Effects of Folic Acid-Fortified Milk Consumption on Serum Folate Levels in Japanese Female Students: a Randomized Controlled Trial Stratified by Methylenetetrahydrofolate Reductase C677T Genetic Polymorphism

Abstract

Objective: We studied effects of fermented milk fortified with 200 μg of folic acid (FF milk) on serum folate levels in Japanese women university students. Methods: Adopting FF milk as intervention factor, a randomized controlled trial stratified by MTHFR genetic polymorphism C677T was conducted in 143 university women students. Experimental group subjects were requested to consume FF milk for 4 weeks; control group subjects to consume usual meals. Dietary surveys were conducted using an FFQ, and serum folate concentrations were analyzed utilizing chemiluminescence immunoassay. Using oral mucous membranes, MTHFR genotypes were determined employing PCR-RFLP. Paired ttest, one-way ANOVA, Pearson correlation coefficient, Chi-square test, or Fisher’s exact probability test was adequately applied. Results: MTHFR genotype frequencies were CC type 36 (25%), CT type 75 (52.4%) and TT type 32 (22.4%) as a whole. The subjects were randomly stratified into 73 experimental group (CC type 16, CT type 41, TT type 16) and, 70 control group (CC type 20, CT type 34, TT type 16). Average of folate consumption was 246 μg/day. Average serum folate level was 9.8 ng/mL with statistically significant difference by MTHFR genotype (CC type>CT type>TT type). Serum folate concentrations in the experimental group increased by 1.5 on average after intervention. At baseline, there were 19 subjects having serum folate levels lower than the reference value of NTDs (7 ng/mL): CC type 1/36, CT type 10/75 and TT type 8/32 with statistical difference by MTHFR genotype. In the experimental group those subjects decreased from 10 to 2 (CT type 1 and TT type 1) after intervention. Conclusions: Serum folate levels increased in the experimental group subjects after intervention, suggesting consumption of the FF milk sufficiently elevated serum folate concentrations for prevention of NTDs, irrespectively of MTHFR genotypes.