Multivitamins with 0.4 – 0.8 mg of folic acid are best in birth defect prevention

Periconceptional use of folic acid supplements is effective for the primary prevention of neural-tube defects and is recommended by reproductive health researchers

Recent research in this area, however, centres on two main debated questions. The first one is whether the use of folic acid alone or folic acid-containing multivitamins is better. The second one is whether high dose of folic acid (e.g. 5 mg) might be better than a daily multivitamin with low dose 0.4 – 0.8 mg of folic acid. This paper by Prof. Andrew E. Czeizel, receiver of 2002 award of US National Council on Folic Acid for Excellence in Research in the Field of Folic Acid and Birth Defects Prevention, presents a comparison of study of two intervention trials and a case-control surveillance of congenital abnormalities that involve very large population.

The first intervention trial is a randomized controlled trial involving 2,819 participants supplemented with multivitamins containing 0.8 mg of folic acid, and 2,683 unsupplemented participants. And the second intervention trial is a two-cohort controlled trial involving 3,069 participants supplemented with the same multivitamins, and 3,069 unsupplemented participants. The case-control surveillance of congenital abnormalities includes 30,054 pregnant women who received high dose (in general 6 mg) of folic acid supplementation – in a much larger racially homogeneous European-Caucasican population.

The pooled findings of these trials indicate that approximately 92% of neural-tube defects may be prevented by the supplemented multivitamins containing 0.8 mg of folic acid. A comparison of these results shows that multivitamins containing 0.8 mg of folic acid were more effective for the reduction of neural-tube defects than high dose of folic acid. Both multivitamins and folic acid can prevent some part of congenital cardiovascular malformations. Only multivitamins were able to reduce the prevalence at birth of obstructive defects of urinary tract, limb deficiencies and congenital pyloric stenosis, while folic acid was effective in preventing some part of rectal/anal stenosis/atresia, and high dose of folic acid had effect in preventing some orofacial clefts. In a separated study, Smithells et al. used a multivitamin containing 0.36 mg of folic acid and they were able to prevent 91% of recurrent neural-tube defects. In light of these findings, it is recommended the daily use of multivitamin supplement including 0.4 – 0.8 mg of folic acid for pregnant women to prevent neural-tube defects and some other congenital abnormalities.