Percentage of variation of DNA damage biomarkers, homocysteine and cell growth explained by genotype, folic acid or riboflavin. Percentage variation of micronucleus, nucleoplasmic bridge, nuclear bud frequency, homocysteine concentration and cell growth explained by folic acid or riboflavin concentration or MTHFR C677T genotype. It is evident that folic acid is the dominant variable with respect to DNA damage biomarkers, whilst MTHFR C677T genotype was almost as important as folic acid in explaining the degree of variation for homocysteine and cell growth. Riboflavin only appeared to have some substantial but small effect on the variation of nucleoplasmic bridges and homocysteine. For more details refer to Kimura et al 2004 .