RESUMO
OBJECTIVE: To determine the impact that mandatory fortification with folic acid of wheat flour used in breadmaking has had on the blood folate levels of an Australian population since it was introduced in September 2009. DESIGN, SETTING AND PATIENTS: A retrospective analysis of serum and red blood cell (RBC) folate levels of 20,592 blood samples collected between April 2007 and April 2010 from a wide variety of inpatients and outpatients and analysed in a large public hospital diagnostic pathology laboratory. MAIN OUTCOME MEASURES: Prevalences of low levels of serum and RBC folate and monthly mean levels before and after introduction of mandatory fortification. RESULTS: Between April 2009 and April 2010, there was a 77% reduction in the prevalence of low serum folate levels (from 9.3% to 2.1%) in all samples tested and an 85% reduction in the prevalence of low RBC folate levels (from 3.4% to 0.5%). In April 2010, the prevalence of low RBC folate levels for females of childbearing age was 0.16% for all samples. There was a 31% increase in mean serum folate level (from 17.7 nmol/L to 23.1 nmol/L; t = 9.3, P < 0.01), and a 22% increase in mean RBC folate level (from 881 nmol/L to 1071 nmol/L). The greatest increment in mean serum folate levels occurred in September 2009, the month that mandatory fortification was introduced, although there was evidence of a gradual change during the preceding months. CONCLUSION: The introduction of mandatory fortification with folic acid has significantly reduced the prevalence of folate deficiency in Australia, including in women of childbearing age.