folytate

Folytate is a term sometimes used to refer to folates, the group of compounds derived from folic acid (vitamin B9) that function as nutrients in humans. Folates are essential for one-carbon metabolism and are required for DNA synthesis, repair, and methylation reactions.

Chemically, folates are pteroate derivatives with one or more glutamate residues (polyglutamates). In foods, folates exist mainly as polyglutamates; during digestion, they are deconjugated and absorbed as monoglutamates; inside cells they may be polyglutamated again for retention and function.

Absorption and transport: In the intestine, enzymes convert polyglutamates to monoglutamates; uptake occurs via proton-coupled folate transporter (PCFT) and reduced folate carrier (RFC); in plasma, mainly 5-methyltetrahydrofolate (5-MTHF) bound to albumin circulates. Cells take up folate via RFC or folate receptors and then add glutamate residues to form polyglutamates again, aiding retention and intracellular work.

Biological role: Folates act as coenzymes in one-carbon transfer reactions, essential for thymidylate and purine synthesis. They donate formyl, methyl, and methylene groups and participate in homocysteine remethylation to methionine, making them crucial for DNA synthesis, repair, and cellular methylation.

Dietary sources and deficiency: Folates are abundant in leafy greens, legumes, and citrus fruits, as well as in fortified foods. Folate deficiency can cause megaloblastic anemia and, during early pregnancy, neural tube defects. Excessive folate intake can mask vitamin B12 deficiency. Some antifolate medications, such as methotrexate, inhibit folate metabolism.