Download Effect of Palatable Soluble Fibre-Containing

MolecularNutritionandFoodTechnology
EffectofPalatableSolubleFibre-ContainingCarbohydrateFoodson
PostprandialBloodGlucoseResponseinHealthyIndividuals
MasterofScienceThesisby
TajaKarner
May2016
DepartmentofFoodScience
MolecularNutritionandFoodTechnology
EffectofPalatableSolubleFibre-ContainingCarbohydrateFoodsonPostprandialBlood
GlucoseResponseinHealthyIndividuals
MasterofScienceThesis(60ECTS)
TajaKarner(201403218)
Supervisor:
PerBendixJeppesen
AssociateProf.,PhD
DepartmentofClinicalMedicine
AarhusUniversity
May2016
PREFACE
ThisthesisrepresentsthefinalworkofmyMasterdegreeinMolecularnutritionandfood
technology at Aarhus University, Denmark. The experiment work was done in Toronto,
Canada between September 2015 – March 2016 at Risk Factor Modification Center at St.
Michael Hospital, Toronto. The supervisor that guide me through my work and make it
possibleformetoexpandmyknowledgeinCanadaisAssociateProfessor,PhD,PerBendix
Jeppesen.InTorontoIwasguidedbyco-supervisorDr.MDVladimirVuksan.
Acknowledge
IwouldiketothankmysupervisorPerBendixJeppesentohelpmefindtheprojectIwished
to work on and introduce me to the opportunity in Toronto. I also want to thank him for
guidingmethroughtheprocessofwritingamasterthesisreport.SpecialthankgoestoDr.
MD Vladimir Vuksan that trust in me and offer me to do the research in their lab and for
sharingwithmehisknowledge.Thankyouforintroducingmetothefieldofsearchingfor
foodimprovementstohelpdiabeticpatientsmaintaintheirhealth.Furthermore,Iwantto
thankElenaJovanovski,MSc.PhDforguidingmethrougheverystepandhelpingmeclarify
allthequestionsthatpopuptomymind.ThanksalsoRodneyAuYeungforhelpingmewith
patients,statisticsandtakingcareaboutresearchmaterialandfacilitiesthatweusedinthe
experiment.
Iwouldliketothankthecollegesinthelabfortryingallmybakedfoodevenwhentheywere
notbakedsuccessfully.SpecialthankgoestoAny,Rana,Nourah,CarmenandJuliaforthe
excellentworkingatmospheretheycreated.
Manythanksgotomyparents,brothersandwholefamilythatsupportmeonmyjourney
andhelpmefinanciallytomakethiseducationevenpossible.Thankyoutomybestfriend
UrskatocheermeupwhenIwasstressedandtoallmyfriendsandthatstoodbymyside
duringtheproject.
LISTOFPUBLICATIONS
Thisthesisconsistsoftwoparts:
1) Reviewondiabetesandeffectofviscoussolubledietaryfibreonglycaemia.
2) ScientificpaperregardingmystudyperformedinToronto,entitle:
Effect of Palatable Soluble Fibre-Containing Carbohydrate Foods on Postprandial Blood Glucose
ResponseinHealthyIndividuals:ARandomized,Controlled,Double-blindedStudy
ByVladimirVuksan,TajaKarner,AmandaMa,ElenaJovanovski,FeiAuYeung
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LISTOFABBREVIATIONS
ADA:AmericanDiabeticAssociation
AUC:Areaunderthecurve
BMI:Bodymassindex
CHO:Carbohydrates
CVD:Cardiovasculardisease
FFA:Freefattyacids
GI:Glycemicindex
GLUT:Glucosetransporterproteins
GM:Glucomannan
IRS:Insulinreceptorsubstrate
ISF:Insolublefibre
LADA:LatentAutoimmuneDiabetesinAdults
MS:Metabolicsyndrome
NEFA:Non-esterifiedfattyacid,equaltoFFA:Freefattyacid
PGX:PolyGlycompleX
SCFA:Short-chainfattyacid
SF:Solublefibre
T1D:Type1Diabetes
T2D:Type2Diabetes
VFB:Viscousfibreblend
VSF:Viscoussolublefibre
WG:Wholegrain
WHO:WorldHealthOrganization
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TABLEOFCONTENTS
PREFACE.........................................................................................................................................3
LISTOFPUBLICATIONS...................................................................................................................4
LISTOFABBREVIATIONS.................................................................................................................5
TABLEOFCONTENTS......................................................................................................................6
ABSTRACT......................................................................................................................................7
INTRODUCTION..............................................................................................................................8
BACKGROUND..............................................................................................................................10
1. DIABETES..................................................................................................................................10
1.1. Epidemiologyofdiabetes.................................................................................................10
1.2. Type2diabetes................................................................................................................11
1.3. Overviewofglucosemetabolism.....................................................................................12
1.4. PathophysiologyofT2D....................................................................................................13
1.4.1.
1.4.2.
1.4.3.
Abdominalobesity......................................................................................................................................13
Insulinresistance.........................................................................................................................................14
Hyperglycemia.............................................................................................................................................15
2. CARBOHYDRATES.....................................................................................................................17
3. DIETARYFIBRE..........................................................................................................................18
3.1. Definition..........................................................................................................................18
3.2. Dietaryfibreclassifications...............................................................................................18
3.3. Dietaryfibreandfoodprocessing....................................................................................20
3.4. Dietaryfibrerecommendations.......................................................................................20
WHOLEGRAINSHEALTHEFFECTS.................................................................................................22
VISCOUSSOLUBLEFIBRE...............................................................................................................23
1. Viscoussolublefibresupplementation................................................................................23
1.1. KonjacGlucomannan........................................................................................................24
1.1.1. PolysaccharideComplex(PGX)...............................................................................................................26
1.1.1.1. PGXhealthclaims...........................................................................................................................27
1.1.1.2. IncorporatingPGXintodifferentfoodmatrices.............................................................................27
MYMASTERTHESISPROJECT........................................................................................................29
CONCLUSION................................................................................................................................32
PERSPECTIVE................................................................................................................................33
BIBLIOGRAPHY.............................................................................................................................34
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ABSTRACT
Background:Increaseofdietaryfibreintakeandimprovementofpostprandialglucoseresponsecould
be achieved with fibre-enriched carbohydrate products. To evaluate PGX fibre’s incorporation,
sensory assessment for palatability and effect on post-prandial glycemic response of enriched
productswasobservedinhealthyindividuals.
