Reversing Folic Acid Fortification In The Diets Of A Selected Group Of Women

Nutrition Research Newsletter, Sept, 1999 by Geraldine J. Cuskelly, Helene McNulty, John M. Scott

In January 1998, fortification of every 100 g of grain products with 140 [micro]g folic acid became a mandatory policy in the United States. The reasoning behind this policy was the recent influx of evidence that showed that folic acid protects against both recurrence and first occurrence of neural tube defects (NTDs). Four hundred micrograms of folic acid were recommended to prevent first occurrences of NTDs. This new policy was intended to address the prevention of first occurrences, which represent 95% of all NTD cases.

One way of predicting the effectiveness of this new policy is to determine the effect of removing a similar amount of folic acid from the diets of young women who had been electively exposed to chronic fortification. A group of researchers from Northern Ireland's University of Ulster did just this by examining the changes in dietary intakes and in red blood cell (RBC) and serum folate concentrations. This fortification policy could use research in its defense since there has been debate over the safety issues of folate fortification and concern that fortification should be higher to offer protection against NTDs.

Fifty-one women aged 17-40 years were recruited for this study, which was carried out over a 12-week period. Subjects were instructed by a registered dietitian to exclude folic acid-fortified foods from their diets for the 12-week intervention period. The women were given a comprehensive list of foods that were fortified with folic acid in Northern Ireland and foods that could be replaced as substitutes. In the United Kingdom, food fortification with folic acid is conducted on a voluntary basis, unlike the United States. A food frequency questionnaire (FFQ) and the diet history method were used to assess dietary intake at baseline and toward the end of the intervention period. Blood samples were also obtained.

The women were divided into two groups, either consumers or non-consumers of folic acid-fortified foods. Consumers had significantly higher total folate intakes and RBC folate concentrations than non-consumers. However, serum folate concentrations were not significant. After the exclusion period, a significant decrease of mean total folic acid and RBC folate concentrations occurred in consumers, but not in non-consumers.

Cessation of eating folic acid-fortified foods resulted in removing 78 [micro]g folic acid per day from the diet, which is close to the expected effect of 100 [micro]g per day. However, the researchers explain this small discrepancy by suggesting that the study underestimated the effect of fortification on RBC folate concentrations because folic acid will usually be supplied long-term, rather than a 12-week period. They speculate that "this magnitude of change in folate status in women can be anticipated as a result of the new US fortification legislation and is predicted to have a significant, although not optimal, effect in preventing neural tube defects." Because there are people that do not believe that fortification with folic acid is the answer to the NTD problem, efforts should continue to educate women of reproductive age about achieving optimal folate status for the prevention of NTDs.

Geraldine J. Cuskelly, Helene McNulty, and John M. Scott, Fortification with Low Amounts of Folic Acid Makes A Significant Difference in Folate Status in Young Women: Implications for the Prevention of Neural Tube Defects, Am J Clin Nutr, 70(2): 234-239 (August 1999) [Correspondence: H. McNulty, Northern Ireland Centre for Diet and Health, University of Ulster, Coleraine, BT 52 ISA, Northern Ireland, UK. E-mail: H.McNulty@ulst.ac.uk.]