The Dose Response Effects of Partially Hydrolyzed Guar Gum on Gut Microbiome of Healthy Adults

Abstract

Background: Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic fiber that is used in foods and supplements. The effects of PHGG and its role in gut health are still being studied. The purpose of this study was to evaluate changes in the gut microbiome composition of healthy individuals in response to low-dose PHGG supplementation compared with a low fiber diet. Methods: A randomized, double-blind, placebo-controlled crossover study was performed on 33 healthy subjects (17 male, 16 female). Each subject completed three 14-day treatment periods with a 2-week washout between each period. Treatments included supplementation with 3 g PHGG, 6 g PHGG, or placebo. During all periods, the participants followed a low fiber diet (<14 g/day). Stools were collected on days 0 and 14 of each period. Gut microbiome profiling was performed using 16S rRNA sequencing. Results: Supplementation of 3 g and 6 g PHGG significantly increased Verrucomicrobia on day 14 when compared to the placebo (p=0.0066 and p= 0.0068, respectively). On the genus level, Akkermansia was significantly increased on day 14 with both the 3 g and 6 g PHGG doses (p=0.0081 and p=0.0083). Faecalibacterium was significantly decreased on day 14 with 3 g PHGG (p=0.0054). Conclusion: Supplementing with low doses of PHGG has the potential to cause shifts in gut microbiome composition. By increasing beneficial microbes, PHGG can improve the microbiome composition of healthy individuals and may play a role in the treatment of inflammatory gastrointestinal diseases.

Full text

Article Not peer-reviewed version
The Dose Response Effects of Partially
Hydrolyzed Guar Gum on Gut
Microbiome of Healthy Adults
Megan Edelman , Qi Wang , Rylee Ahnen , Joanne Slavin *
Posted Date: 17 January 2024
doi: 10.20944/preprints202401.1024.v1
Keywords: dietary fiber; PHGG; gut microbiome; soluble dietary fiber
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Article
The Dose Response Eects of Partially Hydrolyzed
Guar Gum on Gut Microbiome of Healthy Adults
Megan Edelman, Qi Wang, Rylee Ahnen and Joanne Slavin
Department of Food Science and Nutrition at the University of Minnesota
* Correspondence: jslavin@umn.edu
Abstract: Background: Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic ber that is used
in foods and supplements. The eects of PHGG and its role in gut health are still being studied. The purpose
of this study was to evaluate changes in the gut microbiome composition of healthy individuals in response to
low-dose PHGG supplementation compared with a low ber diet. Methods: A randomized, double-blind,
placebo-controlled crossover study was performed on 33 healthy subjects (17 male, 16 female). Each subject
completed three 14-day treatment periods with a 2-week washout between each period. Treatments included
supplementation with 3 g PHGG, 6 g PHGG, or placebo. During all periods, the participants followed a low
ber diet (<14 g/day). Stools were collected on days 0 and 14 of each period. Gut microbiome proling was
performed using 16S rRNA sequencing. Results: Supplementation of 3 g and 6 g PHGG signicantly increased
Verrucomicrobia on day 14 when compared to the placebo (p=0.0066 and p= 0.0068, respectively). On the genus
level, Akkermansia was signicantly increased on day 14 with both the 3 g and 6 g PHGG doses (p=0.0081 and
p=0.0083). Faecalibacterium was signicantly decreased on day 14 with 3 g PHGG (p=0.0054). Conclusion:
Supplementing with low doses of PHGG has the potential to cause shifts in gut microbiome composition. By
increasing benecial microbes, PHGG can improve the microbiome composition of healthy individuals and
may play a role in the treatment of inammatory gastrointestinal diseases.
Keywords: dietary ber; PHGG; gut microbiome; soluble dietary ber
1. Introduction
As changes in the gut microbiome and their relationship to human health are continuously
studied, many dierent types of pre- and probiotics have emerged as potential modulating agents. It
is well known that soluble ber has the ability to fuel changes to the composition of the gut
microbiome, and a variety of such bers have been explored in research to determine the extent of
change they may be able to produce and the dose that may be required to eect that change. Partially
hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic ber that has been of interest over the
years due to its potential to cause shifts in bacterial taxa that may be benecial to human health [1].
