© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: The rate of neural tube defects (NTDs) in Europe has remained similar since the 1990s despite folic acid supplement recommendations (400 µg/day) for women of childbearing age. Mandatory folic acid fortification of staple foods has proved effective for reducing the prevalence of NTDs in over 80 countries. This study estimated the impact of addition of folic acid to bread or flour in the Republic of Ireland on reducing the risk of occurrence of NTD-affected pregnancies and the possible risk of masking (undiagnosed) vitamin B12 deficiency in older adults. Methods: Analyses were based on the Irish National Adult Nutrition Survey (2008–2010). Folic acid fortification was modelled using DaDiet© software. Estimates were made of the increase in average daily folic acid intake in women (18–50 years) and the risk of exceeding the tolerable upper intake level (UL) of 1000 µg for folic acid in adults over 50 years of age. Results: The fortification scenarios examined would reduce the risk of NTD-affected pregnancies by 8–32%, corresponding to an increase of 39–152 µg in the mean daily folic acid intake of WCBA. The risk of masking anaemia associated with vitamin B12 deficiency in older adults would be negligible as the probability of exceeding the UL for folic acid, even by a small amount, is very low (= 0.2%). Conclusions: These levels of addition of folic acid to bread or flour would effectively reduce the risk of NTDs while allowing safe consumption of folic acid at current levels from other fortified foods and supplements.