Abstract:
Bioavailabilityofoxalateishighlyinfluencedbythepresenceofmetalcationsinthegastrointestinaltractasaresultofthedifferentsolubilityofoxalatesalts.BioavailabilityisfurtherinfluencedbypHeffectsonoxalatesolubilityatvariousstagesofdigestion,particularlyatgastricpHatwhichinsolubleoxalatehasbeenfoundtosolubilize.TheaimofthepresentstudywastoassesstheeffectofgastrointestinalpHanddifferentmetalionsontherelativesolubilityofoxalateaftertreatmentwithrelevantgastricandintestinalenzymesinsimulatedgastrointestinaldigestionconditions.Wholebrancerealsandbeanswereusedastestsamples.Oxalatesolubilityincreasedalongwithreproduciblerecoverysuchas97±4atgastricpH-2comparedtohigherpH.Highamountofsolubleoxalate(32±1.2)wasfoundinwheatbranaftersimulatedinvitrodigestionundergastricconditionsascomparedtointestinalconditionsi.e.11±0.5.Theavailabilityofcalciumforabsorptionwasfoundtobeverylowcomparedtothatofmagnesiumandpotassiumi.e.,15±0.3,13±0.5to10±0.42and4±1inwheatbransampleatgastricandintestinalconditionssimultaneously.Theformationofacomplexbetweencalciumandoxalatereducedsolubilityandhencemadecalciumlessavailableforabsorption.Presenceofmetalsandoxalatenotonlyreducesoxalateavailability,butitalsoreducesavailabilityofmetalcations