Methods:Thestudyconsistedoftwophases.PhaseI:twenty-onehealthyindividuals(mean±SEM,
age:25.2±9years,bodymassindex[BMI]:22.5±2.4kg/m2)assessedpalatabilitydifferencebetween
control and treatment products using sensory evaluation questionnaires. Phase II: twenty healthy
participants(mean±SEM,age:26.3±10years,BMI:22.4±3.6kg/m2)wererandomizedtoreceive
whitebread,muffins,mashedpotatoesandcreamofwheatafterovernightfastingoneightseparate
occasions. All products consisted of 50 g of available carbohydrates and were either implemented
with4gofPGXorusedascontrol.Bloodglucosesamplesandsatietyratingswerecollectedatfasting
andover2hourspostprandial.
Results:IncorporationofPGXresultsinnodecreaseinpalatabilityfor3outof4foodproducts.There
wasnosignificantreductioniniAUCforanyoftheproductseparately,howeverasignificantreduction
was observed in pooled non-baked products, mashed potatoes and cream of wheat, compared to
control attributes. Peak rises in glucose concentrations were significantly lower for treatment
productscomparedwiththeirrefinedcounterparts.
Conclusions: Addition of VFB to different food matrices must be considered and evaluated on
individualbasisbeforeanyconclusionscanbeformedonitsglycaemiareducingpotential.
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INTRODUCTION
At one hand the general quality of life in past decades is increasing with technology
improvement,butontheotherhandwearefacingaveryconcernincreaseofchronicdiseases
globally. Lifestyle changes that include decrease of physical activity and increased
consumptionofhighlyprocessedfoodhavebeenreflectedinmanymetabolicdysfunctions
knownbythetermmetabolicsyndrome(MS)(WHO2003).MSishighlyconnectedtotherisk
ofdevelopingtype2diabetes(T2D)andcardiovasculardisease(CVD)thataretwodominantly
chronicaldiseasesnowadays(Singhetal.2013).T2Disoneofthediseaseswiththehugest
increase in incidents in the past decades (Ezzati 2016). The prevalence for T2D was firstly
connected to developed countries, however in the last decade much faster growth of
incidentsofT2Disobservedindevelopingcountries(WorldHealthOrganization2016).Even
thoughT2Dusedtoberecognizedasdiseaseofelderpopulation,itisnowpresentalsoamong
children(Dabelea2009).
EventhoughT2Disassociatedwithgeneticpredisposition,environmentfactorsandlifestyle
playsignificantroleandoffereffectiveapproachestopreventfromitsdevelopment(Lam&
LeRoith2012).However,theapproachesareverygeneralandincludetakingcareforoverall
healthwithregularexercise,healthyfood,avoidingsmokingandhavingbloodpressureand
lipidlevelindesirablerange(WorldHealthOrganization2016).Themainrecommendations
of World Health Organization for preventing T2D and its complications include having
sufficient dietary fibre (DF) intake with consumption of whole grains (WG), legumes,
vegetablesandfruitsandlimitedintakeofsaturatedfatandsugartobelow10%ofdaily
caloric intake, separately (Ahmad et al. 2001). However, despite the recommendations
dietaryfibreintakeremainlowerthandesirable(Association2008).
Duetomodernlifestylepeoplefindrecommendationhardtofollow,thereforealotofeffort
isputintoseekingofnewsolutionstohelppeoplemaintainoverallhealth.Additionoffibre
intodifferentfoodproductshasbeenapracticefordecades,howevermostoftheproducts
areenrichedwithinsolublefibrewhichdonotofferdesirableloweringofpostprandialblood
glucose that has been recognized as crucial parameter in diabetes control (Frontoni et al.
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2013). Moreover, most of fibre-enriched products are associated with decrease of
palatability,thereforerefinedproducts,despiteawarenessoflownutritionalvalue,remain
general preference (Association 2008). Understanding of physicochemical properties of
differentfibreandtheireffectsonglucosemetabolismisapromisingwaytoimprovefood
productsavailableonthemarket(Guillon&Champ2000).Previousresultshaveshownthat
the most significant reduction of postprandial glycaemia of carbohydrate foods can be
achieved with viscous soluble fibre implementation (Jenkins et al. 1978). However, high
viscosity does reflect in reduced palatability and therefore ways of implementing viscous
solublefibreincommonlyconsumedfoodwithoutaffectingtheirpalatabilityarestillsought.
Theaimofthismasterthesisistoevaluatepreviousstudiesonhowviscoussolublefibrecan
improve post-prandial glycaemia and help to control blood glucose level and how their
incorporationinfoodproductscaninfluencedietaryfibreintakeandimprovediabetesrates.
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BACKGROUND
1. DIABETES
1.1. Epidemiologyofdiabetes
Diabetesisconsidertobethemostrepresentedendocrinechronicdiseaseintheworld(J.E.
Shaw et al. 2010). In 1980 there were 108 million reported diabetic people in the world,
whereasin2014thisnumberhasincreaseupto422million.Theincreaseratecorrespondto
therisefrom5.7%to8.5%adultpopulationhavingdiabetes(WorldHealthOrganization
2016).Type2diabetesisthemostcommontypeofdiabetesandcontributetoaround90%
ofalldiagnoseddiabetescasesworldwideandto80%ofalldiabeticpatientsinDenmark(J.E.
Shawetal.2010).It’swellestablishedthatthecauseofthedefectisacombinationofgenetic
predisposition and environmental factors. In a contrast to type 1 diabetes (T1D) where a
geneticpredispositionplaysacriticalrole,T2Dismorerelatedtomanyenvironmentalfactors
andthereforeeasiertoprevent(Scheen2003).IncaseofT1D,autoimmuneresponseofa
body reflects in disruption of pancreatic beta-cells and it is being cured with insulin
substitution.Itoccursinchildhoodandprogressthroughyears(Drouinetal.2009).Itwas
assumedthatonlytwoformsofdiabetesexist,howeverthereareotherlesscommonforms.
Oneofthemistype1½diabetesorLADA(LatentAutoimmuneDiabetesinAdults)thatoccurs
inadultagesbuthavethesamemaincharacteristicsasT1D(Fourlanosetal.2005).Itisan
autoimmunediseaseanditneedsaninsulinsupplywhichusuallyhastobeincreasedover
years. The fourth type is called gestational diabetes and can occur during pregnancy of
overweight or obese women (Buchanan & Xiang 2005; Jensen et al. 1999). Abdominal fat
cause decrease of insulin sensitivity which can be harmful for fetus if not controlled with
healthierlifestyleorinsomecaseseveninsulinisneeded(Langeretal.2005).Themainfocus
of this background is going to be T2D since it is the most common and preventable with
dietarychangeslikeincreasingfibreconsumption.
