How we wish to be cited:
Sandström H, Norberg B. Folate fortification masks cobalamin deficiency [evaluation].
Rondel 2003; 14. URL: http://www.rondellen.net
Folate fortification masks cobalamin deficiency
Scientific source
I. Johnson MA, Hawthorne NA, Brackett WR, Fischer JG, Gunter EW, Allen RH,
Stabler SP. Hyperhomocysteinemia and vitamin B-12 deficiency in elderly using Title IIIc
nutrition services. Am J Clin Nutr. 2003 Jan;77(1):211-20.
Reviewers
Herbert Sandström, general practitioner and lecturer, Department of Family
Medicine, University of Umeå, and Bo Norberg, The Rondel
E-mail: herbert.sandstrom@fammed.umu.se
Summary
A high prevalence of cobalamin deficiency was found in elderly persons living on a diet
fortified by folate. Cobalamin deficiency was associated with deteriorated
cognition.
Cognition was improved by oral high-dose cobalamin therapy. The results support previous
fear of folate masking of cobalamin deficiency in progress.
Background
In 1998, cereals were fortified with folate in the USA in order to reduce the prevalence
of neural tube defects in newborn infants. There was also a hope that folate fortification
would reduce the incidence of thrombo-embolic vascular events in the population. The
homocysteine levels have decreased in the population after folate fortification. The
incidence of neural tube defects also appears to have been reduced.
Folate masking of cobalamin deficiency
Since folate and cobalamin are joined by a series connection in the metabolism (methionine
cycle) of the human cell ( cf 1,2), many experts feared that folate fortification would
mask a cobalamin deficiency in progress. The legendary Victor Herbert (3) was for example
an outspoken representative of this view. The present study (I) verified a high prevalence
of cobalamin deficiency in elderly persons on folate fortification. It also verified the
efficacy of treating B12 deficiency with oral high-dose cobalamin. Otherwise,
interpretation of the results should be cautious; selection biases and high dropout rates
weaken the values of the study.
Role of spoke-in-the-wheel
An interesting observation is that the present study (I) actualizes the interplay between
micronutrients in deficiency states. Folate fortification preserved a normal hemoglobin
value and a normal erythrocyte size in most participants. However, cobalamin deficiency
was reflected by elevated homocysteine levels. On the other hand, a cobalamin deficiency
with anemia could not be treated successfully in the presence of an iron
deficiency. The
findings correlate closely with clinical experience from 1950 and forward, that the
treatment of an "isolated deficiency" may unmask other incipient deficiencies
(cf 4). Thus, one or two incipient deficiencies may act as spoke in the wheel in any
deficiency treatment.
Conclusion
In folate-fortified elderly persons on nutrition programs, cobalamin deficiency was
prevalent and associated with poor cognition, anemia, and hyperhomocysteinemia.
Herbert Sandström Bo Norberg
References
Published March 26, 2003