Guar gum is derived from the seeds of the guar plant (Cyamopsis tetragonolobus), and for many
years, it has been safely used as a food additive for thickening and stabilization [1]. Beyond its use in
food products for these purposes, guar gum has also been found to carry properties benecial to
human health, such as blood lipid-lowering eects and potential glycemic control for individuals
with type 2 diabetes mellitus [2, 3]. However, because guar gum itself is highly viscous and gel-
forming, it tends to be less appealing than other bers when added to certain foods or when taken as
a supplement.
Partial hydrolysis of guar gum creates a much less viscous ber, PHGG, that is preferable to
traditional guar gum for use as a dietary supplement for a number of reasons. Because PHGG is less
viscous and non-gelling, it is more palatable than guar gum when added to foods [1, 4]. PHGG also
ferments to a lesser degree than other types of soluble ber, making it less likely to cause the
undesirable GI symptoms traditionally associated with use of ber supplements, such as gas and
bloating [4].
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2
Several studies have analyzed the eects of PHGG on individuals with GI disorders, including
irritable bowel syndrome (IBS) [5, 6, 7]. Because PHGG stimulates the production of Bidobacteria
and short chain fay acids (SCFAs), such as butyrate, it may be used to improve the gut bacterial
environment of those with dysbiosis [8, 9, 10, 11, 12].
PHGG has also been studied for its ability to relieve constipation [5, 13, 14, 15, 16]. Constipation
remains a prevalent issue in both children and adults, and a key factor that many aribute to this
high prevalence of constipation is the historically low ber consumption in the majority of the US
population [17]. These studies found that PHGG alleviated constipation in subjects and conferred
additional benets to subjects, such as increasing the frequency of bowel movements [15], improving
stool consistency [15, 16], and relieving abdominal pain [16].
While existing studies largely support the hypothesis that PHGG can positively inuence the
gut microbiome composition of individuals with GI disorders and help to alleviate the symptoms
associated with those disorders, questions remain about the impact PHGG may have on the gut
microbiome of healthy individuals. Some studies have sought to answer this question however,
current research is limited [8, 10, 11, 18]. This lack of research leaves open the door to further explore
microbial changes in the gut as a result of PHGG intake and any possible associated physiological
benets. Therefore, this study aimed to explore the eects of 2 weeks supplementation of low-dose
PHGG on the gut microbiome of healthy individuals in comparison with a low-ber diet.
2. Materials and Methods
2.1. Participants
This study was a randomized, placebo-controlled, double-blind dietary intervention study
conducted at the University of Minnesota, registered at clinicaltrials.gov as NCT03722862. The trial
was conducted between April and September of 2019. 47 subjects were initially screened with, 33
healthy adult volunteers (17 male, 16 female) between the ages of 20 and 49 meeting eligibility
requirements and choosing to participate in the study.in this study. Subjects were recruited by phone
to determine their eligibility. Those who met eligibility requirements were invited to participate in
the study. Inclusion criteria included a BMI of >18.5 and <30 kg/m2, weight stable for the last 6 months,
no pre-existing health conditions that would prevent the subject from fullling the study, and a low
ber consumer (<14 g/day). In addition, the subject had to be willing to stick to their normal habitual
diet, excluding the consumption of any energy-rich or fat-rich meals or prolonged fasting throughout
the duration of the study. They were expected to maintain habitual physical activity paerns during
the study period and be willing to follow study procedures and dietary restrictions. Participants
completed a food frequency questionnaire of common high-ber foods, administered by research
sta, to determine subject baseline ber intake. Subjects were excluded from the study if they met
any of the following exclusion criteria:
• History of a gastrointestinal disorder
• Lactose intolerant
• High fiber consumer (≥15 g per day)
• Use of pre-and probiotics in the past 90 days
• High protein consumer (i.e. vegetarians or those who follow diets high in protein such as paleo)
• History of psychological illness or conditions that may interfere with subjects ability to
understand study directions
• Use of antibiotics or signs of active systemic infection in the last 6 months. Subjects who are on
hypo/hypercaloric diet aiming for weight loss or weight gain
• History or presence of cancer in the prior 2 years (except for non-melanoma skin cancer).
• Currently pregnant, lactating or planning to be pregnant during the study period
• Regular use of dietary supplements (ex: fish oil, riboflavin, etc.), 90 days prior to study
inclusion
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• Exposure to any non-registered drug product within the last 30 days prior to screening visit
• History of or strong potential for alcohol or substance abuse (within 12 months of screening
visit). Alcohol abuse is defined as >60g (men)/40g (women) pure alcohol per day (1.5 L/ 1 l beer
resp. 0.75l/0.5l wine).
