Elsevier

The Lancet

Volume 367, Issue 9519, 22–28 April 2006, Pages 1352-1361
The Lancet

Review
Folic acid: a public-health challenge

https://doi.org/10.1016/S0140-6736(06)68582-6Get rights and content

Summary

Despite worldwide public-health campaigns recommending periconceptional daily supplementation of synthetic folic acid to reduce the risk of neural tube defects, many women are not following these recommendations. At the same time, in most European countries no decline in defects has been recorded in recent years. Vulnerable groups are those with a low standard of education, young people, and women with unplanned pregnancies. Furthermore, in most countries without mandatory fortification, the general population is not consuming the recommended 0·4 mg of food folate per day. Voluntary fortification improves the situation, but does not reach all parts of the population. In the USA, Canada, and Chile, mandatory fortification of flour substantially improved folate and homocysteine status, and neural tube defects rates fell by between 31% and 78%. Nevertheless, many countries do not choose mandatory folic acid fortification, in part because expected additional health benefits are not yet scientifically proven in clinical trials, in part because of feared health risks, and because of the issue of freedom of choice. Thus, additional creative public-health approaches need to be developed to prevent neural tube defects and improve the folate status of the general population.

Section snippets

Effect of folic acid on risk of anomalies and disease

Two of the most common serious birth defects of the brain and spine are spina bifida and anencephaly. These neural tube defects occur when part of the neural tube, which later develops into spinal cord and brain, does not close. Closing normally happens around 24 days after conception—ie, before the woman has realised that she is pregnant. In the case of anencephaly all infants are stillborn or die shortly after birth, whereas in the case of spina bifida, children survive with lifelong

Recommendations

The evidence of the benefit of folic acid in prevention of neural tube defects has since 1992, led many health organisations to issue recommendations for women to maintain a healthy diet and take folic acid supplements (0·4 mg daily; to prevent neural tube defect recurrence: 4 mg daily) when planning a pregnancy or throughout childbearing age.28, 40 These recommendations might differ slightly: in Australia, for example, 0·5 mg folic acid daily is recommended.41 However, 0·4 mg per day was the

Safety of folic acid

Despite the noted beneficial effects of folic acid fortification on folate status and neural tube defects in countries that implemented either mandatory or voluntary fortification in addition to the promotion of supplement use, concern continues that folic acid might also have adverse effects.35 Although folate is safe and almost free of toxicity,108 concerns that folic acid fortification could mask symptoms of vitamin B12 deficiency and precipitate neurological complications have been raised.1

Public health implications

Despite public-health campaigns, knowledge about the proper periconceptional time to use folic acid supplements for the prevention of neural tube defects is not widespread in women and only a maximum of half of them are following the recommendations. Vulnerable groups are people of low educational status, young people, immigrants, and women with unplanned pregnancies. A substantial percentage of women still choose not to take the supplements even though they are aware of the beneficial effects.

Conclusions

In countries choosing mandatory fortification with folic acid, careful assessment of beneficial as well as potential negative health effects is of prime importance. In countries deciding against mandatory fortification, promotion and funding of research on additional effective means to improve folic acid supplement use is essential. At present, there exist only a few new strategies, which are not yet part of comprehensive folic acid campaigns worldwide. Thus, not only careful monitoring and

Search strategy and selection criteria

This review is a non-systematic overview of articles published in English, German or French over the past decade. Thus, main emphasis is placed on results from western countries. Several earlier, commonly referenced, key publications are also cited. Unpublished findings presented in press releases were not considered. Articles were selected from the personal bibliographic databases of the authors and from a MEDLINE search with more than 40 key words including “folic acid”, neural tube

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