Prevalence of vitamin B-12 deficiency

 Since fortification of flour with folic acid started 10 years ago in the US, efforts have been taken to fortifying flour with vitamin B-12.

So, how prevalent is B-12 deficiency?

• In the US and UK, about 6% of those older than 59 years are vitamin B-12 deficient (vitamin B-12 blood levels less 148 pmol/L).
• The prevalence of B-12 deficiency increases with age.
• Close to 20% have marginal status (vitamin B-12 blood levels between 148–221 pmol/L) in later life.
• In developing countries, a B-12 deficiency is more common — starting in early life and persisting throughout life.

The bottom line?
Inadequate intake, due to low consumption of animal-source foods, is the main cause of low vitamin B-12 blood levels in younger adults and probably the main cause among the poor, worldwide.

In older persons, food-bound cobalamin malabsorption becomes the predominant cause of deficiency, at least in part due to gastric atrophy, but it is likely that most elderly can absorb the vitamin from fortified food.

Fortification of flour with vitamin B-12 is likely to improve the status of most persons with low stores of this vitamin.

What isn’t known is the effect of B-12-fortified floor on neural tube defect pregnancies, as was the case with folic acid, the practical effect of B-12-fortified flour on elderly individuals with a B-12 deficiency, and its potential side effects (macrocytic anemia and neurological complications).

The American Journal of Clinical Nutrition has published a supplement on this topic.
1/19/09 19:57 JR