The body’s conversion of synthetic, inactive folic acid is a multi-step biochemical process that occurs in the intestines and liver. In the presence of intestinal or liver dysfunction this conversion may not be sufficient to meet the body’s needs. Furthermore, up to 60 percent of the Canadian population may have a genetic enzyme defect that makes it difficult for them to convert folic acid into active 5-MTHF. For these individuals and many others, 5-MTHF supplementation may be a more effective method of folate repletion. In concert with vitamin B12, 5-MTHF functions as a methyl-group donor involved in the conversion of the amino acid homocysteine to methionine. Methyl-group donation is vital to many biochemical processes, including the synthesis of serotonin, melatonin, and DNA. 5-MTHF is also involved in production of the catecholamine neurotransmitters (dopamine, norepinephrine, epinephrine) and the production of beneficial nitric oxide in vascular endothelial cells, which promotes healthy blood vessel function.