The appropriate dose of folic acid in relation to mandatory food fortification and supplementation programs continues to be debated. The data from the Dublin study, which showed a marked relationship between early pregnancy maternal RCF levels and NTD risk, were used to examine the effectiveness of a food fortification intervention to increase maternal folate levels to prevent NTDs. The analysis showed that if, as a result of food fortification, all women in a population doubled their RCF level, the prevalence of folate-responsive NTDs would be reduced by 66%. If this increase were 150%, which could be achievable with sufficient fortification, the level of protection would be 73% of folate-respon-sive NTDs (equivalent to 53% of all NTDs). The finding that a woman's risk of having an NTD pregnancy is related to her early pregnancy levels of RCF in a continuous dose-response relationship suggested that folic acid intake is also related to risk in a continuous dose-response-type relationship, and this was demonstrated in a randomised trial that studied the effect of three different doses of folic acid on RCF levels and reduction in NTD risk. The results of this study in women of reproductive age showed that an extra 0.1, 0.2, or
0.4 mg daily during a 6-month period would be expected to reduce NTD rates by 22, 41, and 47%, respectively. According to another dose-response model that examined the effect of increases in a wide range of daily folic acid intakes on NTD prevention, a 5.0 mg daily dose of folic acid was estimated to decrease NTD risk by 85% in women with a presupplementation serum folate level of 5 ng per liter. These authors argue that the current recommended daily dose of 0.4 mg for folic acid supplements is too low and should be increased to 5.0 mg. They also argue, somewhat controversially, that no known or suspected adverse effects of the 5.0 mg dose have been recorded.
The 4.0 mg daily supplement recommended internationally by National Departments of Health for the prevention of NTD recurrence is based mainly on the unequivocal evidence of the efficacy of this dose in the UK Medical Research Council Trial. In another large nonrandomized intervention study, a daily dose of 0.36 mg folic acid seemed to offer similar protection because the recurrence rate in the treated groups was similar to that in the Medical Research Council trial. So while the recommendation of 4.0 mg to prevent recurrence is quite correctly based on the best scientific evidence, it is likely that a much smaller dose would be equally effective.
Was this article helpful?
A Hard Hitting, Powerhouse E-book That Is Guaranteed To Change The Way You Look At Your Health And Wellness... Forever. Everything You Know About Health And Wellness Is Going To Change, Discover How You Can Enjoy Great Health Without Going Through Extreme Workouts Or Horrendous Diets.