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Immune-modulatory effects of dietary Yeast Beta-1,3/1,6-D-glucan



Beta-glucans are a heterogeneous group of natural polysaccharides mostly investigated for their immunological effects. Due to the low systemic availability of oral preparations, it has been thought that only parenterally applied beta-glucans can modulate the immune system. However, several in vivo and in vitro investigations have revealed that orally applied beta-glucans also exert such effects. Various receptor interactions, explaining possible mode of actions, have been detected. The effects mainly depend on the source and structure of the beta-glucans. In the meantime, several human clinical trials with dietary insoluble yeast beta-glucans have been performed. The results confirm the previous findings of in vivo studies. The results of all studies taken together clearly indicate that oral intake of insoluble yeast beta-glucans is safe and has an immune strengthening effect.
R E V I E W Open Access
Immune-modulatory effects of dietary Yeast
Heike Stier
, Veronika Ebbeskotte
and Joerg Gruenwald
Beta-glucans are a heterogeneous group of natural polysaccharides mostly investigated for their immunological
effects. Due to the low systemic availability of oral preparations, it has been thought that only parenterally applied
beta-glucans can modulate the immune system. However, several in vivo and in vitro investigations have revealed
that orally applied beta-glucans also exert such effects. Various receptor interactions, explaining possible mode of
actions, have been detected. The effects mainly depend on the source and structure of the beta-glucans. In the
meantime, several human clinical trials with dietary insoluble yeast beta-glucans have been performed. The results
confirm the previous findings of in vivo studies. The results of all studies taken together clearly indicate that oral
intake of insoluble yeast beta-glucans is safe and has an immune strengthening effect.
Keywords: Insoluble yeast β-glucans, Immune system, Clinical trial
A well-functioning immune system is crucial for staying
healthy. Therefore, the potential of natural substances to
strengthen the immune system has long been the subject
of investigation. There are many synthetic and natural
preparations claiming to be immunomodulators. Prob-
ably the best known herbal preparations that exhibit ef-
fects on the immune system are preparations made from
Echinacea, Viscum (mistletoe), and Pelargonium. There
is, however, another very interesting and, by now, properly
investigated class of immunomodulators - the β-glucans.
Long before the substance class of β-glucans them-
selves were identified as immunomodulators, the benefi-
cial effects of β-glucan-containing mushrooms such as
Shiitake (Lentinus edodes) in Japan or Lingzhi (Gano-
derma lucidum) in China were utilized in the traditional
Oriental medicine for the strengthening of the bodys
immune system.
The research on β-glucans started in the middle of the
last century, when the immune-modulating effect of a
yeast insoluble fraction was first shown [1]. Later it was
demonstrated that the immunological activity of this
preparation derives from the β-(1,3)-D-glucans [2].
Most of our current knowledge on the health benefits
of β-glucans, the underlying mode of action, and its rela-
tionship to the structure of β-glucans was discovered
within the last 20 years (for review see [3,4]).
Meanwhile, more than 6000 publications investigating
the immune-modulating effects of β-glucans, such as
anti-inflammatory or antimicrobial abilities, have been
published [5]. Health effects were found not only in
humans but also in invertebrates, rodents, fishes as well
as farm animals such as cows or pigs (for review see [4]).
Further, numerous studies reported other health benefits
of β-glucans, including hepatoprotective, wound healing,
weight loss, antidiabetic and cholesterol lowering func-
tions (for review see [6,7]).
β-glucans are a heterogeneous group of natural poly-
saccharides, consisting of D-glucose monomers linked
by a β-glycosidic bond. They are important structural
elements of the cell wall or serve as energy storage in
bacteria, fungi including yeast, algae, and plants, while
they are absent in vertebrate and invertebrate tissue.
The individual glucose subunits are primarily linked ei-
ther by (1,3)-β,(1,4)-β,or(1,6)-βglycosidic bonds. In most
cases, β-glucans exhibit a uniformly constructed backbone
of various lengths with side-chains of D-glucose attached
by (1,4)-β,or(1,6)-βbindings.
