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BiochemistryMacro and micro

nutrientsEditing file

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O B

J E

C T

I V

E S By the end of this lecture, the students

should be able to know:

• Understand the nutritional importance of dietary macro and micronutrients

• Identify major dietary sources and RDAs of macro and micronutrients

• Evaluate the nutritional quality of proteins, the types of dietary carbohydrates, fibers and fats and their benefits

• Discuss the role of macronutrients in causing diseases or conditions such as nitrogen imbalance, diabetes, obesity, atherosclerosis and heart disease

• Understand the functions of micronutrients and the diseases due to their deficiencies

Lecture overview

Macronutrients & Micronutrients

Definitions:Ø 1)Macronutrients:Nutrientsneededbythebody

inlargeamounts(proteins,carbohydrates,fats)• Theyprovideenergyandbuildingblocksfor

proteins,carbohydratesandfatsthatarestored.

Ø 2)Micronutrients:Nutrientsneededbythebodyinsmallamounts(vitamins,minerals,traceelements)(Micro=smallamounts)

ü Requiredformaintainingnormalhealthandpreventingvariousdiseases

ü Theydonot provideenergyü Alotofthemworkascoenzymesandcofactors

supportingthebiochemicalreactions.

EnergyContentofFood:Calories

BodyobtainsenergyasATP

Theenergycontentoffoodismeasuredincalories(Kilocalories)

Onecalorieistheheatrequiredtoraisethetemperatureof1gm.ofwaterby1oC

Proteinsà 4kcal/gmCarbohydratesà 4kcal/gm

Fatà 9kcal/gm

Colorimeteristheinstrumentusedformeasuringcalories.-Proteinsarenoteasilydigestedsoavoidtakingtheminlarge

amounts.-Carbohydratesarethebestsourceofenergy.

-Fatsarethemostconcentratedformofenergy,andtheyhaveharmfuleffectifyoutaketheminlargeamounts.

Whatdoes(9kcal/gm)mean?Itmeansthatifyouburn1gmoffat,9kcalareproduced.

Energy Content Of Food

Deathrateper100,000populationduetoimbalancednutrition(maincause)

Unintentionalinjuriesarecausedbyalcoholaswell.Theseratesshowtheeffectofimbalanceddiet,soitmakes

youatahighriskofheartdiseases,cancer,strokeanddiabetes.

v AcceptableMacronutrientDistributionRange(ADMR)

v Adequateintakeofmacronutrientstopreventtheriskofdisease.

AMDRforadults:CHOs:45-65%

Proteins:10-35%Fats:20-35%

Thesepercentagesarehowtheyshouldbedistributedin

yourdiet.

NutritionalImportanceofProteins:

üProteinssupplyaminoacidsandaminonitrogenforthebodyüNon-essentialaminoacids:bodycansynthesize

Ifyoutaketoomuchproteinstheywon’tbestoredasproteinsandcouldbestoredasfat.

1- Proteins

Essentialaminoacids:Bodycan’tsynthesize,mustbesuppliedinthediet.Thisisthemost importantbenefitofproteins.

Phenylalanine

Valine

Tryptophan

Threonine

Isoleucine

Methionine

Histidine

Arginine

Lysine

Leucine

*Pneumonic:PVTTIMHALL

Nutritional Quality of Proteins:v Whatisit?üAmeasure ofaprotein’sabilitytoprovidetheessentialaminoacidsrequiredfortissuemaintenance.üMeasuredinPDCAASunits.(Digestibility-CorrectedAminoAcidScoring)

üHighvalueindicatesmoredigestibilityandhighquality.(maximumscore1.0>themorethenumberthehigherthequality.)

üProteinsfromanimalsourceswhichisaverygoodprotein :0.82–1.0(milkhasscoreof1)üProteinsfromplantsources:0.4

- Don’tgointodetailsforPDCAASmeasurement.- Alotofproteinsarenoteasilydigested,soagoodqualityproteinwouldbea

proteinthatiseasilydigested andhastheessentialaminoacids.- Youcanhavecombinationsofofplantsourcesinordertomakeitasgoodas

animalsources.Forexample:wheat isrichinmethionineandpoorinlysine,bothareessentialaminoacids,ontheotherside,kidneybeansarerichinlysineandpoorinmethionine,ifyoucombinethesetwoyou’llgetbetterqualityproteins.

