Re: Guar gum and glycemia

[Guest guest]

This seems to say that guar gum alters food structure & lessens it's

access to digestive enzymatic activity. They mention only amylase, but

could there be others? This must be why some users report weight loss. I

wonder if this is something to be cautious about. I hope not because I

love the improved glycemic control that I feel from using guar gum.

Al Pater wrote:

>Guar gum and glycemia

>Hi All,

>

>The below excerpts from the available pdf for the Medline citation appear to

indicate that guar gum is superior to insoluble and other soluble fiber and

highly effective for reducing the glycemic response to different

carbohydrates-containing foods. It seemed that the effectiveness was much

greater on a percent basis for the pasta versus the bread for guar gum reducing

the glycemic response.

>

>Brennan CS.

>Dietary fibre, glycaemic response, and diabetes.

>Mol Nutr Food Res. 2005 Jun;49(6):560-70.

>PMID: 15926145

>

>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstr\

act & list_uids=15926145 & query_hl=77

>

>... 9 The physiological role of dietary fibre:

>effect on the carbohydrate metabolism

>DF has been shown to affect the rate and extent of starch

>degradation.In particular,soluble DF has been shown to

>reduce the rate of starch digestion and alter the rate of glu-

>cose absorption [8,47 ].Research has concentrated on the

>use of guar gum in food systems as a postprandial glucose

>modifying ingredient [27 ].Similarly cellular components

>of cereal grains,such as oat b -glucan gum,have been shown

>to have nutritional benefits [48 –50 ].

>The viscosity-altering behaviour of these soluble DFs

>within the small intestine must account for some of these

>effects,however,the DFs also appear to alter the structure

>of the foods and hence the accessibility of the starch gran-

>ules to the amylase enzymes [27,51 ].For instance,a range

>of DFs (insoluble and soluble)have been used in the pro-

>duction of pasta and bread.In vitro starch degradation of

>these products has shown that the addition of DF has an

>effect in reducing the amount of glucose produced follow-

>ing digestion with amylase [51 –53 ].This reduction in glu-

>cose can not be explained just on the basis of the DF exert-

>ing a dilution factor on the starch component of the food.

>Determination of residual starch following digestion indi-

>cates that soluble fiber (such as inulin)additions to pasta

>(Fig.2)significantly reduces the amount of starch digested

>over a 300 min period.In many cases the magnitude of this

>response is a direct function of dose.

>

>Table 2. Predicted GI values of cereal foods following addition of soluble and

>insoluble DFs

>--------------------------

>-------------Dietary fibre added

>Type-----Amount Bread PGI Pasta PGI

>-----------------------------

>Control 0.0 94.4±1.6 45.2±3.6

>Guar Gum 2.5 90.5±1.7 28.3±5.6

>5.0 82.5±6.3 25.6±1.3

>Locust bean gum 2.5 81.9±6.9 36.1±0.1

>5 85.4±8.2 34.3±0.7

>Pea fibre 2.5 92.0±3.2 44.5±2.5

>5 88.5±1.4 40.3±2.4

>

>This reduction in reducing sugar release following diges-

>tion,and the extent of starch degradation results in a reduc-

>tion in the predicted glycaemic index (PGI)of such foods.

>Table 2 illustrates the potential use of DF ingredients in

>manipulating the PGI of common foods.As can be seen

>from these values,the soluble DFs (guar and locust bean

>gum)appear to decrease the PGI value of these carbohy-

>drate-rich foods to a larger extent than the insoluble DF

>(pea fibre).What is of interest is the difference in the

>degree of PGI reduction between food products using the

>same DF source.Thus,a 2.5 and 5%addition of guar gum

>to bread reduces the PGI value by 4 and 13%,respectively,

>whereas a 2.5 and 5%addition of guar gum to pasta elicits a

>37 and 43%reduction in PGI,respectively.This indicates

>that the response of DFs in reducing the GI of foods may be

>process/product dependent.

>Scanning electron microscopy (SEM)images of pasta and

>bread samples before and after digestion clearly illustrate

>the possible influence DF additions have in altering food

>structure,and subsequently the influence that food structure

>has on the digestibility of starch.For instance,Fig.3 illus-

>trates the effect of a 10%guar inclusion on bread structure

>before (Fig.3b)and after (Fig.3d)a 300 min in vitro diges-

>tion process.Note that the control bread sample before

>digestion (Fig.3a)shows a porous structure in which indi-

>vidual starch granules are embedded in a glutinous protein

>matrix,whereas the sample with added guar (Fig.3b)is

>less defined,with protein,DF,and starch in a dense contin-

>uous network.This may be a result of the gelation charac-

>teristics of the soluble fibre used in this experiment.It is

>interesting to observe that this dense continuous network is

>still retained in the added fibre bread sample,even after 300

>min ingestion (Fig.3d),with starch granules seemingly

>engulfed in a gelatinous matrix.However,the control bread

>sample (Fig.3c)shows evidence of enzymic digestion,

>with the majority of its structure degraded.