However, not all β-glucans are able to modulate im-
mune functions. These properties mainly depend on the
* Correspondence:
analyze & realize GmbH, Waldseeweg 6, 13467 Berlin, Germany
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Stier et al. Nutrition Journal 2014, 13:38
primary chemical structure of the β-glucans. Cellulose for
example, a (1,4)-β-linked glucan, does not exhibit immune-
modulatory effects. In contrast, β-glucans derived from
fungi and yeast, which consist of a (1,3)-β-linked backbone
with small numbers of (1,6)-β-linked side chains, are essen-
tially known for their immune-modulating effects [8].
Apart from differences in the type of linkage and
branching, β-glucans can also vary in solubility, molecu-
lar mass, tertiary structure, degree of branching, polymer
charge and solution conformation (triple or single helix
or random coil). All these characteristics may influence
their immune modulating effects [9]. On the other hand,
the manufacturing process and, hence, the isolation
method impacts the structure of β-glucans and conse-
quentially their effects on the immune system. Indeed,
the immune-modulating activity of different β-glucans
from the same source might differ considerably in level
of purity, solubility, molecular mass, tertiary structure,
degree of branching, polymer charge and solution con-
formation [5].
Although there are numerous in vitro and in vivo in-
vestigations, human clinical trials confirming the pre-
clinical findings are rather scarce. Due to different
natural sources of the β-glucans, differences in application
(intraperitoneal, intravenous or subcutaneous injections,
or oral), differences in preparation and thus structural dif-
ferences, the results obtained in the resulting clinical stud-
ies are non-homogeneous and often contradictory [4].
Due to this heterogeneity, we focused our review
on the immune-modulating effects of insoluble yeast-
derived dietary β-glucans.
The main focus will be on the food product Yestimun® -
an insoluble, highly purified, well-characterized and in-
tensively studied β-glucan from Spent BrewersYeast.
The in vivo data obtained from this preparation, to-
gether with the efficacy results obtained during clinical
trials, will be presented and compared to the other dietary,
insoluble yeast β-glucan preparations available on the
market. Only randomized, controlled trials were consid-
ered for the purpose of this review. Possible mechanisms
of action will be presented, based on the current know-
ledge about structure-function relationships of β-glucans.
Studies investigating other aspects than the immune sys-
tem or studies with soluble β-glucans were excluded.
Characteristics of the proprietary yeast β-glucan
preparation (Yestimun®)
Yestimun® is an insoluble (1,3)-(1,6)-β-glucan made from
Spent BrewersYeast (Saccharomyces cerevisiae). The
brewersyeast used in Yestimun® is grown exclusively on
malt and clean spring water with no other nutrients
added. It is a natural by-product of the fermentation
process used for beer production. Following gentle au-
tolysis with the yeasts own enzymes, high-performance
centrifuges are used to separate the yeast autolysate into
the soluble yeast extract and the insoluble yeast cell wall.
Yeast cell walls contain typically about 30% of β-glucans
of dry weight. During several separation processes, the
β-glucans are further purified without the use of strong
alkaline in the hydrolysis process, and soluble com-
pounds are removed. Furthermore, the process does not
involve an acidic hydrolysis, leaving the acid-sensitive β-
1,6-glucan side chains mainly intact. This results in an
average of 22% relative linkage percentage from β-1,6
glucan (H-NMR analysis according to FCC VII, 3rd
suppl.; reference-glucan at 14%), with a minimum of
purity of 85% (dry mass).
Growth conditions of the yeast might result in some
heterogeneity of β-glucans within the cell wall [4].
Therefore, it can be speculated that β-glucans from cell
walls of S. cerevisiae grown during brewery have a differ-
ent β-glucan pattern than those from bakersyeast,
which might also influence the immuno-modulating
abilities of the product.
Mode of action/structure function relationship
As humans cannot metabolize the β-glycosidic bonds
from β-glucans, it has long been suspected that the bac-
terial fermentation process taking place within the intes-
tinal system is involved in the health promoting effect of
Meanwhile, different possible mechanisms have been
identified on how oral β-glucans modulate the immune
system (for review see [10,11]).
