Methyltetrahydrofolate is the active form of folate, a B-vitamin that is crucial for various bodily functions, including DNA synthesis, repair, and methylation. Folate, in its inactive forms (such as folic acid), requires conversion in the body to become usable. MTHF directly participates in the methylation of homocysteine to methionine, an essential amino acid that contributes to protein synthesis and various metabolic processes.