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Wolfson Institute of Preventive Medicine
Barts & London Queen Mary School of Medicine & Dentistry
Charterhouse Square
London EC1M 6BQ
United Kingdom
E-mail: n.j.wald{at}qmul.ac.uk
Royal Free Hospital
London
United Kingdom
Dear Sir:
We believe that Clarke and Grimley Evans (1) are incorrect in 3 important ways when they argue against the immediate introduction of universal fortification of flour with folic acid to prevent neural tube defects in the United Kingdom.
First, there is no evidence that fortification at the level recommended by the Committee on Medical Aspects of Food and Nutrition Policy (COMA) will mask the diagnosis of vitamin B-12 deficiency. Clarke and Grimley Evans overlook recent evidence indicating that folic acid fortification in the United States has not altered the presentation of vitamin B-12 deficiency (2). Their arguments, which suggest that vitamin B-12 neuropathy will increase after folic acid fortification, are therefore without foundation and are not supported by any evidence. In maintaining their proposition of masking, they are preventing the introduction of a beneficial public health measure without good reason or justification.
Second, Clarke and Grimley Evans are incorrect in stating that the UK COMA recommendation that flour in the United Kingdom should be fortified with folic acid at the level of 240 µg/100 g flour was conditional on fortification being set at a minimal level so that the level could never be exceeded—a totally impractical condition—or that fortification be delayed until a "means be instituted to identify and protect elderly persons who are vitamin deficient." Two of us (NJW and AVH) were members of the COMA working group and we are surprised at the statement by Clarke and Grimley Evans because Grimley Evans was himself Chairman of the Working Group that produced the report. A review of the report confirms that although these issues were considered, the recommendation for folic acid fortification was not made conditional.
Third, Clarke and Grimley Evans are incorrect in advising against folic acid fortification until a screening program for vitamin B-12 deficiency is introduced. Vitamin B-12 deficiency may be a public health problem, although this needs to be assessed by determining the incidence of the clinical disease it causes rather than by determining the prevalence of serum vitamin B-12 concentrations below specified cutoffs or the prevalence of homocysteine concentrations above specified cutoffs. The public health solution to any vitamin B-12 deficiency problem is to directly address the problem and not to use it to stop the remedy of another public health problem (neural tube defects) that can be substantially prevented through folic acid fortification. Screening for vitamin B-12 deficiency, which they propose, would be costly and probably of limited efficacy because few screening programs achieve 100% coverage. A preferred solution to vitamin B-12 deficiency in the elderly would be to fortify the diet with vitamin B-12. However, this issue should be separate from the issue of food fortification with folic acid. Whatever is done about vitamin B-12 deficiency, this should not be a reason for failing to prevent neural tube defects through folic acid fortification—a policy that has been accepted by 38 countries throughout the world. One public health measure should not hold up another.
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