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1.2. Type2diabetes
Type2diabetesisacomplexchronicconditionwheninsufficientinsulinproductionaswellas
insulinsensitivityleadstoincreaseofbloodglucoselevels(Kahn2003).T2Disadiseasethat
doesnotoccurovernightandcannotbelinkedtooneparticulardysfunctioninthebody.At
thepointofdiagnosis,mostoftheabnormalitiesareusuallyalreadypresent,thereforethe
primarycauseishardtoestablish.Itsprogressionisslowandoftenpre-diabeticphase,an
intermediatehyperglycemiastage,canlastcoupleofdecadesbeforethefull-blowndiabetes
occur (Saini 2010; The Expert Committee on the Diagnosis and Classification of Diabetes
Mellitus2003).ThediagnosisofT2Dhavetobedoneontwoseparateoccasionsandinclude
fasting levels of plasma glucose at or above 7 mmol/L or if symptoms as weight loss and
polyuria are present and casual plasma glucose concentration exceeded 11.1 mmol/L is
considerasT2Dmarker(Fonseca2009).
Due to its complexity the pathogenesis of T2D had been a debate for decades. Various
disruptions of endocrine pancreas, liver, skeletal muscle, adipose tissue, central nervous
system and guts may effect glucose metabolism and cause T2D if not treated preliminary
(DEFRONZO 1988). Symptoms that may lead to T2D if not treated have been marked as
metabolic syndrome and include obesity, hypertension, dyslipidemia, cardiovascular
dysfunctionsandcoronaryarterydisease(Scheen2003).SincemostofthepeoplewithT2D
sufferfromobesity,visceralfatadiposetissuesmostpossibleplayacrucialroleindisruption
ofglucosehomeostasisbyelevatinginsulinresistanceinbothhepaticandmusculartissues
(Kahn et al. 2006). Insufficient insulin sensitivity cause hyperglycemia and increase lipid
formation, which leads in overproduction of insulin and potentially to failure of pancreas.
Eventhoughtherearedrugsthattriggerinsulinsensitivity,losingweight,increasingphysical
activityandavoidingglucoseelevationwithhealthydiethavebeenmoreeffectivewayto
controlandavoidpreliminaryconsequencesofT2D(WorldHealthOrganization2016).For
easierunderstandingofthemechanismbehindT2D,glucosemetabolismhastobediscussed.
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1.3. Overviewofglucosemetabolism
Glucoseistheprimarysourceofenergyforallthecellsinourbody,thereforethemechanism
of regulating the amount of glucose available in plasma is very well controlled. The main
hormonesthatcontrolglucoselevelareinsulinandglucagonthataresecretedfrompancreas
(Zierler 1999). Pancreas is crucial organ in glucose metabolism and has an important
endocrineaswellasdigestivefunction.Humanpancreasconsistsofapproximately1million
isletsofLangerhansthatareproducingandsecretinghormonestoregulatethebehaviorof
bodycellsandplayacriticalroleinprovidingenergyforallthecellsinhumanbody.Outof
around3000cellsthatbuildsoneislets,48-59%arebeta-cellsand33-46%alpha-cellthat
havethemajorendocrinefunctioninglucosemetabolism(Cabreraetal.2006).Aftermeal
consumption the blood glucose level increase depending on the amount and type of
carbohydrates consumed and the presence of fat and proteins in the meal (Jenkins et al.
1981).Afterinsulinissecreted,thephosphorylationcascadeoccurs,withIRSphosphorylation
andinitiationofPI3K-AKTpathwaythatcausetheglucoseuptakeinthecell.Furthermore,
intracellular glucose transporter type 4 (GLUT-4) with its translocation to the outer cell
membrane enables the muscle and adipose tissue to uptake the glucose and store it as
glycogen(Saltiel&Kahn2001).Theabsorptionofglucosethroughgutwallisenabledwith
glucosetransporterproteins(GLUT-2)thattransportitintobeta-cells.Thatreflectsinseries
ofreactionsthatincreaseATP/ADPratioandenclosedATP-regulatedK+channelswhichleads
todepolarizationofplasmamembraneandincreaseofcytosolicfreeCa2+(Henquin2004).
Thisstimulatesinsulinsecretionfrombeta-cellsthatisfurthertransportedtoliverandtothe
bloodstreamwhereitisrecognizedbyinsulinreceptorsonthesurfaceofthecells.Receptors
has to be previously activated with insulin receptor substrate-1 (IRS-1), the key signaling
moleculethatinduceglucoseintakewhichreflectinloweringbloodglucoseconcentration
(Choi&Kim2010).Inmuscleandlivercellstheglucoseisusedforshort-termenergystorage
asaformofglycogen,theadiposetissuetaketheglucosefromplasmaandtransformittofat
as a long-term energy reserve, whereas other cells break down the glucose to ATP via
glycolysisandKrebscycleandusetheenergyforproteinsynthesisandothercellsfunctions
(Saltiel&Kahn2001).Insulinsecretionalsoinfluencestheuptakeoffattyacids(FA)andamino
acids(AA)andsuppressproductionofglucagon(Zierler1999).Glucagonisahormonewith
oppositefunctionofinsuliniscalledglucagonandissecretedwhenbloodglucoselevelhas
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fallenandneedstobeincreased.Inthissituation,glucagonstimulatesglycogenbreakdown
toglucose(gluconeogenesis)sothatitisavailableforothercellstouseit(Exton1972).
1.4. PathophysiologyofT2D
1.4.1. Abdominalobesity
ThemainclassificationofobesepeopleincludetheirBodymassindex(BMI)≥30kg/m2that
iscalculatedasbodyweightdividedbysquaredheightinmeters.However,thisclassification
doesnottakeintoconsiderationwheretheextrafatisstored.Ithasbeenestablishedthat
vascular fat accumulated at intra-abdominal cause major complications correlated with
obesity,whereassubcutaneousfatisnotsocritical(Carretal.2004).Toevaluatetheriskfor
T2Ddiabetestheratiobetweenwaistandheightalsoneedstobeconsider(Ashwelletal.
2012). Abdominal obesity reflect in increase secretion of non-esterified fatty acids (also
referredasfreefattyacids-FFA)andvariousotherpro-inflammatorymoleculesasleptin,
tumornecrosisfactor(TNF)-α,resistin,adiponectinetc.thatinfluenceglucosemetabolism
andpotentiallyleadtoinsulinresistanceasshownonFigure1(Montague&O’Rahilly2000;
Kahnetal.2006).Eventhoughabdominalfatwasshowntoleadtoinflammationinthebody,
lipotoxificationandoveractiveintravascularcoagulationfactors,clearcorrelationsbetween
obesityanddevelopingofT2Dhavenotbeenshown(Kahnetal.2006).
