Minerals in nutrition.pdf

Explains the minerals in our day to day life, their absortion, food sources, RDA, deficiency and toxicity.

1. MINERALS IN NUTRITION
Dr. R Baburaj

2. MINERALS
Mineralsaretheinorganicelements,otherthan
carbon,hydrogen,oxygenandnitrogen,which
remainbehindintheashwhenfoodisincinerated.
Theyareusuallydividedintotwogroups–
macromineralsandmicrominerals(ortrace
elements)
Themineralsareclassifiedaseitheressentialor
non-essential,dependingonwhetherornottheyare
requiredforhumannutritionandhavemetabolic
rolesinthebody.

3. MINERALS
Non-essentialelementsarealsocategorised
aseithertoxicornon-toxic
Essential in the diet
◦Major minerals
more than 100mg/day needed
◦Trace minerals
less than 100mg/day needed

4. MINERALS

5. MINERALS: FUNCTIONS
Minerals function mainly in three ways in the body:
1.Asstructuralcomponents,e.g.calcium,phosphate
andmagnesiuminbonesandteeth
2.Inorganiccombinationsasphysiologicallyimportant
compounds,e.g.phosphorusinnucelotides,zinc
inenzymessuchascarbonicanhydrase,iodinein
thyroidhormone
3.InsolutioninbodyfluidstomaintainpH,help
conductnerveimpulses,controlmusclecontraction,
e.g.sodiumandpotassiuminbloodandintracellular
fluids
Themacromineralsaremainlyinvolvedinfunctions1
and3,andthemicromineralsinfunction2

6. MINERALS FUNCTIONS

7. MINERALS ABSORPTION
Anormaldiet,composedofamixtureofboth
plantandanimalfoodstuffs,shouldsupplyall
themineralsrequiredbythebody.
Whensuchadietisnotavailable,orinsome
othersituations,itmaybenecessaryto
providethemissingelementsintheformof
supplementsorbyfortifyingthedietwith
additionalminerals.
Themineralsingestedinfoodareabsorbed
afterdigestionfromthegutintotheblood
stream,whichtransportsthemtothesites
wheretheyfunctionorarestored.

8. MINERALS ABSORPTION
Notallmineralsareabsorbedtothesame
extent.Some,includingsodiumand
potassium,arereadilyabsorbedasionsor
assimplecompounds.
Others,suchascalcium,magnesiumand
phosphorusmaybecombinedasindigestible
orinsolublecompoundsinfoodandareless
easilytakenupfromthegut.
Afewothers,especiallysomeofthetrace
elementssuchasiron,arepoorlyabsorbed.

9. MINERALS ABSORPTION
Uptakeofcertainmineralsfromfoodcanbe
affectedbyothercomponentsofthediet.Thus
phyticacidandphytatesincerealscaninhibit
absorptionofironandzinc.
Thesameeffectcanbecausedbyoxalateincertain
vegetables.
Iodineabsorptioncanbelimitedbysulphur-
containingcompoundsknownasgoitrogens,which
occurincertainplants,suchassomebrassicaeand
cassava.

10. MINERALS -HEALTH IMPLICATIONS
Ifanessentialelementisatalowlevelinthediet,a
nutritionaldeficiencymayoccur,withspecific
symptoms.
Thusaninadequateintakeofironcancauseanaemia
whenthereisinsufficienthaemoglobintomeetthe
needsofthebodyforoxygentransport.
Adeficiencyofiodinecanleadtogoitrewhenthe
bodytriestocompensateforalowproductionof
theiodine-containingthyroidhormonebyincreasing
thesizeofthethyroidgland.

11. MINERALS -HEALTH IMPLICATIONS
Inadequatezincmayresultingrowthfailurein
children.
Usuallytheseconditionsarecorrectedwhen
intakeofthemissingelementisincreasedby
improvingthedietorbyproviding
Supplements
Anexcessiveintakeofamineralmayalsohave
seriousconsequencesforhealth
Toomuchsodiuminthedietmaybe
associatedwithhighbloodpressureand
increasedriskofastroke.

12. MINERALS -HEALTH IMPLICATIONS
Aconditionknownassiderosis,inwhichan
excessofironisdepositedinthebody,can
resultwhentoomuchironisabsorbed.
Selenosis,asometimesfataleffectofan
excessiveintakeofseleniumisknownto
occurinpartsofChinawherehighlevelsof
theelemententerlocallygrownfoodsfrom
selenium-richsoil.
Lessseriouseffects,suchasnausea,canbe
causedbyahighintakeofzinc.

