Proton-Coupled Folate TransporterFolic AcidPteroylpolyglutamic AcidsIntestinal AbsorptionJejunumReduced Folate Carrier Proteingamma-Glutamyl HydrolaseFolic Acid AntagonistsFolic Acid DeficiencyMalabsorption SyndromesAbsorptionMembrane Transport ProteinsFolate Receptors, GPI-AnchoredFolate Receptor 1