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Figure1:FactorsinfluencingdevelopingofT2D,adaptedfromScheen(Scheen2003).
1.4.2. Insulinresistance
Eventhoughclearmechanismofhowobesitycontributetoinsulinresistanceisnottotally
clarified,itiswellestablishedthatitisconnectedtoabnormalsecretionoffreefattyacids
fromhypertrophiedadipocytetissueandthatbotharethemajorfactorindevelopingT2D
(Kahnetal.2006).Asmentionbefore,productionofFFAisincreasedinoverweightpeople
anditreflectsinabnormalitiesininsulin-signalingpathwayasshownonFigure2.Therecent
hypothesisforinsulinresistanceasshownonFigure2includetheactofintracellularFFAon
activationofserine/threoninekinasecascadewhichleadstoIRS-1phosphorylation(Shulman
2004).TheseinactivateIRS-1eventhoughtheinsulinispresentandconsequentlyPI3Kdoes
notactivateglucosetransportationinthecell.Basedonthishypothesis,anyexceededlevel
ofFFAinintracellularspacecaneventuallyleadtoinsulinresistanceofmuscleandlivercells
andinducehyperglycemia(Shulman2004).Moreover,manysignalingandpro-inflammatory
moleculeslikeTNF-αandinterleukin-6(IL-6)weresuggestedtoinfluencethesamepathway
butindifferentsteps(Gaoetal.2002).Toconclude,insulinresistanceiscomplexstatethat
iscausedbyexcessrateofFFAinintracellularspaceandoverproductionofpro-inflammatory
cytokinesbymacrophagesandcontributetodecreaseoffattyacidoxidationthatleadsto
lipotoxicity.
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Figure 2: Mechanism of impaired insulin sensitivity by exceeded intra-cellular FFA
concentrations.AdoptedfromShulman(Shulman2004).
1.4.3.
Hyperglycemia
In normal conditions, increase of glucose in blood stream induces the production and
secretionofinsulinbypancreaticbeta-cellsthatstimulatemuscle,liverandadiposetissues
inglucoseuptake.Incaseofinsulinresistance,thephosphorylationcascadestopsatanyof
the previously mentioned steps and therefore excess glucose remain in the blood stream
(hyperglycemia) (Saltiel & Kahn 2001). Many studies have demonstrated that defects in
muscleglycogensynthesisplaycrucialroleinloweringinsulinsensitivity,sincethisshowsup
to be the major pathway for glucose metabolism in the condition of hyperglycemia and
hyperinsulinemia(Shulman2004).AsshownonFigure3,impairedmuscleinsulinsensitivity
reflectsininactiveGLUT-4transporterandconsequentlyreductionofmusclescellsabilityof
glucoseuptake(Samueletal.2010).Oftenhepaticgluconeogenesisisalsonotsuppressed
whichleadtoadditionalelevationofglucoseconcentration.InthedevelopingstagesofT2D,
insulinsensitivityisreducedandforsomeperiodthebodyisstillabletomaintainnormal
glucoselevel,howeverovertimeinsulinsensitivitydrasticallydecreaseifnottreatedandlead
to hyperglycemia. Since the insulin is not efficient, the beta-cells keeps producing high
amount of insulin which over time leads to beta-cells dysfunction. Both lipotoxicity and
hyperglycemiaarecorrelatedwithdecreaseofbeta-cellmassandfurthercomplicationsof
diabetes(Reaven1988).
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Figure3:Comparisonofmuscleglucosemechanisminnormalcells(left)andinthecaseof
insulinresistance(right).AdoptedfromSamueletal(Samueletal.2010).
ImportantmechanismfordevelopingT2Disrelatedalsotodyslipidemia,whichisdefinedas
eitheroverlyincreasedleveloftriglycerides(TG)ordecreasedlevelofHDL-cholesterolbutit
isnotgoingtobediscussedinthismasterthesis(Scheen2003).
AllmentionedmechanismdefectsoccurinvariableproportionsinpatientswithT2Dandtheir
degreeofcomplicationcanimproveovertimeiflifestylechangesaretakingintoaccount,
otherwisethedysfunctionofmechanismincreasewithdiseaseprogression(Scheen2003).
Oneofthelifestylechangesthatisrecommendedbymajorhealthagenciesandgovernment
bodiesistheincreaseofdietaryfibreconsumption(Ahmadetal.2001).ItscorrelationtoT2D
prevention and future opportunities for increasing their consumption are discussed in the
nextchapters.
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2. CARBOHYDRATES
Carbohydrates(CHO)arethemostconsumedmacronutrientsgloballyandcontributeto40–
80 % of daily caloric intake, where lower range are referred to developed and higher to
developingcountries(Burtonetal.2011).SinceT2Disdirectlyconnectiontocarbohydrate
metabolism,itwasadebatefordecadeswhetherdifferenttypeofcarbohydratesplayarole
in preventing or causing defects in glucose metabolism. Studies had shown that type of
dietary carbohydrates and their quantity are both critical in causing obesity and other
contributed chronic disease as T2D and cardiovascular dysfunction (Mann et al. 2007).
Increase of T2D over the years was correlated with increase consumption of refined
carbohydratesdepletedinfibrethatbroughtoutthehypothesisthatdietaryfibremaybean
important parameter in blood glucose control (Mokdad et al. 2003). Those suggestions
accelerated researchers to investigate carbohydrates metabolism and it was in 1981 that
Jenkinsetalintroducedtheuseofglycemicindex(GI)toclassifydifferentcarbohydratefoods
(Jenkinsetal.1981).GIrepresentsthepercentageofglucosethatappearinbloodstreamafter
mealconsumptioncomparedtothereferencemealwhichisusuallyglucosesolutionorwhite
bread.It’scalculatedasaratiobetweenareaunderthecurve(AUC)ofagivenmealdivided
byAUCofareferencewithsameamountofavailableCHO(Jenkinsetal.1981).Themost
significantfactorthatinfluenceglucoseavailabilityisthecontentofdietaryfibrewhichtend
toimpedethehydrolysisofcarbohydratesinsmallintestinalandmaydecreasethediffusion
rateofhydrolyticglucosethroughoutthegutlumen(D.J.A.Jenkinsetal.1987).Itseffect
dependsonthetypeandquantityoffibre,howevertheoveralleffectoffibreonGIcannot
be assumed only by fibre characteristic since it depends on many circumstances that are
addressedinthenextsections(Jenkinsetal.1981).