• Current smoker or use of tobacco products in the past 90 days
• Concurrent or recent participation (30 days) in a dietary intervention trial
All research was conducted following the ethical principles for medical research involving
human subject set forth in the Helsinki Declaration. Wrien consent was obtained from all
participating study subjects, and all study protocols were submied to and approved by the
University of Minnesota Institutional Review Board (Study CON000000074233).
2.2. Material and Characteristics
A commercial formulation of PHGG (Sunber) was used as the treatment in this study. Previous
studies have used doses between 5 and 10 g PHGG and found positive eects on the gut microbiome
and on IBS symptoms [8, 11, 13, 18, 19]. Dosages of 3 g PHGG and 6 g PHGG were chosen for this
study with the intention of discovering if low doses of PHGG are capable of producing similar eects
in healthy individuals. The placebo was maltodextrin. Both PHGG treatments and the placebo were
in powdered form to be mixed with water or any non-alcoholic beverage for consumption. Subjects
were not instructed on any specic liquid to mix the treatment, but were advised that that carbonated
beverages were more dicult to mix with.
2.3. Supplementation and dosages
Subjects completed all three treatments throughout the duration of the study, including daily
dietary supplementation of 3 g PHGG, 6 g PHGG, and a placebo. All treatments were provided in
plain packaging, labeled only with “A,” “B,” or “C” to indicate which study arm the treatment belong
to. The 3 g PHGG treatment was combined with 3 g maltodextrin, and the placebo contained 6 g
maltodextrin, so the weights of the packages were equivalent for all treatments. Subject were
instructed to consume one package daily, mixed with water or another beverage. Subjects were
instructed to consume their daily treatment at a consistent time throughout each treatment period.
During the study period, subjects were asked to continue with their usual diet and to avoid prolonged
fasting or unusual consumption of any high-energy, high-fat, or high-ber meals. To ensure
participants did not change their regular food intake paern, food diaries were collected with 24-
hour food records from the subjects on days 1, 7, and 14 of each treatment.
2.4. Study Design and Protocol
The study performed was a randomized, double-blind, placebo-controlled, crossover study.
Three treatment periods of 14 days each were separated by two 14-day washout periods. Participants
were randomly allocated to study arms where each arm consists of a sequence of three treatments
given consecutively. Randomization was stratied by gender. For each of the three treatment arms,
subjects collected stool samples at Baseline (Day 0) and on the nal two days of treatment (Day 13,
Day 14), with subjects being asked to submit the nal stool sample they were able to collect from
either day for analysis.
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Figure 1. Timeline of PHGG treatment delivery and washout periods.
2.5. 16S rRNA Sequencing
16S ribosomal RNA sequencing was performed for analysis of gut microbiome composition. This
method serves as an ecient and cost-eective means to visualize changes in gut bacteria [20].
Current technologies for 16S rRNA sequencing constitute the most widely accepted and functional
method for evaluating gut microbial diversity [21]. 16S analysis was completed using the following
steps:
Sample Processing: Samples were boiled to lyze bacteria, and ethanol was added to the
preservative binding buer to a nal concentration of 30%. The total volume was placed on a silica
column to bind DNA, and washed 2x. Final elutions of DNA were carried out using 40uL of water.
16S Sequencing: The libraries were prepared using illumina 16S Metagenomic Sequencing kit
(Illumina, Inc., San Diego, CA, USA) according to the manufacturer`s protocol. The V3-V4 region of
the bacterial 16S rRNA gene sequences were amplied using the primer pair containing the gene-
specic sequences and Illumina adapter overhang nucleotide sequences. Amplicon PCR was
performed to amplify the template out of input DNA samples. Briey, each 25 μL of polymerase
chain reaction (PCR) reaction contains 12.5 ng of sample DNA as input, 12.5 μL 2x KAPA HiFi
HotStart ReadyMix (Kapa Biosystems, Wilmington, MA) and 5 μL of 1 μM of each primer. PCR
reactions were carried out using the following protocol: an initial denaturation step performed at
95°C for 3min followed by 25 cycles of denaturation (95°C, 30 s), annealing (55°C, 30 s) and extension
(72°C, 30 sec), and a nal elongation of 5 min at 72°C. PCR product was then cleaned up from the
reaction mix with Mag-Bind RxnPure Plus magnetic beads (Omega Bio-tek, Norcross, GA). A second
index PCR amplication, used to incorporate barcodes and sequencing adapters into the nal PCR
product, was performed in 25 μL reactions, using the same master mix conditions as described above.