>The striking effect of the DF on food structure and starch

>digestibility may in part be related to the theory on

>,thermodynamic incompatibility ’of biopolymers as pro-

>posed by Tolstoguzov [54,55 ].The thermodynamic incom-

>patibility theory describes the basis by which biopolymers

>show a preference to be surrounded by their own type in

>mixed solutions.For instance,Tolstoguzov [54,55 ]notes

>that amylopectin is incompatible with guar gum.Thus,if

>guar gum is added to a starch-rich matrix,it can lead to

>phase separation,and an encapsulation of the starchy phase

>by the guar gum-enriched phase.This encapsulation may

>then lead to impaired starch gelatinisation and hence degra-

>dation (as observed in Fig.2 and 3).

>The in vitro results shown above are in agreement with

>those of other in vitro [36 ]and in vivo experiments on the

>GI of foods. ...

>

>Al Pater, PhD; email: old542000@...

>

>

>

>

[Guest guest]

Hi All,

It seems to be so. See:

Eur J Nutr. 1999 Dec;38(6):278-85.

Dietary fiber reduces the antioxidative effect of a carotenoid and

alpha-tocopherol

mixture on LDL oxidation ex vivo in humans.

Hoffmann J, Linseisen J, Riedl J, Wolfram G.

BACKGROUND: Antioxidant concentrations in low density lipoproteins (LDL) are an

important determinant for their susceptibility to oxidation and can be modulated

by

dietary intake. AIM OF THE STUDY: In the present study, the influence of dietary

fiber on the antioxidant enrichment and the oxidation resistance of LDL after

antioxidant supplementation is investigated. METHOD: An antioxidant supplement

consisting of beta-carotene, lycopene, lutein, canthaxanthin and

alpha-tocopherol

was given to six young women together with a standard meal. Using a cross-over

study

design, each subject received the standard meal without additional dietary fiber

and

enriched with pectin, guar, or cellulose in a random order. To determine the

resistance of LDL against copper ion-induced oxidation, the formation of

conjugated

dienes was measured. RESULTS: Eight, 10, and 24 hours after antioxidant

supplementation the isolated LDL revealed significantly (p < 0.05) increased

antioxidant concentrations; addition of pectin, guar, or cellulose to the meal

depressed this increase. Concomitantly, the observed increase in the resistance

of

LDL against oxidation (measured as lag phase) was lower with dietary fiber

supplementation than that found without. On average, pectin, guar, and cellulose

reduced the increase of the lag phase (measured without addition of dietary

fiber)

by 38%, 22%, and 18%, respectively. CONCLUSIONS: These results indicate that

dietary

fiber supplementation decreases the antioxidative effect of a supplement

consisting

of carotenoids and alpha-tocopherol in LDL, an effect that is likely to be

mediated

by a reduced bioavailability of these antioxidants in the gut.

PMID: 10784384

--- apricot85 <apricot85@...> wrote:

> This seems to say that guar gum alters food structure & lessens it's

> access to digestive enzymatic activity. They mention only amylase, but

> could there be others? This must be why some users report weight loss. I

> wonder if this is something to be cautious about. I hope not because I

> love the improved glycemic control that I feel from using guar gum.

>

> Al Pater wrote:

>

> >Guar gum and glycemia

> >Hi All,

> >

> >The below excerpts from the available pdf for the Medline citation appear to

> indicate that guar gum is superior to insoluble and other soluble fiber and

highly

> effective for reducing the glycemic response to different

carbohydrates-containing

> foods. It seemed that the effectiveness was much greater on a percent basis

for

> the pasta versus the bread for guar gum reducing the glycemic response.

> >

> >Brennan CS.

> >Dietary fibre, glycaemic response, and diabetes.

> >Mol Nutr Food Res. 2005 Jun;49(6):560-70.

> >PMID: 15926145

> >

>

>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstr\

act & list_uids=15926145 & query_hl=77

> >

> >... 9 The physiological role of dietary fibre:

> >effect on the carbohydrate metabolism

> >DF has been shown to affect the rate and extent of starch

> >degradation.In particular,soluble DF has been shown to

> >reduce the rate of starch digestion and alter the rate of glu-

> >cose absorption [8,47 ].Research has concentrated on the

> >use of guar gum in food systems as a postprandial glucose

> >modifying ingredient [27 ].Similarly cellular components

> >of cereal grains,such as oat b -glucan gum,have been shown

> >to have nutritional benefits [48 –50 ].

