Fig. 1

Flow diagram for the selection of participants and the analysis of samples. aSelf-reported change in use of dietary supplements containing folic acid or vitamin B12. bSerum levels of folate or vitamin B12 and plasma levels of homocysteine. Abbreviations: CRP C-reactive protein, MTHFR methylenetetrahydrofolate reductase, SNP single nucleotide polymorphism, SWAN subset-quantile within array normalization