Benefits and risks of fortifying flour with folic acid to reduce the risk of neural tube defects a systematic review
Mandatory fortification of flour with folic acid (140-160 micrograms per 100 grams) in Sweden would probably reduce the number of NTD pregnancies. However, it is not possible to determine with any degree of assurance how large the decrease would be. The main reason is uncertainty about the number of...
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| Format: | eBook |
| Language: | English |
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Stockholm, Sweden
Swedish Council on Health Technology Assessment
2007, October 2007
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| Series: | SBU yellow report
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| Online Access: | |
| Collection: | National Center for Biotechnology Information - Collection details see MPG.ReNa |
| Summary: | Mandatory fortification of flour with folic acid (140-160 micrograms per 100 grams) in Sweden would probably reduce the number of NTD pregnancies. However, it is not possible to determine with any degree of assurance how large the decrease would be. The main reason is uncertainty about the number of pregnancies in Sweden and elsewhere that are currently terminated with the indication of NTDs. Assuming for the sake of argument that the reduction would be 25%, foetuses with NTDs would decrease from 100 to 75, late terminations would decrease from 80 to 56, and newborns with NTDs would decrease from 20-25 to 15-20 Due to uncertainty about the extent to which pregnancies that are terminated due to diagnosed NTDs are under-reported in both Sweden and countries from which the results of fortification are available, promising how much NTDs can decrease in Sweden is not deemed reasonable. The results concerning the association between folic acid intake and the risk of twin pregnancy are conflicting (contradictory scientific evidence). The results that have been presented on the effects of fortifying flour do not indicate that the incidence of twin births would increase. However, data from randomised controlled trials suggest a possible increase. If so, larger doses of folic acid would be involved than have been of interest for fortification so far. The results of a large prospective cohort study, which administered the same dose as two of the controlled trials and controlled well for potential sources of error, do not support the hypothesis that dietary supplements with folic acid increase the risk of twin birth. The results of five observational studies, four of which were based on self-reported intake of tablets containing folic acid and one of which concerned dietary intake of folate, are conflicting. Folates play an important role in cell production and may theoretically be expected to stimulate growth of existing tumours, as well as possibly accelerate the transformation of precancerous stages to active malignancy. Some animal experimental studies support that hypothesis, and a few studies suggest an association between high folate levels and colorectal cancer. Addressing such questions was not the objective of a systematic literature search for this report. The primary objective of the project was to systematically examine the scientific evidence for the benefits and risks of fortifying flour with folic acid. Benefits refer to the possibility that the incidence of neural tube defects (NTDs) is lower with fortification than without fortification. Risks refer to the possibility that a higher intake of folic acid increases the likelihood of twin pregnancy. Other possible effects of fortification were not included in the examination. The main conclusion of the Swedish Council on Technology Assessment in Health Care is that mandatory fortification of flour with folic acid cannot be unequivocally recommended based on the scientific evidence in this report.1. An overall assessment indicates that fortification reduces the incidence of NTDs (moderately strong scientific evidence). |
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| Physical Description: | 1 PDF file (18 pages) illustrations |
| ISBN: | 9879185413157 |