To investigate the association between serum unmetabolized folic acid (UMFA) concentrations and folic acid from fortified foods and nutrients known as dietary methyl-group donors (folate, methionine, choline, betaine and vitamins B2, B6 and B12) in participants exposed to mandatory fortification of wheat and maize flours with folic acid.
Cross-sectional study carried out with 78 healthy Brazilian participants, both sexes, supplement nonusers. Serum folate, UMFA, vitamin B12 and total plasma homocysteine (tHcy) were biochemically measured. Dietary intake was assessed by two non-consecutive 24-hour dietary recalls (24-HRs) and deattenuated energy-adjusted nutrient data were used for statistical analysis.
Fifty three (67.9%) participants were women. Median (interquartile range) age was 31.5 (27.0 – 44.2) years. Elevated serum folate concentrations (>45 nmol/L) were found in 8 (10.3%), while folate deficiency (<7nmol/L) in 7 (9%) participants. No one had vitamin B12 deficiency (<148 pmol/L). An elevated serum UMFA concentration was defined as >1.10 nmol/L (90th percentile). UMFA concentrations were positively correlated with folic acid intake and negatively correlated to choline, methionine and vitamin B6 intakes. Participants in the lowest quartile of UMFA concentrations had higher total folate (DFEs), natural food folate, methionine, choline, vitamins B2 and B6 intakes than participants in the highest quartile. Folic acid intake (ß = 0.004; P = 0.001) and age (ß = 0.010; P = <0.001) were determinants for UMFA concentrations
UMFA concentrations were directly influenced by folic acid intake from fortified foods in a healthy convenience sample of the adult Brazilians exposed to mandatory flour fortification with folic acid.