Minerals.docx

Minerals.docx

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Minerals

Minerals

Introduction

Conception:

mineralsarenutritionallyimportantchemicalelementsobtainedfromthemacronutrientsexcludingC,H,N,andO.

Theyareconsideredessential.Iftheirsourceofexposurewereremoved,therewouldbeaconsistentandreproducibleimpairmentofsomephysiologicalactivity.

Inorganicelementalatomsthatareessentialnutrients,butnotchangedbydigestionormetabolism.

Mineralsarefoundinmanydifferentchemicalformsincluding:

complexes,chelatesandfreeions（especiallygroup1and17elements）.

Mineralsareessentiallyindestructiblesincetheyarenotaffectedbyheat,light,oxidizingagentsorextremesinpH.

Classification

MacroorMajorminerals

minerals

钾（K，potassium）钠（Na，sodium）钙（Ca，calcium）磷（P，phosphorus）镁（Mg，magnesium）氯（Cl，chlorine）硫（S，sulfur）

Presentinbodytissuesatconcentrations>0.01%

MicroorTraceminerals（bodyneedsrelativelyless）

iodine碘I、zinc锌Zn、selenium硒Se、copper铜Cu、molybdenum钼Mo、chromium铬Cr、cobalt钴Co、iron铁Femanganese,fluoride,silicon,tin,arsenic,nickel…

Presentinbodytissuesatconcentrations<0.01%

Essentialmicrominerals（8）:

iodine碘I、zinc锌Zn、selenium硒Se、copper铜Cu、molybdenum钼Mo、chromium铬Cr、cobalt钴Co、iron铁Fe

Potentialtoxicmicro-minerals:

铝Al、锡Sn、锂Li、铅Pb、镉Cd、汞Hg、砷As

FunctionofMinerals

1．partoftherigidbodystructureandsoftbodytissue

如钙、磷、镁是骨骼和牙齿的重要成分，磷、硫是构成组织蛋白的成分。

boneisCa3（PO4）2,CaCO3andMg3（PO4）2arethemajoringredientsofbone,teeth;phosphorusandsulfurarethecomponentsofprotein.Softtissueincludesskin,fibroustissues,fat（whichareconnectivetissue）,andmuscles,nervesandbloodvessels（whicharenotconnectivetissue）.

2．partofbodyfluids（fluidsoutsideofcells）;Na+,K+,andCl-（chlorine）arepresentasionsandpreservetheelectrolytebalanceinourbodies.

3．Keepbalanceoffluid’spHvalue

酸性、碱性无机离子的适当配合，加上重碳酸盐和蛋白质的缓冲作用是维持机体酸碱平衡的重要机制。

4．Keepingneuron,musclesexciting

在组织液中的各种无机离子，特别是保持一定比例的钾、钠、镁、钙离子是维持神经、肌肉兴奋性，细胞膜通透性以及所有细胞正常功能的必要条件。

5．Partofimportantphysiologicalbioactivecomponentsinbody

无机元素是构成某些具有特殊生理功能的物质的重要成分。

如血红蛋白和细胞色素系统中的铁，甲状腺素中的碘和谷胱甘肽氧化物酶中的硒。

6.Someparticipatewithenzymesinmetabolicprocesses（cofactors）

无机离子是很多酶系统的活化剂、辅因子或组织成分。

如盐酸之于胃蛋白酶原，氯离子之于唾液淀粉酶，镁离子之于氧化磷酸化的多种酶类，以及很多其他含金属的酶类。

Absorption&RegulationofMinerals

Absorption

Smallintestine&largeintestine

Regulation

Kidneys&smallintestine

Thebioavailabilityofamineralmaybeinfluencedbyavarietyoffactors:

1.Thechemicalformwilldeterminehowreadilyourbodiesabsorbthemineral.Ahighlystablechelateformwouldbepoorlyabsorbedcomparedtofreeionsthatarereadilyabsorbed.Phytate（植酸盐）andoxalate（草酸盐）,foundinsomefoods,reducetheabsorptionofcalcium,ironandzinc.Iodineabsorptionmaybehinderedbynitrates（硝酸盐）.

But,ligands配位体thatformsolublechelateswithmetalswillenhanceabsorption.

Incontrast,ironabsorptionmaybeincreasedwhenvitaminCisconsumedduringthesamemeal.

