Bioavailability of folic acid and L‐5‐methyltetrahydrofolic acid in fortified bread: a randomized placebo‐controlled trial

Abstract

Folic acid fortification has been introduced in several countries to reduce the incidence of neural tube defects. However, it could mask the hematologic signs of vitamin B12 deficiency. L‐5‐methyltetrahydrofolic acid (MTHF), which is unlikely to mask vitamin B12 deficiency, may be a safer fortificant, but is not stable in most food matrices. Microencapsulation of MTHF with antioxidant sodium ascorbate is an effective means of preventing loss during baking and storage. The aim of the study was to investigate the bioavailability of microencapsulated MTHF in bread in a 16‐wk, double‐blind, randomized placebo trial. Healthy volunteers 18–45 y (n=45) were randomly assigned to bread containing MTHF (452 μg), folic acid (400 μg) or placebo. Fasting blood was analyzed for red cell and plasma folate concentrations at baseline, 8, and 16 wks. At 16 wk, after adjustment for baseline concentrations, mean (95% CI) red cell folate was 572 (341, 804) and 428 (200, 656) nmol/L higher in the MTHF (P<0.001) and folic acid (P=0.002) groups, respectively, than in the placebo group. Mean plasma folate was 28 (15, 41) and 26 (13, 39) nmol/L higher in the MTHF (P<0.001) and folic acid (P=0.01) groups, respectively, than in the placebo group. In conclusion, bread fortified with MTHF was at least as effective as folic acid in raising red cell and plasma folate concentrations in this population. (Supported by the Advanced Food Materials Network)