> >The viscosity-altering behaviour of these soluble DFs

> >within the small intestine must account for some of these

> >effects,however,the DFs also appear to alter the structure

> >of the foods and hence the accessibility of the starch gran-

> >ules to the amylase enzymes [27,51 ].For instance,a range

> >of DFs (insoluble and soluble)have been used in the pro-

> >duction of pasta and bread.In vitro starch degradation of

> >these products has shown that the addition of DF has an

> >effect in reducing the amount of glucose produced follow-

> >ing digestion with amylase [51 –53 ].This reduction in glu-

> >cose can not be explained just on the basis of the DF exert-

> >ing a dilution factor on the starch component of the food.

> >Determination of residual starch following digestion indi-

> >cates that soluble fiber (such as inulin)additions to pasta

> >(Fig.2)significantly reduces the amount of starch digested

> >over a 300 min period.In many cases the magnitude of this

> >response is a direct function of dose.

> >

> >Table 2. Predicted GI values of cereal foods following addition of soluble

and

> >insoluble DFs

> >--------------------------

> >-------------Dietary fibre added

> >Type-----Amount Bread PGI Pasta PGI

> >-----------------------------

> >Control 0.0 94.4±1.6 45.2±3.6

> >Guar Gum 2.5 90.5±1.7 28.3±5.6

> >5.0 82.5±6.3 25.6±1.3

> >Locust bean gum 2.5 81.9±6.9 36.1±0.1

> >5 85.4±8.2 34.3±0.7

> >Pea fibre 2.5 92.0±3.2 44.5±2.5

> >5 88.5±1.4 40.3±2.4

> >

> >This reduction in reducing sugar release following diges-

> >tion,and the extent of starch degradation results in a reduc-

> >tion in the predicted glycaemic index (PGI)of such foods.

> >Table 2 illustrates the potential use of DF ingredients in

> >manipulating the PGI of common foods.As can be seen

> >from these values,the soluble DFs (guar and locust bean

> >gum)appear to decrease the PGI value of these carbohy-

> >drate-rich foods to a larger extent than the insoluble DF

> >(pea fibre).What is of interest is the difference in the

> >degree of PGI reduction between food products using the

> >same DF source.Thus,a 2.5 and 5%addition of guar gum

> >to bread reduces the PGI value by 4 and 13%,respectively,

> >whereas a 2.5 and 5%addition of guar gum to pasta elicits a

> >37 and 43%reduction in PGI,respectively.This indicates

> >that the response of DFs in reducing the GI of foods may be

> >process/product dependent.

> >Scanning electron microscopy (SEM)images of pasta and

> >bread samples before and after digestion clearly illustrate

> >the possible influence DF additions have in altering food

> >structure,and subsequently the influence that food structure

> >has on the digestibility of starch.For instance,Fig.3 illus-

> >trates the effect of a 10%guar inclusion on bread structure

> >before (Fig.3b)and after (Fig.3d)a 300 min in vitro diges-

> >tion process.Note that the control bread sample before

> >digestion (Fig.3a)shows a porous structure in which indi-

> >vidual starch granules are embedded in a glutinous protein

> >matrix,whereas the sample with added guar (Fig.3b)is

> >less defined,with protein,DF,and starch in a dense contin-

> >uous network.This may be a result of the gelation charac-

> >teristics of the soluble fibre used in this experiment.It is

> >interesting to observe that this dense continuous network is

> >still retained in the added fibre bread sample,even after 300

> >min ingestion (Fig.3d),with starch granules seemingly

> >engulfed in a gelatinous matrix.However,the control bread

> >sample (Fig.3c)shows evidence of enzymic digestion,

> >with the majority of its structure degraded.

> >The striking effect of the DF on food structure and starch

> >digestibility may in part be related to the theory on

> >,thermodynamic incompatibility ’of biopolymers as pro-

> >posed by Tolstoguzov [54,55 ].The thermodynamic incom-

> >patibility theory describes the basis by which biopolymers

> >show a preference to be surrounded by their own type in

> >mixed solutions.For instance,Tolstoguzov [54,55 ]notes

> >that amylopectin is incompatible with guar gum.Thus,if

> >guar gum is added to a starch-rich matrix,it can lead to

> >phase separation,and an encapsulation of the starchy phase

> >by the guar gum-enriched phase.This encapsulation may

> >then lead to impaired starch gelatinisation and hence degra-

> >dation (as observed in Fig.2 and 3).

> >The in vitro results shown above are in agreement with

> >those of other in vitro [36 ]and in vivo experiments on the

> >GI of foods. ...

> >

> >Al Pater, PhD; email: old542000@...

> >

> >

> >

> >

>

>

>

>

>

>

>

>