14. MINERALS –DIETARY SOURCES
Somefoodsourcesarebetterthanothersas
sourcesofminerals
Plantfoodsaregenerallypoorinironandzinc,with
theexceptionofcertaindarkgreenvegetablessuch
asspinach
Dairyproductsaregenerallyanexcellentsourceof
calcium
Redmeatandoffal,suchasliver,arethebestdietary
sourcesofeasilyabsorbediron
Manyofthetraceelementsarefoundinrelatively
highconcentrationsinfishandotherseafoods

15. Sources of minerals in the food guide
pyramid

17. MINERALS –SUPPLEMENTS
Formanypeoplesupplementsareanimportantsourceof
minerals
Mineralsupplementsareavailableinanumberofchemical
forms,eitherasinorganiccompounds,suchasferrous
sulphateandcalciumcarbonate,orasorganic
preparationssuchasseleniumyeastandzinc
gluconate
Theproductsvaryintheamountsofthedifferentelements
theycontain,intheirabsorbabilityandinotherqualities
andwhileundoubtedlytheirusecanmakeadefinite
contributioninsomecasestonutritionalhealth,therecan
alsobeproblemssuchasover-dosingandinteractionswith
othercomponentsofthediet

18. MINERALS –SUPPLEMENTS
The addition of minerals and other nutrients to
foods to increase their nutritional value is widely
practiced.
Inthe1920siodisedsaltwasintroducedtohelp
combatendemicgoitre.
Iodisedsalt,aswellasotheriodisedfoodssuchas
breadandmonosodiumglutamate,aretodaywidely
usedinpartsoftheworldwhereiodinedeficiency
diseases(IDD)arestillendemic,suchasIndia,and
China,PapuaNewGuinea,CentralAfricaandthe
AndeanregionofSouthAmerica.

19. CALCIUM
Withoutanadequatesupplyofthemacromineralcalciumin
thedietcalcificationoftheskeletonwillbeadverselyaffected
Duringearlygrowthanddevelopmentthesupplyofcalcium
forthispurposeisparticularlycriticalandforthisreasonthe
amountrequiredbyachildisproportionallygreaterthanfor
anadult(BritishNutritionFoundation,1989)
Calcium-RDI
Adults 1000mg/day
Pregnantwomen 1000mg/day
Lactatingwomen 1000mg/day
Post-menopausalwomen 1300mg/day

20. CALCIUM ABSORPTION
Uptakeofcalciumfromfoodinthegutis
notveryefficient.
Onlyabout30%isabsorbed,with70%
lostinfaeces.
Absorptionisacomplexprocess,which
isunderthecontrolofthe
cholecalciferol(vitaminD)-parathyroid
hormonesystem.

21. CALCIUM ABSORPTION
Calciumistransportedacrosstheintestinal
mucosaboundtoaspecialcarrierprotein.
Synthesisofthisproteinisstimulatedbyan
activatedformofcholecalciferol,1,25-
dihydroxycholecalciferol(1,25-DHCC).
IfvitaminDlevelsarelow,calcium
absorptionwillberestrictedandadeficiency
willoccur.
Tobeabsorbed,calciummustbeinthe
solubleionicform.

22. CALCIUM ABSORPTION
Severalfoodcomponentscanpreventthis
happening.
Theseincludephyticacid(inositol
hexaphosphate)incereals,andoxalatein
certaindarkgreenvegetables,suchasspinach,
andinrhubarb.
Uronicacidindietaryfibrecanhavea
similareffect,ascanfreefattyacidsand
certainotherdietaryfactors,includingsodium
chlorideandahighproteinintake.

23. Calcium
Factors that
enhance absorption
Stomach acid
Vitamin D
Lactose
Growth hormones
Factors that inhibit
absorption
Lack of stomach acid
Vitamin D deficiency
High phosphorus intake
High-fiber diet
Phytatesin seeds, nuts, and
grains
Oxalatesin beet greens,
rhubarb, and spinach

24. Cauliflower, watercress,
brussels sprouts, rutabaga,
kale, mustard greens, bok
choy, broccoli, turnip greens
≥ 50%
absorbed
≈ 30%
absorbed
Milk, calcium-fortified soy
milk, calcium-set tofu, cheese,
yogurt, calcium-fortified
foods and beverages
≈ 20%
absorbed
Almonds, sesame seeds,
pinto beans, sweet potatoes
≤ 5%
absorbed
Spinach, rhubarb, Swiss
chard
Bioavailability of Calcium from
selected sources

25. WeaverCMandPlaweckiKL,1994Dietarycalcium:adequacyofa
vegetariandiet.AJCN59(suppl):1238-1241S
1 cup =240ml
Cow’s milk
168 g
Calcium equivalents
7 ¾ Cups
2 ½ Cups
7 Cups2 slices
1 tub

26. Functions of calcium in the body
Over99%ofbodycalciumisintheskeleton,
whereitbothprovidesstructuralsupportand
servesasareservoirformaintainingplasma
levels.
Calciuminplasmaplaysanumberofroles,for
exampleinmusclecontraction,neuromuscular
functionandbloodcoagulation.
Tomaintaintheseroles,calciumlevelsinthe
plasmamustbeverystable.

