfunction,
social isolation, mobility limitations, and poverty.
In contrast to the importance of age, other demographic
characteristics, including sex, race, and ethnicity, are not
as important in predicting vitamin <strong>B12</strong> deficiency. While
several studies have found that mild cobalamin
deficiency is most common among elderly White men
and least common among Black or African-American and
Asian-American women, (2, 3, 16, 24) the differences
20
In the United
States, most cases
of vitamin <strong>B12</strong>
deficiency are due
to malabsorption.