In general, humans cannot synthesize β-glucans. There-
fore, the immune system recognizes these compounds as
foreign. The innate immune system responds to invading
pathogens through pattern recognition receptors (PRR),
which are typically expressed by immune cells but also by
other cells. PRRs recognize conserved microbial struc-
tures, the so-called microbe-associated molecular patterns
(MAMPs) [12], formally called PAMPs [13,14]. β-glucans
are considered as one of the major MAMPs for the PRR-
mediated sensing of fungal infection. So far, the most im-
portant PRRs for β-glucans are the dectin-1 receptor, the
complement receptor 3 (CR3) and toll-like-receptors
(TLR), which are found on various immune cells such as
monocytes, macrophages, dendritic cells, neutrophils, eo-
sinophils, and natural killer cells, but also on intestinal
epithelial cells [10,15-17]. Binding of β-glucans to dectin-1
induced a cascade of innate and adaptive immune re-
sponse such as phagocytosis, oxidative burst, and the pro-
duction of cytokines and chemokines in dentritic cells and
macrophages [15]. Kankkunen et al. showed that particu-
late yeast β-glucan triggered interleukin-1β(IL-1β)medi-
ated cellular response in human primary macrophages via
dectin-1 signaling [18]. Earlier in vitro studies showed that
yeast β-glucan is a strong stimulant of macrophages [19]
Stier et al. Nutrition Journal 2014, 13:38 Page 2 of 9
and induced mitogenic activity in rat thymocytes, indicat-
ing immunostimulatory effects [20].
The exact mechanism on how β-glucans affect im-
mune function depends in part on the route of admin-
istration. Strong effects were already observed in
studies in the early 1990s using intravenously injected
yeast β-glucans [21-23], when the biological efficacy of
orally administered β-glucans was critically discussed.
In terms of oral administration, the impact on immune
function is assumed to be primarily explained by the
interaction of β-glucans with pinocytic microfold (M)-
cells located in the small intestine [24]. It has been sug-
gested that M-cells take up β-glucans and transport
them from the intestinal lumen to the immune cells lo-
cated within the Peyers patches [11].
Uptake of β-glucans has been shown in mice with sol-
uble and particulate yeast (1,3)-(1,6)-glucans labeled with
fluorescein. Both types of yeast β-1,3-glucans were taken
up by gastrointestinal macrophages, and then processed
forms were transported to the lymph nodes, spleen and
bone marrow [25]. Also, in vitro experiments have shown
that β-glucans were degraded inside macrophages and re-
leased into the culture medium [25], which makes them
eventually available for the circulating system and a sys-
temic distribution.
Orally administered β-glucans induced phagocytic activ-
ity, oxidative bursts, and IL-1 production of peritoneal
macrophages in mice [26]. A higher phagocytic activity
and oxidative metabolism of neutrophils and monocytes,
indicating an immune restoring activity of yeast β-glucan
has also been shown in rats [27]. However, not only the
cellular but also the humoral acute phase immune reac-
tion is affected by yeast β-glucan feeding as shown by in-
creased lysozyme and ceruloplasmin activitiy [28].
Moreover, oral delivery of β-glucans impact mucosal
immunity, as shown by an increase of intraepithelial
lymphocytes in the intestine of mice [29]. In rats, the ab-
sorption of soluble β-glucans translocated from the
gastrointestinal tract into the systemic circulation leads
to an increased immune response and resistance against
infectious challenge [16]. The effect of an insoluble β-
glucan against anthrax infection in mice showed that the
treated animals survived the anthrax infection, while
50% of the control animals died, indicating an improved
immune function in animals fed with β-glucan [30].
Another important aspect to be considered is the solu-
bility of β-glucans, as soluble and particulate (insoluble)
β-glucans isolated from yeast may stimulate the immune
system via different pathways [31]. In vivo and in vitro
studies revealed that particulate (insoluble) β-glucan was
phagocytosed by dendritic cells and macrophages via
dectin-1 receptor pathway. Although particulate β-glucans
can also be taken up by dendritic cells through a dectin-1
receptor independent mechanism, the dectin-1 receptor
pathway is essential for the activation of dendritic cells,
which in turn induces T-cell response and cytokine release
[31]. However, not all insoluble particulate β-glucans are
able to bind to and activate the dectin-1 receptor. Studies
with synthetically produced β-glucans revealed that bind-
ing to dectin-1 receptor is specific for β-glucans with a
(1,3)-beta backbone. Backbones with mixed (1,3)/(1,4)-β-
bindings (e.g. barley derived β-glucans) are not recognized
by this receptor. Also, a backbone length of at least seven
glucose units is required for binding, in addition to one
(1,6)-β-side-chain branch (e.g. insoluble yeast β-glucans).