27. © 2008 Thomson -Wadsworth

28. OSTEOPOROSIS
Osteoporosisisaconditionwhichischaracterised
bylossofbonetissuefromtheskeletonand
deteriorationofbonestructurewithenhancedbone
fragilityandincreasedriskoffracture.
Itisrelativelycommonintheelderly,especially
females,butmayalsooccurintheyoung
Thehigherrateinwomenseemstobeassociated
withanumberoffactors:
thelowerskeletalmassinwomencomparedto
men,
agreaterrateofcalciumlossand
Afallinoestrogenproductionwithage.

29. IRON
Ironisthesecondmostabundantmetalintheearth’scrust,
ironinsufficiencyisprobablythemostcommonnutritional
deficiencyintheworld.
Evenamongtheinhabitantsofwell-feddevelopedcountriesit
continuestobecommon,especiallyinwomen
Ironisanessentialnutrientforalllivingorganisms,with
theexceptionofcertainbacteria.
Ithastwomajorrolesinhumanphysiology.
Asacomponentofhaemo-Mineralsglobin,theredpigment
ofbloodandmyoglobininmuscle,ironatomscombine
reversiblywithoxygentoactasitscarrierfromthelungsto
thetissues.

30. IRON ABSORPTION
Theuptakeofironisacomplexandhighly
regulatedoperation.
Oncetheelementisabsorbedfromtheintestine
intotheblood,onlysmallamountsarelostfromthe
body,exceptwhenbleedingoccurs.
Thereisnophysiologicalmechanismforsecretion
ofiron,soironhomeostasisdependsonits
absorption.
Thusthehealthyindividualwithagoodstoreof
ironisabletomaintainabalancebetweenthesmall
normallossesandtheamountsoftheelement
absorbedfromfood.

31. IRON ABSORPTION
Themetalfirstenterstheintestinalmucosalcells
whereitisboundintoferritin,aniron-storage
protein.Thisisalargemoleculefromwhichtheiron
canbereadilymobilisedwhenrequired.
Someoftheincomingironmaybetransferred
directlybyatransportprotein,transferrin,tobone
marrowandothertissuestobeusedinthesynthesis
ofhaemoglobinandmyoglobin.

32. IRON ABSORPTION
Ironabsorptionisapparentlyregulatedby
theexistingironstatusofthebody.
Ifthisislow,theabsorptionmechanismcan
bestimulatedtoincreasedactivity.
Whenironstoresarehigh,absorptionis
sloweddown.
Thereisevidencethatothermineral
elements,suchaszinc,cancompetewith
ironfortheactiveabsorptionpathway.

33. IRON ABSORPTION
Severalotherdietaryfactorscanaffect
absorption,includingphytateandfibre,
whichinhibitabsorption,andascorbic
acidandprotein,whichincreaseuptake.
ThepHofthegutalsohasaneffect,with
foodironmainlyinthemorereadily
absorbedferrousstateunderacid
conditions.

34. best = heme iron
(animal sources of iron)
~25% absorbed
poor = non-haem iron
(vegetative sources)
~17% absorbed

35. If the body
does not
need iron
Iron is not absorbed and is
excreted in shed intestinal cells
instead. Thus, iron absorption
is reduced when the body does
not need iron.
If the body
needs iron
Mucosal cells in the
intestine store excess
iron in mucosal ferritin
(a storage protein).
Iron in food
Mucosal ferritin releases iron to
mucosal transferrin (a transport
protein), which hands off iron to
another transferrin that travels
through the blood to the rest of
the body.

36. Iron absorption from foods

37. Iron
Absorption-enhancing Factors
MFP factor (MFP factor is a peptide found
in meat, fish and poultry) enhances the
absorption of nonhemeiron.
When nonhemeiron is consumed with
vitamin Cat the same meal,
absorption of iron increases.
Citric acid and lactic acid from foods,
HClfrom the stomach, and sugars
enhance nonhemeiron absorption

38. Iron
Absorption-inhibiting Factors
Phytatesand fibers from legumes,
grains, and rice
Vegetable proteins in soybeans,
legumes, and nuts
Calcium in milk
Tannic acid and other polyphenols in
tea, coffee, grains, oregano, and red
wine

39. IRON FUNCTION
oxygentransport
cellular electron transfer (energy production)
Inavarietyofenzymes,suchasthe
cytochromes,ironatoms,presentinthe
ferrousandferricstates,interchangewith
gainorlossofanelectron,aspartofthe
electronchainresponsiblefortheredox
reactionsnecessaryforreleaseofenergyin
cellularcatabolismandthesynthesisoflarge
molecules.

40. IRON FUNCTION
Immunesystem
Inadditiontoitsmajorfunctionsinoxygen
transportandasacofactorinmanyenzymes,
ironalsoplaysanimportantroleinthe
immunesystem.Althoughthemechanisms
involvedarecomplex,thereisgoodevidence
thatanabnormalironnutritionalstatus
canleadtoimpairedimmunefunction,
withseriousconsequencesforhealth
Braindevelopment

41. IRON DEFICIENCY
Iron deficiency anaemia
Irondeficiencyultimatelyresultsinfailureof
thebodytoproducenewbloodcellsto
replacethosethatareconstantlybeing
destroyedattheendoftheirnormal120-day
lifespan.
Graduallythenumberofbloodcellsfallsand,
withthis,theamountofhaemoglobininthe
blood.Thecellsbecomepalerincolourand
smallerinsize.