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3. DIETARYFIBRE
3.1. Definition
Eventhoughthetermdietaryfibreisinusedformorethan50years,itsdefinitionhasbeena
discussionfordecades.MostrecentCODEXdefinitionclassifiesdietaryfibreas:
“Dietary fibre means carbohydrate polymers with ten or more monomeric units, which are
not hydrolysed by the endogenous enzymes in the small intestine of humans and belong to
the following categories’:
—ediblecarbohydratepolymersnaturallyoccurringinthefoodasconsumed,
—carbohydratepolymers,whichhavebeenobtainedfromfoodrawmaterialbyphysical,
enzymaticorchemicalmeansandwhichhavebeenshowntohaveaphysiologicaleffectof
benefittohealthasdemonstratedbygenerallyacceptedscientificevidencetocompetent
authorities,
—syntheticcarbohydratepolymerswhichhavebeenshowntohaveaphysiologicaleffectof
benefittohealthasdemonstratedbygenerallyacceptedscientificevidencetocompetent
authorities
Footnote1:Whenderivedfromaplantorigin,dietaryfibremayincludefractionsofligninand/orother
compoundsassociatedwithpolysaccharidesintheplantcellwalls.Thesecompoundsalsomaybemeasuredby
certainanalyticalmethod(s)fordietaryfibre.”
Footnote2:“Decisiononwhethertoincludecarbohydratesof3to9monomericunitsshouldbeleftupto
nationalauthorities.”(Jones2014)
In this definition are therefore included cell wall polysaccharides, lignin, resistant starch
molecules and other minor components that have been shown to have beneficial
physiologicaleffects(Mongeau&Brooks2016).Thecompositionandtheirbenefitsonhuman
healthdifferfromitsoriginandphysiologicalproperties(Otles&Ozgoz2014).
3.2. Dietaryfibreclassifications
Tounderstandandpredicthowspecificfibreinfluenceconsumers’healthmanythingshave
tobeconsider.Duetohugevarietyoffibreaspartofhumandiet,itisnotpossibletolink
18
them to specific physiological effect without specifying and classifying them into different
groups(Lattimer&Haub2010).MoststandardclassificationofDFisbasedontheirsolubility,
even though it’s mainly focused on fibre’ chemical properties and does not help with
understanding of physiological responses (Flamm et al. 2001). Firstly, it’s should be
acknowledgedthatthedegreeofsolubilityinwatermaybedifferentthaningastrointestinal
tractduetodifferentphysicalconditions(Guillon&Champ2000).Moreover,someoftheDF
might be soluble in saliva but not in acidic conditions present in stomach (e.g. pectins)
(Wanders et al. 2014). It was long believed that soluble fibre (SF) were not common in
consumedfoodsbuttheydocontributetoonethirdoftotaldailyfibreintake(Mongeau&
Brooks2016).SFaredissolvedinwaterandareabletoformgelswhichmakesthemslowly
passingthroughsmallintestineandhighly-fermentedinlargeintestine.Ontheotherhand,
insoluble fibre (ISF) cannot be dissolved in human gastrointestinal track and they act like
bulking agent, but can only be fermented by bacteria to limited extend (Wong & Jenkins
2007).
MoreimportantparametersthatbringusclosertounderstandingofDF’shealtheffectare
physicochemical properties of fibre like viscosity and fermentability. Viscous soluble fibre
(VSF) are able to thicken and have gelling properties when mixed with fluids, which as
suggestedcanslowdowngastricemptingandabsorptionofnutrientsinsmallintestine.The
mostresearchedVSFaregums,pectins,beta-glucansandKonjacGluccomannan.Degreeof
gelling capacity depend on their chemical composition as well as food preparation
(Schneeman1998;Dikeman&Fahey2006).
Theextentoffermentabilitydependsonfibreproperties,butit’sassumedthat70-80%of
totalDFintakearefermented,includingISFthathaslongbeenassumedtonotbefermented
atall(Mongeau&Brooks2016).Fibrethatareeasilyfermentedareincreasingproductionof
shortchainfattyacids(SCFAs)thathavebeenlinkedtomanyhealthbenefits.Whereas,fibre
thatarefermentedslowlyorcannotbefermentedcompletelyactlikebulkingagentthatare
beneficialforlaxationandincreasingstoolweight(Schneeman1998).
19
3.3. Dietaryfibreandfoodprocessing
Afterunderstandingclassificationoffibrethatarebasedontheirchemicalcompositionand
structural characteristic, one also have to take into consider food processing practices
(Guillon&Champ2000).Assoonastheoriginfoodischanged,thepropertiesofDFcontent
might be influenced. Heat treatment is a process that can break down glycoside bonds in
polysaccharideswhichmightreducetheDFcontentorchangetheratiobetweenISFandSF.
Withheatinginthepresenceofaminoacids,Millardreactionofpolysaccharidesisstarted
whichproducenewpolymersthatlosethefibreproperties(Mongeau&Brooks2016).One
ofthefirstthingsthatwasobservedwhentestinghowfoodprocessinginfluenceglycemic
responsewasthatcookedfoodlikewheat,cornandpotatoesingestedsignificantlyhigher
glucoseresponsethantheirrawcontributes(Bornetetal.1989).Fibreareinfluencedalsoby
cutting,milling,cookingandboiling.Thegreateristhetransformationofgrains,vegetables
andfruitsfromtheiroriginstructure,thelowerisintegrityofacellwall,lesslikelyitistohave
beneficialeffectsonhealth(Guillon&Champ2000).However,changesthatcanbeobserved
while food processing does not necessary correspond to what will be the change while
digested.Whenfoodprocessincreasesolubilityandviscosityofameal,itdoesnotnecessary
correspondtoincreaseviscosityinsmallintestinal.Sincethereisnoinvitromethodsthat
would be able to show relationship between physicochemical properties of DF and their
physiological effect, clinical studies have to be conducted to evaluate food processing
influenceonhealthbenefitsoffibre(Guillon&Champ2000).
3.4. Dietaryfibrerecommendations
Dietaryfibrearepresentineveryunprocessedfoodlikegrains,vegetables,fruits,nutsand
seeds.Eventhoughtheycanbefoundinsuchbroadareaoffoodproducts,mostofthepeople
failtoreachdailyrecommendations.Averagepersonfibreconsumptionhasbeendecreased
duringlastdecadessincetheamountofprocessedDF-freefoodhasdramaticallyincreased
(Mannetal.2015).
USArecommendationsofdietaryfibretoreachadequateintakeare14g/1000kcalwhich
correspondtoapproximately28g/dayforwomenand36g/dayformen(Usda&Dhhs2010).