2.InteractionswithothermineralsInhighconcentrations,somemineralsmayactuallyinhibittheabsorptionofanothermineral.Theabsorptionofironisinhibitedbyhighconcentrationsofcalcium,andtoomuchironitselfmayleadtopoorzincabsorption.

3.Requirement,Theamountofamineralpeopleactuallyabsorbcanvary,andwilldependupontheirownneeds,andhowmuchtheyalreadyhaveofthatnutrientinthebody.

Mineralsarefairlystableinnormalfoodprocessingconditions.

Calcium

Mostabundantmineralinanimaltissues

99%Cainboneandteethskeleton

Ca（PO4）285%;CaCO310%

1%presentinBlood&othertissuesCalledmisciblecalciumpool（混溶钙池）

Lotsoffunctions

Bone，teethstructure

Nervefunction

Musclecontraction

Bloodclotting

Decreasepenetrationofcapillaryvesselandmembrane

FoodSources

1.MilkanddairyproductsHighamountsHighbioavailability（fortifiedwithvitaminD）

2.GreenleafyvegetablesPoorabsorption

3.Fishbones

4.Fortifiedjuice/cereal

CalciumAbsorption

DependentonVitaminD

Cabindingproteininintestinalepithelialcell

Absorptiondependsonneed

Particularlyhighduringgrowth,pregnancyandlactation

Bioavailabilitydecreasedby

Phytates（grains）

Oxalates

Wheatbranhigherfiber

Lowestrogen雌激素levels（postmenopausalwomen）

CalciumRegulation

Threehormonesinvolvedinregulation

1.VitaminD3fromkidney

2.Parathyroidhormone（PTH）fromparathyroidgland

3.Calcitoninfromthyroidgland

PTHandVitaminD3acttoincreaseplasmaCa,whilecalcitoninactstodecreaseplasmaCa

HormonalControlSystems

Maintainingnormalbloodcalciumandphosphorusconcentrationsismanagedthroughtheconcertedactionofthreehormonesthatcontrolfluxesofcalciuminandoutofbloodandextracellularfluid:

Parathyroidhormoneservestoincreasebloodconcentrationsofcalcium.

1.Increasesboneresorptionbyactivatingosteoclasticactivity

2.Increasesrenalcalciumreabsorptionbythedistalrenaltubules

3.Increasestheformationof1,25-dihydrocholecalciferolbyincreasingtheactivityofalpha-hydroxylsinthekidney

VitaminDactsalsotoincreasebloodconcentrationsofcalcium.Itisgeneratedthroughtheactivityofparathyroidhormonewithinthekidney.

1.Enhancescalciumabsorptionfromtheintestine

2.Facilitatescalciumabsorptioninthekidney

3.Increasesbonecalcificationandmineralization

4.Inexcess,mobilizesbonecalciumandphosphate

CalcitoninisahormonethatfunctionstoreducebloodcalciumlevelsCalcitoninisa32aminoacidpolypeptidesecretedbytheparafollicularcellsinthethyroidgland.Ittendstodecreaseserumcalciumconcentrationand,ingeneral,haseffectsoppositetothoseofPTH.

Suppressionofrenaltubularreabsorptionofcalcium.Inotherwords,calcitoninenhancesexcretionofcalciumintourine.

Inhibitionofboneresorption,whichwouldminimizefluxesofcalciumfromboneintoblood.

ResponsestoLowBloodCalcium

Parathyroidhormone（PTH）released

StimulatesconversionofinactiveformofvitaminDtocalcitrol

Increasesinbloodcalcium

Smallintestine

Resorptionatkidneys&blood

CalciumDeficiencies

1.Ricketsingrowingchildren

2.Osteomalacia（osteoporosis）inadult

CalciumandOsteoporosis

Aroundage40,bonebreakdownexceedsformation.

Ideally,wantveryhighbonemasswhenthisbegins.

Byage65,somewomenhavelost50%ofbonemass.

CalciumToxicity

1.About90%ofallhypercalcemiacasesaretheresultofhyperparathyroidism,aconditioninwhichparathyroidhormonesareproducedinexcess.