42. IRON DEFICIENCY
Iron deficiency anaemia
Theseundersizedcellsareunabletocarrysufficient
oxygentomeettheneedsoftissues,soenergy
releaseishindered.Thisiswhatisknowntechnically
asmicrocytichypochromicanaemia,or,simply,
asirondeficiencyanaemia(IDA).
Becausethefallinredbloodcellsoccursgradually,
IDAcanexistforaconsiderabletimebeforeitis
clearlydetected.
Bythenironstoreshavesufferedacriticalfalland
thepersonaffectedshowssymptomsofchronic
tiredness,persistentheadache,and,inmany
cases,arapidheartrateonexertion.

43. IRON DEFICIENCY
Iron deficiency anaemia
Theremayalsobeotherfunctionalconsequencesof
irondeficiency,includingadecreasedworkcapacity,a
fallinintellectualperformance,andareductionin
immunefunction.
Thereistodaygrowingconcernatthepossibility
thatirondeficiencyininfancyandchildhoodcanhave
seriousconsequences,suchasmorbidityinthe
newborn,defectsingrowthanddevelopmentof
infantsandimpairededucationalperformancein
schoolchildren.

44. Iron -RDI
Adults
males 8 mg/day
females 18 mg/day
◦pregnant women 27 mg/day
◦lactating women 9 mg/day
Vegetarians need 1.8
times as much iron
because of low
bioavailability

45. Zinc
Zincdeficiencyinhumansonlybegantobe
recognisedinthe1960s,whenzinc-responsive
dwarfismwasdetectedinchildreninEgypt
Todayzincisknowntobeakeynutrientof
world-widesignificance,andhasjoinediodine
andironamongtraceelementswhose
deficiencyproblemsurgentlyneedtobe
addressed

46. Zinc function
Zincisanessentialcomponentofmore
than200enzymesinthelivingworld,of
whichasmanyas50playimportantmetabolic
rolesinanimals.Itoccursinallsixclassesof
enzymes.
Inaddition,themetalprovidesstructural
integrityinmanyproteins.Zincligands
helpmaintainthestructureofcellmembranes
andofsomeionchannels.

47. Zinc function
Zincfingerprotein’isinvolvedinprocessesof
transcriptionfactorsthatlinkwiththedouble
helixofDNAtoinitiategeneexpression
Theexpressionofcertaingenesisknownto
beregulatedbythequantityofzincabsorbed
fromthediet.
Itisalsobelievedthatzinchasanintracellular
rolethatincludesregulationofcellgrowth
anddifferentiation.

48. Zinc Deficiency
Clinicalsignsseeninpersonssufferingfrommarginal
zincdeficiencyincludedepressedimmunity,impaired
tasteandsmell,nightblindness,impairedmemory,
anddecreasedspermatogenesisinmen
Severezincdeficiencyischaracterisedbyseverely
depressedimmunefunction,frequentinfections,
bulbouspustulardermatitis,diarrhoea,alopeciaand
mentaldisturbances
Aninadequateintakeofzincretardsgrowth&can
resultinstunting,dwarfism,failuretomature
sexually.

49. Zinc absorption from food
Anadulthumancontainsbetween1.5and2.5grams
ofzinc,almostasmuchasironandmorethan200
timestheamountofcopperwhichisthethirdmost
abundanttraceelementinthebody
Absorptionfromthediet,whichoccursinthesmall
intestine,isaffectedbyanumberoffactors.Uptake
hasbeenreportedtorangefromlessthan10to
morethan90%,withanaverageof20–30.
Variouscomponentsofthedietcanaffectuptake.
Competitionforabsorptionoccursbetweenzincand
otherelements,especiallycopper,ironandcadmium.

50. Zinc absorption from food
Phytate,fibre,andcalciumcanlimit
gastrointestinaluptake,whereasanimalprotein
enhancesit.
Adietrichinwholemealbread,forinstance,
whichcontainsthesethreeantagonists,has
beenshowntocausedeficiencyofthe
element.
Zincabsorptionisbelievedtoberelatedto
thepresenceofendogenouszincbinding
ligands.Mostofthezincthatisabsorbedfrom
theintestineisfoundintracellularly,primarily
inmuscle,bone,liverandotherorgans.

51. Zinc absorption from food
Zinc in plasma is mainly loosely bound to
albumin and is also transported attached to
transferrin. In the liver it is bound to the low
molecular weight metal-binding protein,
metallothionin.
Most of the body’s zinc reserves turn over
slowly and are not readily available for
metabolism.
About 10% makes up a readily available pool,
which is used to maintain various zinc-
dependent metabolic functions.

