Relationship between Sources of Dietary Fiber Intake and Homocysteine Metabolism in Relation to Serum Homocysteine Concentrations

While homocysteine is produced as an intermediate metabolite during methionine metabolism, increased blood homocysteine levels are associated with various diseases. In a previous cross-sectional study, we reported a significant negative association between the serum concentrations of homocysteine in 227 young women and their dietary fiber intake. In the present study, we examined the relationship between dietary fiber intake from food sources and serum levels of homocysteine and its metabolites. Homocysteine and its metabolites 5-methyltetrahydrofolate (5MTHF), cystathionine, glycine, methionine, and S-adenosyl-methionine were measured using LC-MS/MS. The soluble, insoluble, and total fiber intake from fruits and mushrooms was significantly inversely correlated with the homocysteine concentrations. Furthermore, the soluble, insoluble, and total fiber intake from fruits was significantly positively associated with the serum 5MTHF concentrations, while the fiber intake from mushrooms was positively correlated with the cystathionine concentration and negatively correlated with the methionine and glycine concentrations. These results suggest that ingesting dietary fiber in the form of fruits and mushrooms maintains a low concentration of homocysteine by activating two different homocysteine-scavenging metabolic pathways.