2.Increasetherisksofkidneystone肾结石

3.Milk-AlkaliSyndrome,MAS（乳碱综合症）:

symptomsincludehypercalcemia（高钙血）、alkalosis（碱中毒）和renaldysfunction（肾功能障碍）。

乳碱综合症是指因长期进食大量牛奶或钙剂，并服用大量可吸收的碱剂引起的高钙血症、碱中毒及不同程度的肾功能损害等一组临床症候群。

过去多发生在消化性溃疡患者的内科治疗中，因治疗方案的改进，如服用不溶性碱性药物，本征现已罕见。

4.Overtakeofcalciumcandisturbtheintakeofotherminerals.Iron,zinic,magnasium,andphosphorus

Phosphorous

人体内第二大元素，在成人体内含量为400-500g左右，占体重1％左右，占体内无机盐总量的1／4

Functions

1.Componentofbone,teethskeleton

2.Componentofprotein,DNAandRNA

3.Vitallyimportantinenergymetabolism

ATP

creatinephosphate磷酸肌酸磷酸肌酸是在肌肉或其他可兴奋性组织（如脑和神经）中的一种高能磷酸化合物，是高能磷酸基的暂时贮存形式，能在肌酸激酶的催化下，将其磷酸基转移到ADP分子中。

当一些ATP用于肌肉收缩，就会产生ADP。

这时，通过肌酸激酶的作用，磷酸肌酸很快供给ADP以磷酸基，从而恢复正常的ATP高水平。

由于肌肉细胞的磷酸肌酸含量是其ATP含量的3～4倍，前者可贮存供短期活动用的、足够的磷酸基团。

在活动后的恢复期中，积累的肌酸又可被ATP磷酸化，重新生成磷酸肌酸，这是同一个酶催化的相反的反应。

因为细胞中没有其他合成和分解磷酸肌酸的代谢途径，此化合物很适合完成这种暂时贮存的功能。

4.Asacoenzymeinmetabolicsystem（TPP,FAD,NAD+）

5.MaintenanceofbloodpH（phosphatebuffer）

Metabolism&RegulationofPhosphorusintheBody

Smallintestine

VitaminD-dependentactivetransport

Simplediffusion

Concentrationscontrolledby:

Calcitriol,PTH,calcitonin

Excretedbykidney

BioavailabilitycouldbeimprovedifphytatePcanbereduced.FermentationofflourcouldreducephytatePcontent.食物中的磷以有机磷和无机磷两种形式存在，有机磷主要是蛋白质和磷脂类，无机磷主要是谷类和蔬菜中以植酸形式存在的磷，不易被人体吸收。

MainsourceofPingrain

Deficienciesinclude

Ricketsorosteomalacia

Pica异食癖（depravedappetite）–chewingofwood,bones

Lowfertilityorgrowth

PhosphorusToxicity

Overtakeofphosphoruscancausehyperphosphatemia高磷血症是慢性肾脏病（CKD）的常见并发症,是肾功能衰竭排磷困难引起继发性甲状旁腺功能亢进、钙磷乘积变化、维生素D代谢障碍

三、钾（potassium）

FunctionsofPotassiumintheBody

1.Fundamentalfornormalnerveandmusclefunctionespeciallycriticalintherightamountforregulatingnervetransmissionsandmusclecontractions,whichinvolvestheinterchangeofpotassiumandsodiuminandoutofnerveandmusclecells

2.Neededformetabolismofcarbohydratesandproteins..EssentialforproteinandnucleicacidsynthesisinvolvedinsynthesisofproteinfromaminoacidsConvertsglucoseintoglycogen（musclefuel）neededformetabolismandstorageofcarbohydratesforuseasenergybythemuscles

3.Regulatesheartfunctionneededforheartfunctionandrhythm,andhelpstreatheartdisorders.adietcomprisinghighpotassiumfoodslowersriskofstrokeandheartattackbyupto40%.

4.Requiredfornormalfluidbalanceactswithsodiumtocontrolthebody'swaterbalance

5.maintainacid/alkalibalancehelpsregulatethebody'selectrolyteandacid-alkaline（pH）balance

6.Reducesbloodpressurehelpsthebodyhandlesodiumandsoreduceriskofhighbloodpressure

7.preventsosteoporosisstudiesalsoshowacorrelationbetweenbonemineraldensityandintakeofpotassium-richfoodsthathelptomaintainthebody'spH（acidalkaline）balancesothatlesscalciumneedstobemobilizedfrombonetodoso,whichpreservesbonestrengthandpreventsosteoporosis.

8Importantroleinkidneyfunctionpotassiumcitrateisknowntodissolvecalciumandsohelppreventformationofkidneystonesandcalcificationofsofttissues.largescalestudieshaveshownthatthosewhofollowtheRDAandt