52. Zinc levels in foods and dietary intakes
InWesternsocietiesupwardsof70%of
zincconsumedisprovidedbyanimal
products,especiallymeat.
Liverandotherorganmeatsare
particularlyrichintheelement,asare
mostseafoods.Anothergoodsourceis
oysterswhichmay,insomecases,contain
asmuchas1000mg/kgofthemetal.

53. Zinc levels in foods and dietary intakes
Otherfoodswhichcontainhighlevelsareseedsand
nuts,aswellaswholegraincereals.However,these
andotherplantfoodsalsocontainphytatethatcan
decreasebioavailabilityoftheelement.
InmanyAsiancountrieszincintakesareparticularly
lowbecauseoftheabsenceofappreciableamounts
ofanimalproductsandthepresenceofphytate-rich
plantfoodsinthecustomarydiet.

54. Zinc levels in foods and dietary intakes
The1989USrecommendationwas
◦15mg/dayforadultmales
◦12mg/dayforwomenuptotheageof
50years
◦anextra16–19mg/dayforlactating
women
◦anadditional15mg/dayallthrough
pregnancy

55. Iodine
Thenon-metallicelementiodineisanessential
nutrientthat,apparently,hasasinglefunctioninthe
bodyasacomponentofthethyroidhormones
thyroxine(T4)andtriiodotyronine(T3)
Thesehormonesarenecessaryforarangeofbody
processes,themostimportantofwhicharethe
controlofmetabolicrate,cellularmetabolism,
growthandneuraldevelopment
ProductionofT4andT3iscontrolledbytissue
demandswhicharemediatedbythesecretionsof
thepituitaryglandandbythesupplyofiodineinthe
diet

56. Iodine Deficiency
Deficiencyofiodinecanresultinanumberof
diseases,rangingfromseverecretinismwith
mentalretardationtobarelyvisible
enlargementofthethyroidgland.
Goitreisthenamegiventoenlargementof
theglandthatoccursasthebodyattemptsto
compensateforareductionofitssupplyof
iodinebyincreasingthesizeofthegland.

57. Iodine Deficiency
Theamountofenlargementisrelatedto
thedegreeofiodinedeficiency.
Itoccursespeciallyinpoorerremote
areaswherethesoilisdepletedofiodine
andthegeneraldietislimitedandlacks
usefulsourcesofthemineral.
Goitrewasonceendemic,beforethe
introductionofiodisedsaltandan
improvementinthegeneraldiet.

58. Iodine levels in foods and dietary intakes
Seafoodisthemajornaturalsourceofiodine
inthediet.Fish,crustaceansand
seaweedsarerichintheelement.
Milkisanothergood,thoughadventitious,
sourceofdietaryiodineasaresultoftheuse
ofiodine-containingchemicalstosterilise
dairyequipment.Thispracticehasnowceased
inmanycountries,withtheresultthatdairy
productsaredecreasinginvalueasasourceof
thenutrient.

59. Iodine levels in foods and dietary intakes
Cereals,vegetablesandmeatare
generallypoorsources.
Iodisedsalt(sodiumchloride)was
introducedinmanycountriesinthemid-
twentiethcenturytocombatendemicgoitre
anditsuseledtoasignificantimprovementin
theiodinenutritionalstatus.
Today,areductionintheavailabilityofiodised
salt,coupledwithanoveralldecreasein
consumptionoftableandcookingsalt,has
resultedinafalliniodineintakes.

60. Iodine levels in foods and dietary intakes
The RDI for iodine 150 µg.
Higherintakesofmorethan1mg/day
maycausetoxicity.
Thiscanbetheresultofexcessiveuseof
iodinesupplementsorofnaturaliodine
richfoods(suchascertainseaweeds
thatcancontainmorethan4mg/kgof
iodine).
Paradoxically,highintakesofiodine
depressthyroidfunctionandproduce
goitreincertainindividuals.

61. Selenium
Themetalloidselenium,althoughoneoftherarestofthe
elements,isanessentialtracenutrientforhumansandall
animals,butnotforplants.
Itsessentialitywasonlyrecognisedinthe1970swhenthe
enzymeglutathioneperoxidasewasshowntobea
selenoprotein.
Previouslytheelementhadbeenknownonlyforitstoxicity.
Selenium,intheformoftheuniqueaminoacid
selenocysteine,istheco-factorinseveralimportant
functionalmetalloproteins.
AtphysiologicalpH,theseleniumintheselenocysteineis
almosttotallyionisedandisanextremelyefficientredox
catalyst.