Furthermore, the binding activity increases with increas-
ing molecular weight of the polymer [32]. However, bind-
ing to the dectin-1 receptor alone does not activate the
signal cascade induced by this receptor. Indeed, dectin-
1 signaling and the concomitant immune responses are
only activated by particulate β-glucans but not by sol-
uble β-glucans [33]. Insoluble, particulate β-glucans in-
duced the process of phagocytosis, resulting in the
elimination of invading microbes by binding to the
dectin-1 receptor [31]. Further, particulate β-glucans pro-
motes T-cell differentiation into Th1-cells and enhances
cytotoxic T lymphocyte priming by the dectin-1 pathway.
Even though soluble β-glucans are also recognized by the
dectin-1 receptors, they cannot activate immune response
via this pathway. Soluble β-glucans are, however, able to
bind to the CR3 receptor. The activation of the CR3 leads
to complement system mediated immune process, sup-
ported by specific antibodies [31].
These results show that different β-glucan particles in-
fluence the immune system via different pathways. Insol-
uble β-glucans are able to activate both the innate and the
adaptive immune responses, whereas soluble β-glucans
are most effective via the complement system, which
needs specific antibodies.
Studies performed with the proprietary yeast
β-glucan preparation (Yestimun®)
In vivo studies with Yestimun®
Feeding experiments with Yestimun® (previously called
Biolex-Beta HP) in rats [34] showed that β-glucans in-
creased the phagocytic activity of granulocytes and mono-
cytes and the percentage of phagocytic cells. β-glucan
feeding tended to have positive effects on the oxidative
metabolism of these cell types. After stimulating mono-
cytes with E. coli, the oxidative metabolism was signifi-
cantly higher in the β-glucan group. Comparable effects
were observed after phorbol myristate acetate (PMA)
stimulation, a strong respiratory-burst stimulus [34].
Application of the same orally applied insoluble β-glucan
resulted in an increase in non-specific humoral immune
parameters in rats as shown by higher lysozyme and ceru-
loplasmin activities and serum γ-globulin levels [28]. This
indicates that β-glucans may affect the synthesis of acute
Stier et al. Nutrition Journal 2014, 13:38 Page 3 of 9
phase proteins. When the blood phagocytic cells were ana-
lyzed for their respiratory burst activity and their potential
killing activity, the cells derived from the β-glucan fed
group showed higher activity. Also, the proliferation
rate of blood lymphocytes, when stimulated by Conca-
navalin A (ConA) or lipopolysaccharide (LPS), was higher
in the β-glucan group, also indicating effects of β-glucans
on cellular immunity [28].
These results were confirmed in another in vivo investi-
gation in rats with cyclophosphamide suppressed immune
systems [27]. Under these conditions, feeding β-glucans
led to an increased phagocytic activity of monocytes and
granulocytes. Also, the respiratory-burst activity and
the oxidative metabolism of granulocytes and monocytes
stimulated with formyl-Methionyl-Leucyl-Phenylalanine
(fMLP), PMA and E. coli was increased [27].
In a very recent investigation, the same β-glucan
preparation from Spent BrewersYeast was, for 42 days,
fed to dogs suffering from Inflammatory Bowel Disease
(IBD) [35]. Within this time, the animals treated with
β-glucan showed a significant improvement, measured
by the Canine Inflammatory Bowel Disease Acitivity
Index (CIBDAI). They further showed a decreased level
of the pro-inflammatory IL-6 and an increase of the
anti-inflammatory IL-10, as compared to untreated
control animals [35].
From these experiments (see Table 1), it may be con-
cluded that orally applied insoluble yeast β-glucans are
able to strengthen a weakened immune system.
Clinical trials performed with the proprietary yeast β-glucan
Susceptibility to common cold is related to a weak im-
mune status or a weak defense system. In the early
1990s, Cohen and colleagues demonstrated that the im-
mune status of people with a high susceptibility to com-
mon colds is affected by lifestyle factors such as stress,
emotional imbalance, mood, specific vitamin deficien-
cies, or exposure to wet conditions and low tempera-
tures, and that the susceptibility is correlated to the
occurrence of cold infections [36,37]. In contrast, a
lower susceptibility to cold episodes reflects an improved
defense against infections and, hence, a properly func-
tioning immune system. Therefore, common cold is
widely used as a proper model to investigate potential
immune-modulating properties of natural substances,
including β-glucans.
