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Experts urge addition of folic acid to flour to halt “avoidable tragedy” of birth defects

BMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k477 (Published 31 January 2018) Cite this as: BMJ 2018;360:k477
  1. Gareth Iacobucci
  1. The BMJ

The UK government has been urged to fortify flour with folic acid to prevent birth defects, after a reappraisal of existing evidence concluded that there was “no scientific basis” for setting an upper level of folate intake.

Researchers at Queen Mary University of London and the School of Advanced Study at the University of London concluded that there were “elementary” flaws in a previous analysis from the US Institute of Medicine that suggested that the daily dose of folic acid should not exceed 1 mg.1

Health experts said it would be “an avoidable tragedy” and a “dereliction of public health duty” if the UK government failed to fortify flour on the basis of the fresh evidence. If the UK had adopted the same level of folic acid fortification as had the US in 1998, neural tube defects in an estimated 3000 babies could have been avoided, the authors of the reanalysis calculated.2

Countries that have imposed folate fortification of food products, including bread and cereals, have seen a substantial fall in numbers of babies born with neural tube defects, such as anencephaly and spina bifida. But the UK has not done so because of fears that fortification might push people’s intake of folate over the recommended “upper limit,” after the Institute of Medicine’s analysis found that treating people with vitamin B12 deficiency with increased doses of folic acid might lead to a raised risk of neurological damage.

However, the London team’s reanalysis of the institute’s study found that neurological damage was caused not by folic acid but by failure to treat B12 deficiency with the vitamin itself. The authors concluded that that the institute’s study was “totally flawed” because it had failed to account for denominators as well as numerators when examining studies that looked at whether folic acid could exacerbate the progression of a B12 deficient neuropathy.

The reanalysis found no indication that higher doses of folic acid would increase the risk of B12 neuropathy. They also said there was no basis for the Institute of Medicine’s “arbitrary” recommendation of a maximum intake of 1 mg a day of folate, just as there ws no upper limit for other B vitamins. In the UK white flour is already fortified with iron, calcium, and other B vitamins (niacin and thiamin).

Although women who could become pregnant are advised to start taking a daily folic acid supplement, the authors said that most did not do so. If fortification were introduced in the UK, women would still be advised to take folic acid supplements to achieve a greater level of protection. But the authors emphasised the importance of fortification as “a protective population safety net.”

The lead author of the reanalysis, Nicholas Wald of the Wolfson Institute of Preventive Medicine at Queen Mary, said, “With the upper limit removed there is no scientific or medical reason for delaying the introduction of mandatory folic acid fortification in the UK and other countries that have not yet adopted this proven public health intervention.

“It does seem a tragedy that something that could be so easily and safely prevented leads to terminations and the births of affected individuals. Folic acid is not harmful. Failure to fortify is harmful. It is time for the government to mandate folic acid fortification in the UK.”

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