A controlled field trial is needed

Thirty three years ago Hibbard and Smithells linked folate deficiency in pregnancy with neural tube defects.1 Smithells then led a series of observational and intervention studies which showed that improving folic acid status early in the pregnancy of mothers who had previously had a child with neural tube defects reduced the recurrence in that pregnancy.2 A randomised trial by Britain's Medical Research Council confirmed that finding3 and a Hungarian trial showed a reduction in the first occurrence too. 4 To reach almost all women in the very early stages of pregnancy, when few would be sure they were pregnant, folic acid fortification of a staple food has been advocated, and a Department of Health committee has now recommended universal fortification of flour in the United Kingdom. Though the benefits are clear, the possible harms of such a policy are not. We need to be cautious in implementing a universal policy.

After the initial British and Hungarian studies several others gave mostly similar results. 5 6 As a result a campaign led by the Health Education Authority in the UK aimed to improve folate status from before conception to 12 weeks of pregnancy by increasing folic acid intake from foods and supplements. A third of …