In1994USAreportedthat76%ofpeoplewhoeatbelow20goffibreperdayhaveself20
reportedthattheyareeatingsufficientamountoffibredaily(Alaimoetal.1994).Eventhough
theawarenessofimportanceofdietaryfibrehasincreased,thefoodconsumedisreducedin
fibrecontentanditreflectsintheaverageintakeoffibreonly15g/dayinUSA(Association
2008).It’ssurprisingthatmostofthefibreconsumedbyAmericanscomesfromwhiteflour
and potatoes despite low DF values, since their consumption are the highest (Association
2008).InDenmarkandotherScandinaviancountriestherecommendationofDFintakeare
25-35g/daywhichcorrespondtoUSguidelines(NordicNutritionRecommendation2012).In
2008therewereonly6%ofDanesthatmeettheDFrecommendationseveryday,therefore
the country started the campaign to raise the awareness of health benefits from eating
enoughWGproductsandfibre.In5yearsafterthecampaignstarted,27%ofadultDanes
and 43 % of children met the recommended amounts of whole grain food per day. The
average consumption of whole grains have risen from 36 g/day to 63 g/day (75g/day
recommended),respectively(DanishWholeGrainPartnership2014).
21
WHOLEGRAINSHEALTHEFFECTS
MainrecommendationsareusuallyapproachingincreaseofWGconsumptioneventhough
therearecontroversialresultsbetweenepidemiologicandclinicalstudieswhetherWGhave
aneffectondiabetesparameters(Schulzeetal.2007;Jenkinsetal.1978).Ononehandmany
epidemiologicstudiesshowthatWGandcerealsthatmainlyconsistofinsolublefibrehave
the most prospect effect on risk of cardiovascular disease, incident of T2D and mortality
(Schulzeetal.2007).Beneficialeffectsobservedincohortstudiesaremostpossiblearesult
of many beneficial ingredients in WG and cannot be directly correlated only to higher DF
intake(Babioetal.2010).InadditiontoISF,wholegrainsalsocontainpolyphenols,vitaminE
andmagnesiumthatpossiblyinfluenceoverallhealthbeing(Counciln.d.).Cohortstudiesare
duetomanycorrelationsthatmightinfluencetheresults,notabletoprovidereliablefactsto
establishdefinitiveconclusions(Concatoetal.2000).However,theirresultsarestimulating
researchgroupstoconstructrandomizecontroltrialstotestpredictedcorrelations.
CohortstudiesincludedinreviewbyBabioetal,havesimultaneouslyshowndecreaseinrisk
fordevelopingT2DassociatedwithhigherWGintake(Babioetal.2010).However,therewas
no specification of grain and fibre types that could give us clear information of what has
caused those results. One of the shown correlations from cohort studies was that
cardiovascularincidentsaremoreconnectedtoelevatedpostprandialglycaemiathanfasting
glucose,thereforemoreclinicalstudieswereconductedtotesttheeffectofcarbohydrate
productsonglucoseresponseandevaluatetheirGI(Jenkinsetal.1987;TheDECODEstudy
1999;Brand-Milleretal.2003).ClinicalstudieswerenotabletoshowbeneficialeffectofWG
onglycemicresponse,thereforeAmericanDiabetesAssociation(ADA)in1995concludedthat
dietaryfibreprobablyhaveinsignificanteffectonglycemiccontrol(Complications2002).The
inconsistencyofresultsisareflectionofdifferentdietaryfibrepropertiesthatwasfirstlynot
taken into account. Studies of dietary fibre were in the beginning mainly focused on the
question how much fibre is needed to have beneficial effect and secondly they have
investigatewhattypeoffibreofferbetterphysiologicaleffects(Guillon&Champ2000).In
clinicalstudies,ISFthatarethemaintypeoffibreinWGproducts,didnotperformdesirable
effectonglycemicrespondandotherriskfactorsofdevelopingT2D(D.J.Jenkinsetal.2002).
22
VISCOUSSOLUBLEFIBRE
In 1978 Jenkins et al. first compared different DF and their analogs to test the effect on
glucosetoleranceandtoinvestigatecorrelationsbetweenfibrepropertiesandtheireffect
(Jenkinsetal.1978).Outofsixdifferentfibreaddedtotheproducts,onlyguargumshowed
significantreductioninpeakriseofglucoseconcentration.Theyshowedpositivecorrelation
between increase viscosity of fibre added and greater reduction in peak rise and AUC.
Increasedviscosityreflectsinslowerglucoseabsorptionandtransittimeandthereforeoffers
effective way to decrease postprandial glycaemia. That was even further confirmed when
they compare the effect of the same fibre with no viscous properties and showed that
hydrolyzed guar gum did not perform any reduction of glucose response. The suggested
mechanism is twofold, firstly viscous fibre delay gastric emptying and transit time and
secondlyslowdownglucoseabsorptioninintestinal(Jenkinsetal.1978).
Evenwhencomestoviscousfibre,notallofthemperformthesamephysiologicaleffect.In
vitrostudiesshowedthatglycemicresponseofsolidfoodswithincorporatedVSFcorresponds
tomolecularweightoffibreandtheirconcentrationthatinfluencedviscosity(Lan-Pidhainy
etal.2007;Toshetal.2008).However,thesituationindigestivesystemmightbedifferent
due to different physiological properties and environmental factors, therefore each fibre
effectshavetobetestedindividually(Guillon&Champ2000).
1. Viscoussolublefibresupplementation
EatingsufficientamountofSFisachallenge,sincetheyareonlypresentinbeans,lentils,chick
peas, okra, barley, and oats. Moreover, it was shown that some of the natural occurring
soluble fibre, like agar and pectin, do not have an effect on postprandial glycaemia even
thoughtheymightdelayfooddigestion(Sanakaetal.2007).Forguargumitwasshownthat
itmayloseitsactivityduetohydrolysisinstomachacidthatreflectsinreductionofviscosity
(Regand et al. 2009). Moreover, even oats that are rich in viscous beta-glucans, show no
differencesinGIcomparedtootherhighGIproducts(Granfeldtetal.1995).Therefore,many
supplementsareavailableonthemarketthatcouldhelpinglycemiccontrol(Chutkanetal.
2012).Oneofthesupplementsthatjustrecentlyhavegottheapprovedhealthclaimfrom
23
Health Canada is a Polysaccharide Complex (PGX – PolyGlycompleX), containing
glucomannan,xanthangumandsodiumalginate,thatwasusedinthestudyconductedfor
thismasterthesis(USPatentNo:8,062,686)(Anonn.d.).