62. Selenium
Atleast30selenoproteinshavebeenshownto
occurinmammaliancells.Severalofthesehave
beenfullycharacterisedandtheirfunctions
determined.
Onegroup,theglutathioneperoxidases,plays
roleinintracellularantioxidantsystems.
Seleniumisalsoanessentialcofactorinthe
iodothyroninedeiodinases,whichare
enzymesinvolvedinthyroidhormone
metabolism
Anotherimportantselenoenzymeisthioredoxin
reductasewhichhelpstocontrolcellgrowth
anddivision

63. Selenium deficiency
Seleniumdeficiencyisassociatedwithseveral
diseasesofmajoreconomicimportanceinfarm
animals.
Inhumanschroniclowintakeofdietaryseleniumis
responsibleforKeshandisease,asometimesfatal
cardiomyopathywhichoccursespeciallyinchildren
andyoungwomen,aswellasforKashin-Beck
disease,achronicosteoarthropathy,whichalso
affectsmainlychildren
ThesediseasesarefoundinpartsofChinaand
otherareasofCentralAsiawheresoillevelsof
seleniumareverylow.

64. Selenium deficiency
Seleniumdeficiencyisassociatedwithseveraldiseasesof
majoreconomicimportanceinfarmanimals.
Inhumanschroniclowintakeofdietaryseleniumis
responsibleforKeshandisease,asometimesfatal
cardiomyopathywhichoccursespeciallyinchildrenand
youngwomen,aswellasforKashin-Beckdisease,achronic
osteoarthropathy,whichalsoaffectsmainlychildren
ThesediseasesarefoundinpartsofChinaandotherareas
ofCentralAsiawheresoillevelsofseleniumareverylow.

65. Selenium deficiency
Severalotherselenium-responsiveconditions
occurinhumans,includingcardiomyopathiesand
muscularproblemsinpatientsontotalparenteral
nutrition(TPN)ifthereisinadequateseleniumin
thefluid
Normalfunctionofthethyroidglandisalso
dependentonanadequatesupplyoftheelement.
Thereisevidencethatseleniumdeficiencycan
causeawiderangeofotherproblemsincluding
immunodeficiency,increasedsusceptibilityto
variousformsofcancerandtocoronaryarterial
disease.

66. Selenium
Functions:
Component of glutathione peroxidase
◦catalyzes removal of hydrogen peroxide
Component of iodothyronine-5’-deiodinase
◦Converts T
4to T
3
Improves killing ability of neutrophils
◦Reduces the prevalence and severity of
mastitis
GSH = reduced glutathione
GSSG = oxidized glutathione
GSH + H
2O
2 GSSG + H
2O

67. Selenium dietary recommendations
Seleniumhasbeenaddedrelativelyrecentlytothedietary
recommendationsinsomecountriesasevidence
establishingitsimportantroleinhumanhealthhasbecome
officiallyaccepted
TheUKRNIof60mg/dayforadultfemalesand75mg/day
foradultmales,ishigherthanthecurrentUSDietary
ReferenceIntakeof55mg/dayforadults(Instituteof
Medicine,FoodandNutritionBoard,2000).
Itisbelieved,however,bysomehealthexpertsthatthese
intakesareinsufficienttomeethumanneedssincetheydo
nottakeintoconsiderationtheelement’scritically
importantprotectiveroleagainstoxidativedamage.

68. Selenium dietary sources
Selenium is widely distributed, but normally at levels
of less than 1 mg/kg, in most foods
Therichestsourcesareorganmeat,suchas
liver(0.05–1.33mg/kg),musclemeat(0.06–
0.42mg/kg)andfish(0.05–0.54mg/kg)
Thoughcerealscontainonly0.01–0.31mg/kg,cereal
productsmakeamajorcontributiontointake
becauseoftherelativelylargeamountofsuchfoods
consumedinmostdiets.
Anothergoodsourceoftheelementisnuts,
particularlyBrazilnutswhicharetherichestfood
sourceoftheelementknown
Vegetables,fruitanddairyproductsarepoor
sources

69. Selenium toxicity
Seleniumtoxicity,orselenosis,hasbeen
welldocumentedinfarmanimals.Ithas
alsooccurredinhumansinsomeparts
ofChinawhereveryhighlevelsoccurin
thesoil
Therehavealsobeenreportsof
selenosisinindividualswhoconsume
excessiveamountsofselenium
supplements.Thereissomedebate
aboutthelevelsofintakethatwillcause
toxicity

70. Selenium toxicity
Residentsofsomehighsoilareasappearto
havenosymptomsofseleniumtoxicity,
althoughtheyconsumeasmuchas700mg/day.
AccordingtotheEnvironmentalProtection
AgencyintheUS,adailyintakeof5mg/kg
bodyweight(350mgfora70kgadult)isnot
toxic.
IntheUKtherecommendedmaximumsafe
seleniumdailyintakefromallsourcesfor
adultsin6mg/kgbodyweightor450mgforan
adultmaleindividuals

71. Selenium Deficiency & Toxicity
Deficiency
Keshan disease-a cardiomyopathy that
affects children and women of child-bearing
age
Toxicity
◦Garlic-like odor of breath
◦Nausea
◦Vomiting
◦Diarrhea
◦Brittleness of teeth & fingernails

72. Magnesium
Magnesiumwasfirstshowntobean
essentialdietarycomponentforratsin
1932andlaterforhumans.
Thisessentialityisareflectionofthe
rolethatmagnesiumplaysinthe
stabilizationofATPandothermolecules.
Isinvolvedinatleast300enzymicsteps
inintermediarymetabolism,forexample
intheglycolyticcycleconvertingglucose
topyruvate.