Cycling conditions were as follows: 95°C for 3 minutes, followed by 8 cycles of 95°C for 30”, 55°C for
30” and 72°C for 30”. A nal, 5 minutes’ elongation step was performed at 72°C. The libraries were
normalized with Mag-Bind® EquiPure Library Normalization Kit (Omega Bio-tek, Norcross, GA)
then pooled. The pooled library ~600 bases in size was checked using an Agilent 2200 TapeStation
and sequenced (2 x 300 bp paired-end read seing) on the MiSeq (Illumina, San Diego, CA).
Metagenomics Analysis: The Metagenomics workow on BaseSpace (Illumina) was used for
analysis of 16S ribosomal RNA. In MiSeq Reporter, a naïve Bayesian classier has been implemented
that has been optimized for Illumina paired-end reads [22]. Alalysis used the reference database from
the May 2011 release of the Greengenes 16S rRNA database. The main output of the workow is a
classication of reads at several taxonomic levels (kingdom, phylum, class, order, family).
2.6. Salivary cortisol
Salivary cortisol was measured as a secondary objective of this study to evaluate potential
connections between PHGG and stress. Previous studies have evaluated the eect of prebiotics on
depression, anxiety, stress, and sleep quality [23, 24, 25, 26]. While cortisol may be measured in the
blood, urine, or saliva, multiple studies have found salivary cortisol to be a noninvasive and eective
means of quantifying the stress response [24, 25]. Subjects were provided with simple collection kits
that included a sterile phial and funnel to simplify the collection of saliva. Upon entry to the study,
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5
subjects were given instructions on best practices for saliva collection including a recommended
saliva amount.
2.7. Bristol Stool Form Scale
The Bristol Stool Form Scale (BSFS) visually depicts and describes seven dierent levels, or types,
of stool ranging from hardest (type 1) to softest (type 7). Images with accompanying denitions were
used by research sta to match subject stool consistency to one of the descriptions listed [27]. Types
1-2 are more indicative of constipation, types 3-4 indicate normal stool consistency, and levels 5-7
indicate loose stools or diarrhea [28]. BSFS ratings were assigned to each stool by research sta
immediately upon receipt of each stool sample.
2.8. Statistical Analysis
Descriptive statistics were calculated and presented by treatment. Treatments were compared
using mixed-eects models (SAS Proc Mixed). Models included xed eects of sequence, period, and
treatment and a random eect of subject (nested within sequence) to account for the within-subject
correlation among repeated measurements. The interaction between treatment and period was tested
and was dropped from the model as it was not signicant. If the overall F test for the eect of
treatment was signicant, pairwise comparisons were conducted to examine which treatment is
dierent from which. No adjustment was made for multiple testing. Analyses were performed in SAS
version 9.4 (SAS Institute Inc, Cary, NC). P values of less than 0.05 were considered statistically
signicant.
3. Results
3.1. Microbiome Composition
For microbiome analysis, both the dierences between day 0 and day 14 for each treatment were
measured, as well as the dierences across treatments on day 14. The concentration of Verrucomicrobia
was signicantly greater with both 3 g and 6 g of PHGG supplementation on day 14 (p=0.0066 and
p= 0.0068, respectively), when compared with placebo. Verrucomicrobia was also signicantly
increased from day 0 to day 14 with 6 g PHGG compared to placebo (p= 0.0102). Notable changes on
the genus level were those of Akkermansia, Dorea, and Suerella. Akkermansia was signicantly
increased from day 0 to day 14 with 6 g PHGG (p=0.0116), and the concentration of Akkermansia was
greater on day 14 with both 3 g (p=0.0081) and 6 g (p=0.0083) PHGG supplementation compared to
placebo. Concentrations of Suerella and Dorea were signicantly less with 3 g and 6 g PHGG than
with placebo on day 14. Counts of Erysipelotrichi were signicantly decreased over the course of 14-
day supplementation with 6 g PHGG compared with placebo (p=0.0092). Finally, the concentration
of Faecalibacterium was decreased with 3 g PHGG, 6 g PHGG, and placebo, but the results were only
signicant with 3 g PHGG (p=0.0054).
Table 1. Signicant dierences in relative change between day 0 and day 14.