SourcesandRDA:

Ø Meat,poultry,fish,milk(havedigestibilityscoreof1.0),wheat,corn,beans,nuts.

v RDA(gms/kgbodyweight)ü Normaladults:0.8ü Athletes:1.0ü Pregnancy/lactation:upto 30gmü Children:2.0Theyneedmorebecausethey’regrowingup.

Don’tmemorizetheRDAnumbersbecausetheydepend

ontheweight.

EXTRA:blackbeansvs.kidneybeans

Metabolicstressmeansincreasedcatabolism.Inpointd:proteinshavelessessentialamino

acidssothey’relessqualified,sotheexcretionwillbehighbecausewedon’tneedtheseproteins.

Nitrogen balance

NitrogenBalance

Normal NitrogenBalance:Inahealthyperson,thenitrogenintakeisequaltonitrogenloss,butthatdoesn’tmeanthatproteins

aretakenandexcretedequally.

Negative nitrogenbalance:Whennitrogenlossismorethanintake

Occursinburns,trauma,illness,metabolicstresswhichcauseanabnormalloss,orifproteinsindiet

arenotsufficient.

Positive nitrogenbalance:• Whennitrogenintakeismorethanloss

• Occursingrowth,pregnancy,lactation,recoveryfromillness.Soyou’restoringproteins.

Nitrogenbalance=howmuchnitrogengoinginsidethebodyasproteinsandhowmuchnitrogenexcreted(mainlyasammonia)

Protein-Energy Malnutritionv Whatisit?

v Aconditionordiseasecausedbynoteatingenoughfoodornot

eatingabalanceddiet.

üMalnutritionduetoinadequateintakeofproteinsorenergy.

ü Twoconditions:

1.Marasmus

2.Kwashiorkor Bothconditionsaffectyoungchildrenandare

causedbyproteinmalnutrition.

Protein-Energy MalnutritionMarasmus Kwashiorkor

Cause

Inadequate intakeofenergy withadequateproteinintake

Theystartbreakingdownproteins(byusingaminoacidsingluconeogenesis)becausethey

don’thaveadequatesourceofenergy.

Inadequate intakeofproteins withadequate energyintake

Age andfood intake

ü 1-3yearü Mother’smilkissupplementedwithfood

(cereals)deficientincalories

ü Afterweaning(atabout1year)(fewmonthsto1year)

ü DietmainlycontainsCHOsTheydon’tgetenoughproteinsfrommilkbecausetheirmothersstoppedfeedingthem(sometimes

becausethey’repoor)sotheyonlygetCHOrichfood.

Symptoms

ü Arrestedgrowthü Extrememusclewastingü Weaknessü Weightlossü Noedemaorchangesinplasmaproteins,

becauseproteinintakeisenough.

ü Edemaü Distendedabdomenü Diarrheaü Dermatitis/thinhairü Enlargedfattyliver(duetoexcessofCHO)ü Lowplasmaalbumin(becausethereisn’tproteins)

2- CarbohydratesüTheir major role: energy productionüRDA:130 grams/dayforadultsandchildrenüTypes in the diet:

ØSimple CHOs: sucrose, fructose, lactose, corn syrupØComplex CHOs: whole grains, pasta, wheat, starch

üCHOintakeaboveRDAcausesweightgainorobesityduetoincreasedfatstorageinadiposetissue.(CHOisturnedintofat)

RDA=Recommendeddietaryallowance.Whenthebodyisn’tgettingenoughcarbs,itturnstoproteins

andbreaksthemdowntogetenergy.

Dietary Fiber

HowtheylowerLDLlevels:Bilesaltsarenotnormallyexcretedoutsidethe

body,theyareproducedforthedigestionoflipidsthengetreabsorbed.

Sodietaryfibersbindtobilesaltswhicharemadeofcholesterol,andexcretethemoutofthebody,

whichleadstomakingnewbilesaltsoutofcarbohydrates.

Wehavetwotypesoffibers:1)Solublefibers:bindtobilesalts,theycandestroy

carcinogens.2)Insolublefibers:helpinmotilityanddiarrhea.

v Whatisit?• The component of food that cannot be broken down by human digestive enzymesØ RDA (gm/day):Men: 38, Women: 25

BenefitsüLowersserumLDLlevels

üReducesconstipation

üPromotesfeelingoffullness

üSlowsgastricemptying(helpfulinlong-termglucosecontrol

inpatientswithdiabetesmellitus)

üReducesexposureofguttocarcinogens

3- Fats

*Whichgiverisetoeicosanoidsthatprovidethromboxaneandprostaglandins>playaroleininflammation(theyhavecardio-protectivefunction)