73. Magnesium
Magnesiumplaysanimportantrolein
thedevelopmentandmaintenanceof
bone;about60%oftotalbody
magnesiumispresentinbone.
Magnesiumenhancesthecondensation
ofchromatin,andgiventheroleof
chromosomalcondensationinthe
regulationofgeneactivity,magnesium
depletioncouldindirectlyaffectgene
transcription.

74. Magnesium Deficiency & Toxicity
Magnesium deficiency causes:
hypocalcemiaand hypocalciuria
hypokalemiaresulting from excess potassium
excretion and leading to negative potassium
balance
abnormal neuromuscular function.
Adverse effects of excess magnesium intake
(e.g., diarrhea, nausea, abdominal cramping)
have been observed with intakes from
nonfood sources such as various magnesium
salts used for pharmacological purposes.

75. Magnesium-RDA & Dietary Sources
RDAforadultwomenis320mg/day
andforadultmenis420mg/day.
Foodswithahighmagnesium
contentincludewholegrains,
legumes,greenleafyvegetables,and
tofu;meat,fruits,anddairyproducts
haveanintermediatemagnesium
content.
Thepoorestsourcesofmagnesium
arerefinedfoods.

76. Magnesium Content Of Some Foods

77. PHOSPHORUS
Phosphorus(asphosphate)isanessential
constituentofallknownprotoplasmandis
uniformacrossmostplantandanimaltissues.
Structurally,phosphorusoccursas
hydroxyapatiteincalcifiedtissuesandas
phospholipids,whichareamajorcomponent
ofmostbiologicalmembranes,andas
nucleotidesandnucleicacid.

78. PHOSPHORUS
Otherfunctionalrolesofphosphorus
include:
●bufferingofacidoralkaliexcesses,
hencehelpingtomaintainnormalpH
●thetemporarystorageandtransferof
theenergyderivedfrommetabolicfuels
●byphosphorylation,andhence
activationofmanycatalyticproteins.

79. PHOSPHORUS
Theeffectsofhypophosphatemiaincludeanorexia,
anemia,muscleweakness,bonepain,ricketsand
osteomalacia,increasedsusceptibilitytoinfection,
ataxia,confusion,andevendeath.
Phosphorusissoubiquitousinvariousfoodsthat
neartotalstarvationisrequiredtoproducedietary
phosphorusdeficiency.
Toxicityresultsinectopic(metastatic)calcification,
particularlyofthekidney&decreasecalcium
absorptionbycomplexingcalciuminthechyme.

80. PHOSPHORUS
Current RDAs for phosphorus are:
infants 100 mg (first 6 months)
275 mg (7–12 months)
children 460 mg (1–3 years)
500 mg (4–8 years)
1250 mg (9–18 years)
adults 700 mg
pregnant women 1250 mg (<18 years)
700 mg (19–50 years) and
lactating women 1250 mg (<18 years)
700 mg (19–50 years)

81. Key:
Fruits
Milk and milk products
Legumes, nuts, seeds
Meats
Best sources per kcalorie
Breads and cereals
Vegetables
PHOSPHORUS
Protein-rich sources, such as
milk (white), meats (red), and
legumes (brown), provide
abundant phosphorus as well.
RDA
for
adults
Food Serving size (kcalories)
Milligrams
Phosphorus in Selected Foods

82. Sodium
fluid volume regulator, electrolyte balancer
Source-mostly in processed foods
Deficiency-must be replaced with water if
blood sodium drops
Toxicity-edema and hypertension
diet moderate in sodium is recommended

83. Chloride
essential nutrient
fluid and electrolyte balance
abundant in foods (especially processed)
◦part of sodium chloride
rarely lacking
dehydration due to water deficiency
Dietary Requirement: Average requirements
for sodium and chloride are estimated to be
about 500 and 750 mg/day, respectively.

84. Potassium
maintaining fluid and electrolyte balance
◦affects homeostasis, such as a steady heartbeat
found in both plant and animal cells
◦found less in processed foods
◦Legumes, potatoes, seafood, dairy products, meat,
fruits
deficiency
◦hypertension
◦most common electrolyte imbalance
◦muscle weakness
toxicity
◦rare from food
◦over consumption of supplements
Adult requirements for potassium are estimated
to be about 2 g/day

85. What Processing Does to
Sodium and Potassium Contents of Foods
Milk (whole)
Unprocessed
Peach pie
Processed
Canned,
cream corn
Instant
pudding
Oat cereal
Fresh peaches
Milks
Chipped beef
Vegetables
Fresh corn
Meats
Roast beef
Fruits
Rolled oats
Grains
Sodium
Potassium
Key:

86. Copper
Functions:
Componentofseveralenzymes,cofactors,and
proteinsinthebody.
Intheproperfunctioningoftheimmune,nervous
andcardiovascularsystems,forbonehealth,
Forironmetabolismandformationofredblood
cells,andintheregulationofmitochondrialand
othergeneexpression.
Functionsasanelectrontransferintermediatein
redoxreactionsandasacofactorinseveralcopper
containingmetalloenzymes.

