Future studies should investigate the effect of long-term supplementation of (6S)-5-Methyl-THF-Na versus (6S)-5-Methyl-THF-Ca and folic acid on intracellular folate levels (RBC-folate), biochemical markers (i.e., lowering tHcy), and clinical endpoints such as correction of anemia especially in relation to the presence of polymorphisms in the MTHFR and DHFR genes. The gene discussed is MTHFR; the disease is anemia.