Supplementation is probably the most efficient method for ensuring individual protection against an NTD pregnancy but not for a general public health strategy. The disappointing results of supplementation programs led experts to consider fortification of foodstuffs as another public health strategy. There are two approaches to food fortification— voluntary and mandatory. In the former, it is left to individual manufacturers to add folic acid to specific products, whereas in mandatory fortification the relevant authority, with government approval and legislation, requires that a specified dietary staple or staples be fortified to a specified agreed level. The objective of a food fortification policy to prevent NTDs is to increase folate intakes for the target childbearing population as near as possible to the recommended intakes while maintaining safe levels of intake for the entire population. The United States first introduced mandatory food fortification. The Food and Drug Administration (FDA) authorized the addition of folic acid to enriched grain products in 1996 and made compliance mandatory by January 1998. The FDA decided on a level of fortification of 140 mg of folic acid per 100 g flour, and this was estimated to increase average daily intakes of folic acid by 100 mg in women of reproductive age. Studies of fortified foods in the United States have found considerably higher folate levels for many products than those required by the regulations, and the actual average daily increase is estimated to be 150-200 mg. The Canadian government introduced a similar fortification plan in 1998. Studies in both countries have shown that the markers of body folate status (serum and red cell folate and serum homocysteine) have increased dramatically in the population postfortification.
The effect on NTD rates has been striking, especially in Canada. Comparing NTD rates before and after fortification showed decreases of 55% in Nova Scotia and 49% in Ontario postfortification. A study in the United States reported a decrease of 19% in the NTD rate after fortification, and the smaller decrease was considered to be mainly due to the fact that pregnancy terminations for NTDs were not included in the US data and were included in the Canadian studies. These studies provide strong evidence of the effectiveness of mandatory food fortification of folic acid in preventing NTDs and point the way forward for other countries interested in solving this problem.
Fortification of flour was introduced in Chile in 2000 at a level of 220 mg folic acid per 100 g flour. Approximately 38 countries currently either fortify flour (including the United States, Canada, Chile, Argentina, and Israel) or have agreed to do so. In the United Kingdom, the government nutritional advisory committee (the Committee on Medical Aspects of Food and Nutrition Policy) recommended fortification at the level of 240 mg of folic acid per 100 grams of flour, but the Board of the Food Standards Agency decided to defer its implementation. No European Union country has decided to fortify flour to date.
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