How common is vitamin B12 deficiency?

Authors: Allen, Lindsay - A

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2008
Publication Date: 2/1/2009
Citation: Allen, L.H. 2009. How common is vitamin B12 deficiency? American Journal of Clinical Nutrition. 89:693S-696S.

Interpretive Summary: In the context of considering the vitamin B12 fortification of flour, it is important to know who is at risk of vitamin B12 deficiency and whether they would benefit from flour fortification. This article reviews current knowledge of the prevalence and causes of vitamin B12 deficiency and considers whether fortification would improve the status of deficient subgroups of the population. In large surveys in the USA and United Kingdom, ~6% of those aged =60 y are vitamin B12 deficient (plasma B12 <148 pmol/L), with the prevalence of deficiency increasing with age. Closer to 20% have marginal status (plasma B12 148-221 pmol/L) in later life. In developing countries deficiency is much more common, starting in early life and persisting across the life span. Inadequate intake, due to low consumption of animal source foods, is the main cause of low serum B12 in younger adults and probably in poor populations world-wide; in most studies serum vitamin B12 concentration is correlated with intake of the vitamin. In older persons food-bound cobalamin malabsorption becomes the predominant cause of deficiency, due at least in part to gastric atrophy, but it is likely that most elderly can absorb the vitamin from fortified food. Fortification of flour with vitamin B12 is likely to improve the status of most persons with low stores of the vitamin. However, intervention studies are still needed to assess efficacy and functional benefits of increasing intake of the amounts likely to be consumed in flour, including elderly with varying degrees of gastric atrophy.

Technical Abstract: In considering the vitamin B-12 fortification of flour, it is important to know who is at risk of vitamin B-12 deficiency and whether those individuals would benefit from flour fortification.This article reviews current knowledge of the prevalence and causes of vitamin B-12 deficiency and considers whether fortification would improve the status of deficient subgroups of the population. In large surveys in the United States and the United Kingdom, ~6% of those aged =60 y are vitamin B-12 deficient (plasma vitamin B-12,148 pmol/L), with the prevalence of deficiency increasing with age. Closer to 20% have marginal status (plasma vitamin B-12: 148–221 pmol/L)in later life. In developing countries, deficiency is much more common, starting in early life and persisting across the life span. Inadequate intake, due to low consumption of animal-source foods, is the main cause of low serum vitamin B-12 in younger adults and likely the main cause in poor populations worldwide; in most studies, serum vitamin B-12 concentration is correlated with intake of this vitamin. 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. However, intervention studies are still needed to assess efficacy and functional benefits of increasing intake of the amounts likely to be consumed in flour, including in elderly persons with varying degrees of gastric atrophy.