Fatsindiet• Aconcentratedsourceofenergy(9kcals/gram)

• Supplyessentialfattyacidssuchaslinoleicandlinolenic acids*

• Providephospholipidsformembranefunction

• Sourceoffat-solublevitamins(A,D,E,K)andhelpintheirabsorption

RDA(gm/day) Totalfats:65gmSaturated:20gm

Excessivefatintakecancause:

Atherosclerosis/heartdiseaseObesity

Essential Fatty AcidsTwoessentialfattyacids– unsaturated:

Øa-linolenicacid(w-3fattyacid)*Ølinoleicacid(w-6fattyacid)

*w=omega,w-3=thefirstdoublebondispresentincarbonnumber3.

üDeficiencycauses:scalyskin,dermatitis,reducedgrowth(mostcommonininfants)üUsedforeicosanoidssynthesiswhichappeartohavecardio-protective effects

Ø decreasebloodclottingØ decreasebloodpressure

Essential Fatty Acids

Omega-3FattyAcidsü Sources

Ø PlantsØ Fishoilcontainingdocosahexaenoicacid

(DHA)andeicosapentaenoic acid(EPA)

ü Playanimportantroleas:ØStructuralmembranelipidsØModulatorofw-6fattyacidmetabolism

Effects

Suppresscardiacarrhythmias

¯ Serumtriacylglycerol

¯ Tendencytothrombosis

Lowerbloodpressure

¯ Riskofcardiovascularmortality

LittleeffectonLDLorHDLlevels

Recommendations for Omega-3 Fatty Acid Intake

CHD=Coronaryheartdiseases.

EPA=Ecosapentaenoicacid.

DHA=Docosahexaeonicacid.

By American Heart Association Guidelines

1.Patientswithoutcoronaryheart

disease(CHD)butareatriskofdevelopingit

• Fattyfishtwiceaweek• Includeoilsandfoodsrichina-linolenicacid(flaxseed,canolaandsoybeanoils;flaxseedandwalnuts)

2.PatientswithChronicHeart

Disease• 1gmofEPA+DHAperdayfromfattyfish

• EPA+DHAsupplements

3.Patientswhoneedtolower

triglycerides(fats)andhaveCHD

• 2to4 gramsofEPA+DHAperday

Essential Fatty Acids

Omega-6FattyAcidsü Sources

1. Nuts2. Avocados3. Olives4. Soybeans5. Oils(sesame,cottonseed,cornoil)

ü Effects§ ¯ Plasmacholesterol§ ¯ LDL§ ¯ HDL,consideredasanegativeeffect,

butitcanbecompensated.

TransFattyAcidsv Whatisit?• Unsaturatedfattyacids,behavingmorelike

saturatedfattyacidsinthebody.

ØincreaseserumLDL(butnotHDL)ØriskofCVD

ü Notfoundinplants(animalsonly)ü Formedduringhydrogenation ofliquidvegetableoilsü Foundinbakedfood:cookies,cakes,deep-friedfoods

Theyareharmful,mucheasiertobeoxidizedandcausethrombosis.

1- Vitamins

v Organiccompoundspresentinsmallquantitiesindifferenttypesoffood

üHelpinvariousbiochemicalprocessesincell

üImportantforgrowthandgoodhealth

üEssential

üNoncaloric

üRequiredinverysmallamounts,sotheyaremicronutrients.

ClassifiedBasedonSolubility

Fat-solublevitamins

• A,D,EandK

Water-solublevitamins

• ascorbicacid(vitaminC)

• thiamin(vitaminB1)• riboflavin(vitaminB2)• Niacin(VitaminB3)• pyridoxine(vitaminB6)• biotin• pantothenicacid• folate• cobalamin(vitaminB12)

Mnemonic:KADE(Nameofagirl)

Vitamin E

Antioxidant:preventsoxidationofcellcomponentsbymolecularoxygenand

freeradicals

üMayhavearoleinfertilityandanti-agingeffect

üa-Tocopherolisthemostactiveforminthebody

v SourcesandRDA(mg/day):ØVegetableOil,nuts,seeds,vegetables

ØAdults:15mg,Children:7mg

v Deficiency: (mostlyobservedinprematureinfants)• Defectivelipidabsorption

• AnemiaduetooxidativedamagetoRBCs.• Neurologicalproblems

• Maleinfertility

Functions of Vitamin B1 (Thiamin)

v Activeform:

ü Thiaminpyrophosphate(TPP)

v Coenzymefortransketolase(inHMPpathway)andoxidativedecarboxylationreactions

v Inthiamindeficiency,theactivityofthesetwodehydrogenasesisdecreasedCausing:LowATPproductionanddefectivecellularfunction

• SourcesandRDA(mg/day)

ØPlants,cereals,meat

ØAdults:1.2mg,Children:0.6mg

DisordersofVitaminB1(Thiamin)Deficiency

1. Beriberi:Atypeofchronicperipheralneuritisduetoseverethiamindeficiencycausesweakness,neuropathy,disorderlythinking,paralysis

• Thiaminhasaroleinnerveconduction• Neuropathyaffectsglialcells(astrocytes)ofthe

brainandspinalcordcausingneurondeath

2.Wernicke-Korsakoff syndromeCommoninalcoholics* duetodefectiveintestinalabsorptionofthiaminordietaryinsufficiencyCausesapathy,lossofmemory

*Becausealcoholicsdon’tabsorbvitaminsproperly.

Vitamin C

Functions:Powerfulantioxidant

(preventssomecancers)

Helpsindentine,intercellularmatrix

andcollagenformation*

*Soit’sthegroundsubstance.**That’swhyit’srecommendedwhenapersonisonironsupplementation(speciallyasorangejuice.

***Increasesimmunity.

v SourcesandRDA (mg/day):

• Citrusfruits,tomatoes,melon,peppers

• Men:90mg,Women:75mg,Children:15-25mg

DisordersofVitaminCDeficiencyØ Scurvy

ü Abnormalcollagenproduction

ü Gumsbecomepainful,swollenandspongy

ü Thepulpisseparatedandtheteetharelost

2,3- Minerals and Trace Elements

Macrominerals:(More than100mg/day)

1. Calcium

2. Phosphorous

3. Sodium

4. Potassium

5. Chloride

6. Magnesium

Microminerals:(Lessthan100mg/day)

1. Iron2. Iodine3. Copper4. Manganese5. Zinc6. Cobalt7. Molybdenum8. Selenium9. Fluoride10. Chromium11. Silicon

Iron

Functions:1. Oxygentransportandmetabolism

2. Partofhemoglobin,myoglobin,cytochromes

3. Bodystoresironasferritin,hemosiderinandtransferrin

4. Adultwomenhavemuchlowerironstoragethanmen

• SourcesandRDA (mg/day):

Non-heme iron:Plants(spinach,

beans)5%absorption

Men:8mg,Women:18mg,Children:7-15mg

Hemeiron:Animalproducts(meat,liver),

25%absorption

Hemosiderin:acomplexofferritin.

Transferrin:atransporter.

IronDeficiency:

Ironoverloaddisorderiscausedbymultipletransfusionsofblood.

Take home messages

üMacroandmicronutrientsareessentialforenergyandmaintaininggoodhealth

üVariousdiseasesareassociatedeitherwithmalnutritionorexcessiveintakeofthesenutrients

Q1:Whichofthefollowingisaproteinsource?A- MilkB- FishC- CarrotD- BothA&B

Q2:Omega-3fattyacidismainlyfoundin?A- OceanfishB- InsectsC- HotwaterD- BothA&B

Q3:Vitaminsare?A- CaloricB- RequireddailywithlargeamountsC- EssentialD- BothB&C

QUIZQ4:Wernicke-Korsakoff syndromeisduetodeficiencyinwhichofthefollowingenzymes?A- VitaminB12B- VitaminCC- VitaminAD- VitaminB1

Q5:Ironisconsideredas?A- MicromineralB- MacromineralC- Semi-macromineralD- Nonoftheabove

Q6:Irondeficiencyanemiaiscommonin?A- BreastfeedingwomenB- PregnantwomenC- AdultsD- Newborns

QUIZQ7:Mentiontwoconditionsassociatedwithinadequateproteinintake?

1. Marasmus2. Kwashiorkor

Q8:MentionthreefunctionsofVitaminC?

1. Increasesironabsorption2. Powerfulantioxidant(preventssomecancers)

3. Promoteswoundhealing

Q9:Mentiontwobenefitsofdietaryfibers?

1. LowersserumLDLlevels2. Reducesconstipation

3. Promotesfeelingoffullness4. Slowsgastricemptying(long-termglucosecontrolin

patientswithdiabetesmellitus)5. Reducesexposureofguttocarcinogens

1)D2)A3)A4)D5)A6)B

Suggestions and recommendations

SUMMARY

SUMMARY

T E A MM E M B E R S

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