1.1. KonjacGlucomannan
The main component of PGX is a glucomannan that is derivated from Konjac root
(AmorphophallusKonjac)anditisasoluble,fermentableandhighlyvisousdietaryfibrethat
haveabilitytoabsorbupto50timesitsweightwhendiluted(Keithley&Swanson2005;Davé
&McCarthy1997).
Picture1:AmorphophallusKonjacillustrationoffibreisolationsteps.Sourcewebpagewrapfataway.com–linkatPicture
reference(1).
24
Picture2:AmorphophallusKonjacrootusedforglucomannanextraction;sourceWikipedia–sourcewebpagenaturdrogeriet.dk–linkatPicturereference(2).
Konjacglucomannan(GM)has5timeshigherviscositythanguargumandbeta-glucansand
itwasshowntobeoneofthefibrewiththehighestviscosity(Davé&McCarthy1997).In
Japanisecultureithasbeenusedasfoodandremedyforaverylongtimeandtheywerealso
thefirstonethatstartedtoinvestigatetheirpositiveoutcomesasadietaryfibre(M.etal.
1980).
Konjacglucomannanwasshowntobebeneficialformanyhealthparameters.Vuksanetal.
were the first to show its beneficial effect on high-risk diabetic patients when using it
implementedintobiscuits.High-riskindividualswithT2Dgainedimprovementinmetabolic
controlwhenGM-enrichedbiscuitswereaddedtoconventionaltreatment(drugtherapyand
low-saturated fat diet)(Vuksan et al. 1999). Glucomannan has shown beneficial effect on
glycemic control when used as a longer as well as shorter (acute) treatment. Its use also
reflects in decrease of short-term marker of degree of diabetic control – fructosamine,
howevertheyshownoeffectonfastingorinsulinsecretion.ItwassuggestedthatGMmay
25
potentiate the effect of drugs used for diabetes treatment. Furthermore, the same group
continueswiththestudyandtestGM-enrichedbiscuitswithwheatbranfibrebiscuitstosee
thedifferenceineffectofVSFcomparedtoinsoluble.Resultswereverysimilartoprevious
research and supported better glycemic control for GM-group, significant reduction was
observed in hyperglycemia and hyperlipidemia (Vuksan et al. 2000). Great reduction
propertiesforloweringLDLcholesterolhavebeenshownandifcomparedtootherfibre,GM
offerstriplelipid-reductioncomparedtopsyillum,oatproductandguargumaswellastwice
thecapacityofpectins(Brownetal.1999;Vuksanetal.2000).
1.1.1. PolysaccharideComplex(PGX)
PGXisaformulationofthreeviscousfibrethatactsynergisticallyandinduceseveraltimes
higherviscositywhenusedtogether.Thisofferagreatpotentialtoachievethesamehealth
resultsusingsmallerquantities.Sinceimplementingviscousfibreinfoodremainsachallenge
duetotheirhighviscosity,implementingPGXmightbethesolutiontoobtainpalatabilityof
products.ComparedtootherVSFlikeguargumthatreachesextremeviscosityimmediately
whenmixedwithwater,PGXgelsslowerandreachesthehighestviscositywithdelaywhich
isverybeneficialinfoodproduction(Brand-Milleretal.2010).A.L.Jenkinsetalshowedthat
adding10gofVFBtobiscuitsresultsin74%ofGIreductioninhealthyparticipantsandin63
%GIreductionindiabeticpatientscomparedtowhitebreadcontrol,respectively(Jenkinset
al.2008).Tocomparethiswithotherfibre,GlycemicReductionIndexPotencial(GRIP)that
tells the degree of reduction per gram of added fibre, was calculated. GRIP values are
therefore7.4whenusedinhealthypatientsand6.3fordiabeticpatients,whichisstronger
reductionthanwasreportedofanyofothersolublefibre,evenGMalone(A.L.Jenkinsetal.
2002;Chearskuletal.2007;Sanakaetal.2007;Dahletal.2005).
PGX is very potential fibre blend also because of its effect on weight loss (Onakpoya &
Heneghan 2015). As mention before, T2D is very correlated to vascular fat and the first
recommendationeverydiabeticpatientreceiveistoloseweight.Fibre-enrichedmealshave
lowerenergydensesincethevolumeofthevolumeofthemealincreaseandreflectinhigher
satiety.Moreover,theyaredigestedslowerandareabletoprolongthefeelingoffullness
alsoduetotheeffectonhormonalhungersignalization(Kristensen&Jensen2011).Theeffect
ismostpossiblethreefold,firstlyviscosityofamealincreasetransittimeandreflectsinslower
26
gastricempting(Dikeman&Fahey2006).Secondly,themetaboliceffectisobservedinslower
absorptionofglucoseandothermacronutrientsthatreflectsinlowerpostprandialglucose
elevation,andthirdly,endocrineeffectwasobservedinlowerproductionofhunger-related
hormones like peptide YY, glucagon-like peptide-1 (GLP-1) and cholecystokinin (Wren &
Bloom2007;Jenkinsetal.1978).Thesecharacteristicsarealltheeffectiveapproachestohelp
inweightcontrol(Howarthetal.2009).StudyconductedbyVuksanetalcomparedviscous
fibre blend preload (same properties as PGX) effects on food intake and conclude that
significantlylowerintakewasobservedinVFBgroupcomparedtoinsolublecellulosefibre,as
wellasGMitself(Vuksanetal.2009).
1.1.1.1.
PGXhealthclaims
In May 2016, Health Canada approved health claims for the use of PGX in food industry
referringtoreducingofpostprandialglycaemiaandcholesterol.Inpostprandialglycaemia,
they conclusion was based on six randomized control trial with cross-over design, that
showedsignificantreductioninpostprandialglucoseiAUCin80%oftreatmentarms.The
effectisachievedwhenaminimumof5gofPGXisaddedtoconsumemealdirectlyprior
consumption.ThishealthclaimisnotallowedifPGXisaddedtoproductsthatrequireany
kindoffoodprocessingpriorconsumption,sincethereisnoevidencetosupporttheeffect
whenenrichedmealsarebaked,frozenorboiled(Anonn.d.).Incholesterolloweringeffect,
fourstudiesshowedsignificantreductionintotalcholesterolfor75%oftreatmentarmsand
inLDLcholesterollevelsforallarms.Theseresultsrequireaminimumof10gofPGXdailyfor
atleast2weekswhenfibreareaddeddirectlypriorconsumption(Anonn.d.).
1.1.1.2.