•
Mean Change (Day 0-Day 14)
p-value
•
Treatment 1
(6 g PHGG)
Treatment 2
(3 g PHGG)
Treatment 3
(Control)
• 1 vs
2
• 1 vs
3
• 2 vs
3
• Phylum Relative
Verrucomicrobia
• 0.0089 + 0.0324
• 0.0015 + 0.0258
• -0.0082 +
0.0318
• 0.01
02
• Class Relative
Verrucomicrobiae
• 0.0092 + 0.0328
• 0.0011 + 0.0256
• -0.0082 +
0.0322
• 0.00
92
• Order Relative
Verrucomicrobiales
• 0.0094 + 0.0335
• 0.0012 + 0.0262
• -0.0083 +
0.0328
• 0.00
93
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• Family Relative
• Verrucomicrobiaceae
• 0.0099 + 0.0357
• 0.0012 + 0.0278
• -0.0087 +
0.0347
• 0.01
08
• Genus Relative
Faecalibacterium
• -0.0166 +
0.0529
• -0.0371 +
0.0458
• -0.0014 +
0.0541
• 0.00
54
Oscillospira
• -0.0102 +
0.0345
• 0.0059 + 0.0247
• -0.0128 +
0.0340
• 0.03
74
• 0.01
56
Akkermansia
• 0.0094 + 0.0342
• 0.0015 + 0.0275
• -0.0083 +
0.0333
• 0.01
16
Table 2. Signicant dierences in counts change between day 0 and day 14.
•
Mean Change (Day 0-Day 14)
p-value
•
Treatment 1
(6 g PHGG)
Treatment 2
(3 g PHGG)
Treatment 3
(Control)
• 1
vs 2
• 1 vs 3
• 2 vs 3
• Class Counts
Erysipelotrichi
-92.5 + 429.2
9.8 + 134.0
143.3 + 463.1
• 0.0092
• Order Counts
Erysipelotrichales
-92.5 + 429.2
9.8 + 134.0
143.3 + 463.1
• 0.0092
• Genus Counts
Faecalibacterium
• -799.2 +
1831.6
• -1586.5 +
2504.4
• -37.1 +
2864.3
• 0.0090
3.2. Salivary Cortisol
No signicant dierences were observed between the mean change of salivary cortisol from day
0 to day 14 across treatments. However, salivary cortisol did decrease with 6 g PHGG (-85.68 + 681.4),
while it increased with both 3 g PHGG and placebo. Salivary cortisol was increased to a lesser degree
with 3 g PHGG (21.52 + 345.32) than with placebo (68.88 + 407.41), although not statistically
signicant.
3.3. Stool Consistency
Participants rated their stool consistency at the end of each 14-day treatment period using the
Bristol Stool Form Scale. Results are displayed in Table 5. With the 3 g PHGG treatment, the
percentage stools rated as “normal” on the BSFS was similar to subjects they were receiving the
placebo. However, when subjects were consuming 6 g PHGG, a greater percentage stools were rated
“normal” (50%) compared to both 3 g PHGG (36.4%) and placebo (39.4%).
Table 3. Rating of stool consistency for each treatment using the Bristol Stool Form Scale.
Type 1-2 (Constipation)
Type 3-4 (Normal)
Type 5-7 (Loose Stool)
Placebo
21.2%
39.4%
39.4%
3 g PHGG
21.2%
36.4%
42.4%
6 g PHGG
25%
50%
25%
3.4. Safety Aspects
No serious adverse events were reported during this study, suggesting PHGG is safe to
consume. This indicates that PHGG taken as a supplement in doses of 3 to 6 g will likely not cause
any adverse eects.
4. Discussion
Fibers and oligosaccharides are known to alter gut microbiota. While fructooligosaccharides
(FOS) and galactooligosaccharides (GOS) are generally the most well-studied, the search for which
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7
fermentable bers are most successful in changing the gut microbiota continues, as does determining
which microbial shifts are most linked to health outcomes [21]. Prebiotics are dened by the fact that
they are non-digestible, fermented by intestinal microbes, and that they stimulate changes in the
composition of gut bacteria to provide benets to the host. While all prebiotics are ber, not all types
of ber fall under the prebiotic category [29]. As PHGG has been shown to fuel positive changes to
the human gut microbiome, it functions under the umbrella of a prebiotic ber, along with FOS and
GOS [30]. Furthermore, it may be beer tolerated [7].
