Print Email Facebook Twitter The Binding of Folic Acid and 5-Methyltetrahydrofolate to Folate-Binding Proteins during Gastric Passage Differs in a Dynamic in Vitro Gastrointestinal Model Title The Binding of Folic Acid and 5-Methyltetrahydrofolate to Folate-Binding Proteins during Gastric Passage Differs in a Dynamic in Vitro Gastrointestinal Model Author Verwei, M. Arkbåge, K. Mocking, H. Havenaar, R. Groten, J. TNO Voeding Publication year 2004 Abstract Despite its low natural folate concentration, milk is responsible for 10-15% of the daily folate intake in countries with a high dairy consumption. Milk products can be considered as a potential matrix for folate fortification, e.g., with synthetic folic acid, to enhance the daily intake of folate. In untreated milk, the natural folate, 5-methyltetrahydrofolate (5-CH 3-H4folate), is bound to folate-binding proteins (FBP). In this study, the extent of binding to FBP for folic acid and 5-CH 3-H4 folate was investigated in a dynamic in vitro model simulating human gastric passage. Protein binding of folic acid and 5-CH 3-H4 folate was characterized using gel-exclusion chromatography. Before gastric passage, folic acid and 5-CH3-H 4 folate were bound mainly to FBP (76-79%), whereas 7% was free. Folic acid remained bound to FBP to a similar extent after gastric passage. For 5-CH3-H4 folate, the FBP-bound fraction gradually decreased from 79 to 5% and the free fraction increased from 7 to 93%. Although folic acid enters the proximal part of the intestine bound to FBP, 5-CH 3-H4 folate appears to be present mainly as free folate in the duodenal lumen. The stability of FBP was similar in both folate/FBP mixtures, i.e., 70% of the initial FBP content was retained after gastric passage. This study indicated that FBP are partly stable during gastric passage but have different binding characteristics for folic acid and 5-CH 3-H4 folate in the duodenal lumen. This could result in different bioavailability from folic acid- and 5-CH3-H4 folate-fortified milk products. Subject BiologyPhysiological Sciences5-MethyltetrahydrofolateFolate-binding proteinFolic acidGastric passageMilk products5 methyltetrahydrofolic acidfolate binding proteinfolic acidabsorptionarticledairy productduodenumdynamicsfood intakegastrointestinal tractin vitro studymilk levelmodelnonhumanprotein bindingsimulationvitamin supplementationAnimalsCarrier ProteinsChromatography, GelDuodenumFolic AcidFood, FortifiedGastrointestinal TransitHumansMilkMilk ProteinsModels, BiologicalProtein BindingReceptors, Cell SurfaceTetrahydrofolates To reference this document use: http://resolver.tudelft.nl/uuid:af96db46-bc71-4ab0-bc4c-95a03855c54a TNO identifier 237570 ISSN 0022-3166 Source Journal of Nutrition, 134 (1), 31-37 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.