Not all cases of neural-tube defect can be prevented by increasing the intake of XXXX .

@entity1501 @entity1 @entity601
Some countries have introduced mandatory @entity1501 fortification, whereas others support periconceptional supplementation of @entity1 in childbearing age. Several European countries are considering whether to adopt a fortification policy. Projections of the possible beneficial effects of increased @entity1501 intake assume that the measure will result in a considerable @entity601 ( @entity601 ) in the target population. Therefore, the objective of the present study is to evaluate the beneficial effects of different levels of @entity1501 administration on the prevalence of @entity601 . Countries with mandatory fortification achieved a significant increase in @entity1501 intake and a significant decline in the prevalence of @entity601 . This was also true for supplementation trials. However, the prevalence of @entity601 at birth declined to approximately five cases at birth per 10 000 births and seven to eight cases at birth or abortion per 10 000 births. This decline was independent of the amount of @entity1501 administered and apparently reveals a 'floor effect' for @entity1501 -preventable @entity601 . This clearly shows that not all cases of @entity601 are preventable by increasing the @entity1501 intake. The relative decline depends on the initial @entity601 rate. Countries with @entity601 prevalence close to the observed floor may have much smaller reductions in @entity601 rates with @entity1501 fortification. Additionally, potential adverse effects of fortification on other vulnerable population groups have to be seriously considered. Policy decisions concerning national mandatory fortification programmes must take into account realistically projected benefits as well as the evidence of risks to all vulnerable groups.