In the present study, both Verrucomicrobia and Akkermansia increased with PHGG
supplementation. The mucin-degrading microbe, Akkermansia muciniphila, is a bacteria of the phylum
Verrucomicrobia, and it is found in higher concentrations in healthy individuals [31, 32]. It has been
shown that the concentration of Verrucomicrobia present in individuals with obesity is lower [33], and
decreased concentrations of Verrucomicrobia may even serve as an indicator of insulin resistance or
Type 2 Diabetes (T2DM) [34]. In individuals with GI diseases, such as IBD, the abundance of A.
muciniphila was signicantly lower, suggesting the decreased concentration of this bacteria may
function as an indicator of dysbiosis [35, 36].
Conversely, Dorea and Suerella were both decreased in this study with PHGG consumption.
Dorea belongs to the Lachnospiraceae family, which have been shown to produce some benecial
metabolites [37]. However, increased Lachnospiraceae is also associated with certain diseases,
systemic inammation, and IBS [18]. Some studies have demonstrated how Dorea may support the
production of IFNγ, leading to increased inammation [38, 39]. Therefore, it is thought that lower
concentrations of Dorea may be important for beer health outcomes [18]. Suerella is another bacteria
whose abundance is correlated with IBD and inammation [40]. Increases in Erysipelotrichi were also
positively correlated with inammatory GI disorders and colorectal cancer, though more research
needs to be done to establish dierences between human and animal models [41, 42]. In this case, the
decreased presence of these microbes with PHGG supplementation in our study was likely a
benecial shift.
Faecalibacterium was decreased in our study with 3 g PHGG supplementation. Because of its anti-
inammatory properties and ability to produce butyrate, increased Faecalibacterium is largely
accepted as an indicator of a healthy gut. It also tends to be found in decreased concentrations in
individuals with inammatory GI diseases [43]. Results of a previous study, wherein subjects
consumed 5 g PHGG up to three times daily, showed a subsequent increase in the level of
Faecalibacterium [30]. This may suggest that higher doses of PHGG are needed to increase the
concentration of Faecalibacterium. Further research needs to be done to explore the impact of low dose
PHGG on Faecalibacterium.
Secondary measures of this study included stool consistency and salivary cortisol. Neither the
placebo or the 3 g treatment of PHGG showed an ecacy in improving stool consistency, but 6 g
PHGG supplementation did appear to result in improvement in stool rmness. Salivary cortisol was
decreased with 6 g PHGG supplementation, suggesting that PHGG may have a positive eect on the
body’s stress response. However, this poses an area of research that requires much further
exploration. Future studies should focus on specic measures of the gut-brain connection with PHGG
as a microbiome modulator. This includes determining the best methods for evaluating the eects of
PHGG and other probiotics on stress and mental health.
One major limitation of this study is the variability in subject diets and lifestyle factors beyond
the control of the research team. While participants were asked to complete a baseline dietary ber
intake questionnaire and keep a food diary to ensure their diet did not change dramatically
throughout the course of the study, it is impossible to control for diet. Beyond dierences in ber
consumption, other components of the diet may also inuence changes in the gut microbial
composition, which may not be fully accounted for [44]. Salivary cortisol was used in this study as a
measure of stress response. However, it is possible that urinary cortisol may be a beer measure, as
it more accurately reects cortisol levels in the blood. Values for salivary cortisol may also be aected
by the time of day the sample is taken, introducing the potential for skewed results [26].
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Because PHGG increased the concentration of benecial microbes in this study, such as
Verrucomicrobia and Akkermansia, it is possible that low doses of this prebiotic ber may be a potential
treatment option in the future for improving the gut microbiome composition of individuals with
inammatory GI diseases. Other types of soluble ber have been studied in respect to their use as a
method for managing GI disorders, such as IBS [45, 46, 47]. Similar to other bers, PHGG may work
to improve dysbiosis, while triggering less undesirable symptoms given its non-viscous, lower-
fermenting properties. Dose-response eects of PHGG should be further explored in respect to GI
disorders to determine the most eective dose for both benecial microbiome shifts and management
of symptoms.
The present study demonstrated that even small doses of PHGG, as lile as 3 g, can inuence
the composition of the human gut microbiome in healthy subjects, including positive shifts in
benecial microbes. Individual variability in the human gut microbiome poses challenges to
determining how selective changes to bacterial taxa may result in health outcomes. Additional
research should be focused on how changes in the gut microbiome composition are associated with
resulting GI symptoms and other physiological benets.
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