87. Copper-Deficiency & Toxicity
Deficiency
◦Hospitalized patients & preterm
infants
Signs & Symptoms
◦Defective connective tissue,
anemia, neural problems
Toxicity
◦Rare

88. Copper –Requirements & Dietary Sources
Estimatesofaverageintakesof
copperareabout1.5and1.2mg
copper/dayformenandwomen,
respectively.
Richfoodsourcesofcopper
includeseafood,nuts,seeds,legumes,
wholegraincereals,andchocolate.

89. Manganese
Functions:
Requiredasacatalyticcofactorfor
mitochondrialsuperoxidedismutase,
arginase,andpyruvatecarboxylase.
Cofactorformanyenzymesthat
metabolizecarbohydrates,lipidsand
aminoacids

90. Manganese Deficiency & Toxicity
Deficiency
◦Rare
◦Scaly skin, poor bone formation, growth
faltering
Toxicity
◦Rare
Mine workers
Liver disease

91. Manganese-Requirements & Dietary Sources
High concentrations present in cereals, brown bread,
nuts, ginger, and tea.
AI :
➢infants 0.003 mg (first 6 mnts), 0.6 mg (7–12 mnts),
➢children 1.2 & 1.5 mg (1–3 and 4–8 years, resply),
➢teenage boys 1.9 & 2.2 mg (9–13 &14–18 yrs, resply),
➢adult men 2.3 mg (19 years and older),
➢teenage girls 1.6 mg (9–18 years),
➢adult women 1.8 mg (19 years and older),
➢pregnant women 2.0 mg,
➢lactating women 2.6 mg.

92. Molybdenum
Function:
Cofactorfortheiron-andflavin-
containingenzymesthatcatalyzethe
hydroxylationofvarioussubstrates.
Deficiency
◦Rare
Toxicity
◦No known effects in humans
◦Animals –disrupts reproduction

93. Molybdenum : Dietary Sources &
Requirements
Adult requirements for molybdenum
have been estimated at about 45
μg/day.
Milk, beans, bread, and cereals
(especially the germ) are good sources
of molybdenum, and water also
contributes small amounts to the total
dietary intakes.

94. Chromium
Function:
Essential nutrient involved in carbohydrate and lipid
metabolism
◦maintains glucose homeostasis
Deficiency
Elevated blood glucose
Decreased insulin sensitivity
Weight loss
Toxicity
◦Rare
◦Industrially released chromium
•Richest dietary sources of chromium are spices such as
black pepper, brewer’s yeast, mushrooms, prunes, raisins,
nuts, asparagus, beer, and wine.

95. Chromium
AI values:
-infants 0.2 μg (first 6 months), 5.5 μg (7–12 months),
-children 11 and 15 μg (1–3 and 4–8 years, respectively),
-teenage boys 25 and 35 μg (9–13 and 14–18 years,
respectively),
-adult men 35 and 30 μg (19–50 years and 50 years & older,
resp),
-teenage girls 21 and 24 μg (9–13 and 14–18 years,
respectively),
-adult women 25 and 20 μg (19–50 years and 51 years and
older, respectively),
-pregnant women 29 and 30 μg (less than 18 years and 19–
50 years, respectively), and
-lactating women 44 and 45 μg (less than18 and 19–50 years,
respectively).

96. Fluoride
99% is found in bones and
teeth
Function
◦to promote
mineralization of calcium
and phosphate.
◦Inhibits bacterial growth
in mouth→decreases
cavity formation.

97. Fluoride-Deficiency & Toxicity
Deficiency
◦Results in increased risk of dental caries
Toxicity
◦GI upset, excessive production of saliva, watery
eyes, heart problems, coma
◦Dental fluorosis
◦Skeletal fluorosis

98. Fluoride-Requirements & Dietary Sources
Dietary sources:Tea, marine fish , toothpaste,
added to drinking water.
AI values for fluoride:
-infants 0.01 mg (first 6 months), 0.5 mg (7–12
months),
-children and adolescents 0.7, 1.0, and 2.0 mg (1–3,
4–8, and 9–13 years,respectively),
-male adolescents and adults 3 and 4 mg(14–18 and
19 years and older, respectively),
-female adolescents and adults 3 mg (over 14 years,
including pregnancy and lactation).

99. Ultra Trace Minerals
Nickel
Aluminum
Silicon
Vanadium
Arsenic
Boron