Prevalence of low folate deficiency after wheat flour supplementation – should we still measure serum folate?

OBJECTIVES: To determine the frequency of folic acid deficiency in consecutive serum folate determinations and to determine whether there was a significant decrease in serum folate deficiency after folate was added to wheat flour. METHODS: A retrospective descriptive observational study was performed of consecutive folate measurements at the Hospital Privado Universitario, Cordoba, Argentina. RESULTS: Two cohorts were analyzed: 1197 folate measurements between 2001 and 2008 (before supplementation) and 3335 folate measurements from 2009 to 2014 (after supplementation). Folate deficiency was found in 84/1197 (7%) subjects in the pre-supplementation group and in 58/3335 (1.73%) after supplementation. The prevalence of folate deficiency was 12% between 2001 and 2003 when folate was not added to flour compared to 4% in 2004–2007 (p-value < 0.0001) when folate was added to the flour but no widespread use was documented. CONCLUSIONS: In the studied population, the prevalence of serum folic acid deficiency after folate supplementation was low at 1.73%. There was a significant decrease in folate deficiency after folate was added to wheat flour. Given the low prevalence of folic acid deficiency observed in this and similar studies, and the observed change with supplementation, we conclude that routine measurement of serum folate is of limited clinical use.