Two independent randomized, double-blind, placebo-
controlled clinical trials showed that daily oral adminis-
tration of the proprietary insoluble (1,3)-(1,6)-β-glucan,
derived from brewersyeast, reduced the incidence of
common cold episodes during the cold season in other-
wise healthy subjects [38,39] (see Table 2).
In the trial conducted by Graubaum et al. [39], 100
subjects received either the yeast-derived β-glucan
preparation (900 mg/day) or a placebo over a period of
26 weeks. Results showed that, compared to placebo,
more subjects in the intervention group did not have a
common cold infection at all. The β-glucan group had
significantly more subjects without a common cold epi-
sode than the placebo group. During the most intense in-
fection season, the β-glucan group had significantly less
infections compared to placebo. Ingestion of β-glucans
significantly reduced the typical cold symptoms [39].
The second trial with 162 participants confirmed these
results, as the number of cold episodes was reduced by
25% in the β-glucan group, compared to the placebo
group (p = 0.041) [38]. Moreover, the authors reported a
milder progression of severe common cold episodes in
subjects supplemented with β-glucans. Also, sleeping diffi-
culties, regarded as a side effect of a cold infection, were
improved by the supplementation of β-glucan (p = 0.028).
The results of the common cold studies in healthy
adults showed the immune-stimulating effects of the
same brewersyeast β-glucan preparation. As an immu-
nomodulator, however, β-glucans are also able to induce
anti-inflammatory abilities. Kohl et al. [40] showed an
anti-inflammatory action of the same β-glucan prepar-
ation in overweight and obese subjects. Obesity is often
associated with inflammatory conditions that lead to an
activation of the innate immune system. Long-term acti-
vation of the immune system may cause several other
health related problems, including insulin resistance [40]
(see Table 2). Indeed, yeast β-glucan consumption had
an impact on immune function, as shown by an increase
of both circulating levels and adipose tissue messenger
RNA (mRNA) expression of the anti-inflammatory cyto-
kine IL-10. Insulin sensitivity as well as circulating levels
and mRNA expression of pro-inflammatory cytokines
were, however, unaffected. The results indicate that
intake of particulated yeast β-glucans also has anti-
inflammatory properties.
These studies provide evidence on the potential
immunmodulatory effects of yeast β-glucans: On one
hand, the substances elicit/amplify (activate) the immune
reaction as shown in the prevention of infections; on the
other hand, they are capable of reducing the inflamma-
tory reaction by inducing anti-inflammatory processes.
The clinical findings confirmed the previous results of
the in vivo investigations performed with Yestimun® in-
vestigating the immunomodulatory effect (see Table 1).
Altogether, these in vivo studies, together with the hu-
man clinical trials, provide evidence on the substantial
biological relevance of the β-glucan preparation Yesti-
mun® on the immune system.
Clinical trials with other dietary yeast β-glucans
A search for other placebo-controlled human trials per-
formed with β-glucans derived from yeast (Saccharomyces)
Stier et al. Nutrition Journal 2014, 13:38 Page 4 of 9
in the field of respiratory tract infection or common cold
was performed in PubMed database. The main search
terms were controlled clinical trialAND, common cold
OR respiratory tract infectionin combination with β-glu-
can AND yeast. Apart from the clinical trials performed
with Yestimun®, we found nine other studies that fit our
search criteria [22,41-48]. The publications by Babineau
et al. [21] and Dellinger et al. [41] will not be discussed fur-
ther, since the β-glucans were applied intravenously and
not orally, to a group of high-risk surgical patients.
The following human studies were all performed with
the same insoluble bakersyeast β-glucan preparation
Wellmun WGP® (relative% of 1,6 linkage: 10%-18%; H-
NMR analysis according to FCC VII, 3rd suppl.; purity:
minimum of 75% of dry matter). In one intervention,
healthy community-dwelling subjects (n = 40) received
either an insoluble β-glucan preparation (500 mg/day) or
placebo. Intake of β-glucans did not result in any signifi-
cant difference in incidences of respiratory infections.
Even though the number of infections was not different,
none of the subjects supplemented with β-glucans
missed school or work due to colds as opposed to pla-
cebo [42].
