Methylenetetrahydrofolate reductase 677C-T genotype modulates homocysteine responses to a folate-rich diet or a low-dose folic acid supplement
I know this is quite a title to swallow, but this enzyme is quite well studied and can have an incredible impact across a wide range of disease states. Remember the folate needs to be converted to its active form (tetrahydrofolate) to be used by the body. The enzyme that works in this process is subject to genetic variation and those with the homozygous (sluggish copies from both parents) genotype have a much increased risk for high homocysteine, neural tube defects, certain cancers, Alzheimers, etc… The patients with the sluggish enzymes can override this slow enzyme with high levels of substrate (i.e. folate supplementation).