IncorporatingPGXintodifferentfoodmatrices
AllthebeneficenteffectsofPGXwereshownwhendrypowderwassprinkledonthetopof
foodmealsrightbeforeconsumption.However,askingpeopletosprinklesomethingonthe
topofthefoodisnotthemostefficientwaytomakegeneralpopulationeatmoresoluble
fibre.Therefore,RiskFactorModificationCenterinSt.MichaelHospitalinToronto,whereI
didthepracticalworkforthismasterthesis,havegotthevisionofimplementingPGXinto
commonlyconsumedrefinedcarbohydrateproductsduringprocessing.Refinedproductsare
despiteawarenessoftheirlownutritionalvalue,stillthemostconsumedcarbohydratesin
27
Canada and USA (Association 2008). Whole grains are recommended by general health
institutions,butduetolowerpalatability,noimprovementinamountoftheirconsumption
havebeenachievedinlastdecades(Association2008).Apotentialwaytoimprovethiscould
be to implement PGX into different refined carbohydrate products with retaining their
palatability.SincePGXishighlyeffectiveinloweringpostprandialglycemia,loweramountcan
beaddedtofinalproducts,whichmightbeapotentialwaytonotinfluencepalatability.
28
MYMASTERTHESISPROJECT
MyworkinTorontostartedwithbakingandpreparingtestingsamplestoensureIwasable
topreparethesameproductsthathavebeendonebefore.Beforemyarrivaltheyalready
conductedthephaseIofthestudy,sotheyalreadyknewthattheimplementationofPGXin
productdidnotinfluencepalatabilityinmostofthecases.
Picture3:Theexampleofbakedproductusedinthestudypriordividingintosample;picturetakenbyTajaKarner.
Afteralltheproductswerebaked,preparedandsampledwerecruithealthyindividualsto
participateinthestudy.RecruitmentroomisshownonPicture2.
29
Picture4:RecruitmentroominRiskFactorModificationCenter(RFMC)inSt.MichaelHospital,Toronto,Canada;picture
takenbyTajaKarner.
.
Picture5:LaboratoryinRFMCwherebloodsampleswereanalyzed;picturetakenbyTajaKarner..
Onthepicture3isthelabweusedforanalysisbloodsamples.Afterwefinishwithparticipants
and sample analysis, I focused on analysis of results and compared them to what has
previouslybeenestablished.Ilearnedalotabouttheprotocoloftheclinicaltrails,which
30
thingshavetobetakeninaccount,whatcangowrongandhowtopreventit.Mostofallit
wasanexcellentexperiencethatwillhelpmetounderstandotherclinicaltrialsmoresinceI
wasonceapartofone.
The results of our study showed beneficial effects in lowering postprandial peak values in
glucoserise,howevernoeffectwasobservedinglucoseiAUC.Interestingobservationfrom
theindividualmealresponsesisthatbothcreamofwheatandmashedpotato(non-baked)
treatments displayed a slightly more prominent glucose lowering response compared to
whitebreadandmuffintreatments(bakedproducts).Itisverylikelythatun-sufficientability
toreachfibre’shighestviscositymaskeditspositiveeffectonpostprandialglycaemia.Even
thoughthereweresignificantresultsinmanyaspectsinoveralltreatmentproductscompared
tooverallcontrol,productsindividuallylacksignificanceanddidnotperformasdesirable.For
detailedresultsrefertothepaper:“VladimirVuksan,TajaKarner,AmandaMa,ElenaJovanovski,
FeiAuYeung:EffectofPalatableSolubleFibre-ContainingCarbohydrateFoodsonPostprandialBlood
Glucose Response in Healthy Individuals: A Randomized, Controlled, Double-blinded Study” (not
publishedyet).
31
CONCLUSION
Consumption of highly viscous fibre was shown to successfully lower postprandial blood
glucoseandofferpotentialwaytoaddresshighglycemicresponsesrelatedtoincreaseriskof
developingT2D.IncorporationofVSFintocommonlyconsumedCHOproductshasapotential
to reduce GI of highly processed food. Since VSF incorporation reflect in lower products’
palatability, fibre blends like PGX with fibre combination that acts synergistically and can
perform the same health effects when used in smaller dosage, might offer a solution to
developpalatablefibre-enrichedproducts.
Intheperformedstudywewereabletoobtainpalatabilityof3outof4products.However,
nosignificanteffectwasshowninglucoseiAUCbetweenfibre-enrichedandcontrolsamples.
SincehealthyclaimregardedPGXrefertotheuseoffibreblendsprinkledonthefoodright
before consumption, cooking and baking process in our study might influenced overall
potential. Moreover, it was concluded that 5 g of PGX are necessary to perform desirable
physiologicaleffect.However,inthestudyperformed,only4gwasimplementedintofood
products.Eventhoughthesuccessofimplementingisnotprovenefficientlyyet,weshould
nottakethisopportunityforgrantedandmorefacilitiesandcompaniesshouldworktogether
andfindthebestsolutionhowtoincorporatethisorsimilarhighlyviscousblendsintovariety
of products. Eating higher amount of fibre and still enjoying hedonic appearance of refined
productcouldbeapotentialwaytoimproveoverallhealth,decreasediabetesratesandimprove
people’sdiets.However,theproposeofthisimprovementisnottosupportpeopletoeatmore
refinedproducts,thereforeclearstatementshouldbemadetoclarifythatthisisstillnotahealthy
mealduetolownutritionalvalue. Clear and non-misleading marketing should be a priority
whenputonamarket.
32
PERSPECTIVE
FurtherdevelopmentofproductswherePGXcouldreachitsmaximumviscosityproperties
shouldbeconsidered.PGXcouldbeaddedtovariousdifferentproducts,basedonthemost
consumedrefinedproductinspecificcountry.AddingPGXtocerealsandwhitebread,which
aremosttraditionalbreakfastfoods,isapotentialwaytohelpconsumersnottoriseglucose
leveltoohighfirstthinginthemorning.ThatmightlowertheriskofdevelopingT2D,since
insulinsensitivityisatitslowestpointafterovernightfasting,possiblyduetoelevationofFFA
duringthenight(D.J.Jenkinsetal.1987).Itwouldalsobeinterestingtolookintosecond
mealeffect,sinceitwasshownthatmetabolicresponseofamealmayinfluencenextmeals
inaday.Ifweprovidebreakfastproductswithincreaselevelofviscoussolublefibre,itmay
flattertheresponseofthenextmeal,evenifrefinedanddonotcontainanyfiber(Jenkinset
al.1982;Brand-Milleretal.2010)
Long-termstudytoevaluatetheeffectofeverydayconsumptionofdevelopedproductsin
diabetic patients could be considered and evaluation of its effect on hyperglycemia and
hyperlipidemiacanbeaninterestedaspecttoseehowitcanbenefitpatientswithdiabetes.
33
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