Assessment of the potential effect of incremental increases in folic acid intake on neural tube defects in Australia and New Zealand

Objective: To estimate the number of neural tube defects that could be prevented in Australia and New Zealand by increasing levels of folic acid intake. Methods: Available data on prevalence of neural tube defects in Australia and New Zealand, folic acid supplement use and serum folate were used in a published model to estimate the number of neural tube defects that could be prevented in Australia and New Zealand for increments of folic acid intake from 0.1 mg daily to 1 mg daily. Results: An increase of 0.2 mg folic acid per day was estimated to result in the prevention of 49 (95% Cl 27-84) neural tube defects per year in Australia and 11 (95% Cl 6-18) in New Zealand. A separate estimation for Indigenous Australians found that 0.2mg of folic acid daily could prevent 7 (95% Cl 4-11) neural tube defects in Indigenous infants per year. Conclusions: These data should be useful in considering primary preventive strategies for neural tube defects, including the possible introduction of mandatory fortification of food with folic acid. The estimates are imprecise because of limitations in the data used in the model. Implications: More representative and precise data on neural tube defects, serum folate levels and use of folic acid supplements from all Australian States and New Zealand are needed to refine the output from the model and to provide a baseline assessment of folate status against which to measure the effects of any future interventions to prevent neural tube defects.