How often does a B12 deficiency occur?
A B12 deficiency occurs much more frequently than generally assumed. People often mistakenly think that a deficiency only occurs in sufferers of pernicious anemia or strict vegetarians. There are, however, many more causes of a deficiency. There is also the widely held misconception that a B12 deficiency is always associated with anemia, which often causes doctors to miss the diagnosis.
In international scientific literature a deficiency is defined by a total serum value of < 148 pmol/L and a marginal status exists when this value is < 221 pmol/L. The marginal status too can prove to be problematic to diagnose.
Research (National Health and Nutrition Examination Surveys, 1999-2001) provides the following figures:
A blood value of < 148 pmol/L (deficient):
20-39 years old: less than or equal to 3%
40-59 years old: circa 4%
70 years and older: circa 6%
A marginal status: < 221 pmol/L :
20-59 years old: circa 14-16%
> 60 years and older: more than 20%
The Framingham Offspring Study
The Framingham Offspring Study, a large ongoing study in the United States of 5135 persons, produced the following figures:
Less than 9% of the people between 26 and 83 years of age was B12 deficient( <148 pmol/L and 16% had a value of <185 pmol/L despite the high average intake of 9 milligram per day. (DV= 2.4 milligram per day)
A survey of B12 values under 3766 children from 4 days to 19 years old showed three children to have a value of less than 74pmol/L, which is 1 out of 1255, and 18 children had a value lower than 148pmol/L, 1 out of 112. The lowest values were found in white children between 12 and 19 years old. However, this is based on reference values that are not adjusted for age. If age is taken into account, B12 deficiency is much more frequent.
B12 deficiency is much more prevalent than assumed. A conservative estimate based on the figures from various surveys would amount to 3 to 5% of the total population. For the Netherlands that would be over half a million people.
Deficiencies are not exclusively frequent with seniors, for regularly we see deficiencies in youths and children. The reference values should actually be adjusted for age because of the lowering of B12 values over the course of life. If this were properly done, it would become clear that B12 deficiency occurs very frequently. This is often disregarded which causes late diagnosis and treatment with potentially serious consequences.
- How common is vitamin B12 deficiency? Lindsay H Allen Am J Clin Nutr 2009;89(suppl):693S-6S
- Cobalamin Status and Its Biochemical Markers Methylmalonic Acid and Homocysteine in different Age Groups from 4 Days to 19 Years. Anne-Lise Bjørke Monsen, Helga Refsum, Trond Markestad, and Per Magne Ueland, Clinical Chemistry 49:12 2067–2075 (2003)