Similar results were obtained when healthy individuals
(n = 79) received either 250 mg/day β-glucans or placebo
over a period of 90 days during the peak upper respira-
tory tract infection (URTI) season. Even though there
was no statistically significant difference in the total
Table 1 In vivo studies performed with the proprietary yeast β-glucan preparation Yestimun
Title/reference Study design/duration/dosage Main results
Effect of β-1,3/1,6-D-glucan on the phagocytic
activity and oxidative metabolism of peripheral
blood granulocytes and monocytes in rats [34]
20 adult rats were fed for 14 days with either
1219 mg/rat/day β-1,3/1,6-D-glucan
(Biolex-Beta HP*) or control diet
Arterial blood was analyzed for phagocytic activity
and oxidative metabolism in blood granulocytes
and monocytes:
significant higher phagocytic activity and a
significant higher percentage of phagocytic cells
in granulocytes and monocytes of β-glucan fed
positive effects on the oxidative metabolism of
these cell types
monocytes stimulated by E. coli showed
significantly higher oxidative metabolism in
the β-glucan group
Effect of Biolex β-HP on selected parameters
of specific and non-specific humoral and
cellular immunity in rats [28]
20 adult rats were fed for 14 days with
either 1219 mg/rat/day β-1,3/1,6-D-glucan
(Biolex-Beta HP*) or control diet
Orally applied insoluble β-glucans are able to
increase non-specific humoral immune
parameters in rats:
lysozyme and ceruloplasmin activities and serum
gamma-globulin levels were significant higher
significant higher respiratory burst activity and
potential killing activity of blood phagocytic cells
significant higher proliferation rate of blood
lymphocytes when stimulated by ConA or LPS
Effect of Biolex Beta-HP on phagocytic activity
and oxidative metabolism of peripheral blood
granulocytes and monocytes in rats intoxicated
by cyclophosphamide [27]
10 adult rats (control) and 10 rats treated with
cyclophosphamide were fed for 14 days with
β-(1,3)-(1,6)-D-glucan (Biolex-Beta HP*) at a dose
of 50 mg/kg body weight/day or control diet
Under the condition of an experimentally
suppressed immune system (treatment with
cyclophosphamide), feeding with β-glucan led to:
increase of percentage of phagocytic monocytes
and granulocytes
improvement of phagocytic activity of
monocytes and granulocytes
a high level of oxidative metabolism of
granulocytes and monocytes stimulated with
fMLP, PMA and E. coli
The effectiveness of natural and synthetic
immunomodulators in the treatment of
inflammatory bowel disease in dogs [35]
28 dogs with IBD were treated for 42 days with Feeding with β-glucan led to:
I) β-(1,3)-(1,6)-D-glucan (Biolex-Beta HP*) at a
dose of 7 mg/kg body weight/day
decrease of the IBD symptoms measured by IBD
Activity Index
II) β-hydroxy- β-metyl butyrate 30 mg/kg
decrease of the pro-inflammatory interleukin IL-6
III) levamisol 2 mg/kg bw/day increase of the anti-inflammatory interleukin IL-10
IV) control, without supplementation
*Yestimun® was previously called Biolex-Beta HP.
Stier et al. Nutrition Journal 2014, 13:38 Page 5 of 9
number of days with reported URTIs (β-glucans
198 days in 4.6%, versus 241 days in 5.5% in the control
group, p = 0.06), the symptoms tended to be lesser in
the β-glucan group. Of all assessed symptoms, only the
item ability to breathe easilywas significantly better
in the β-glucan group than in the placebo group [47].
The ability to minimize post-exercise-induced immune
suppression was measured in physically active subjects
(n = 60), who consumed either 250 mg insoluble β-glucans
or placebo (rice flour; cross-over design) for 10 days (pre-
exercise supplementation period) before a bout of cycling.
Blood analysis showed that ingestion of β-glucans signifi-
cantly increases the total number of monocytes as well as
of pro-inflammatory monocytes (p < 0.05). Further ex vivo
LPS stimulation significantly increased plasma cytokine
production of IL-2, Il-4, IL-5, and interferon-gamma [46].
These ex vivo results confirmed the results obtained
from marathon runners (n = 75), who randomly received
either 250 or 500 mg/day β-glucan or a placebo over
four weeks post-marathon [43]. Particulate β-glucans
significantly reduced URTI symptoms compared to pla-
cebo (p < 0.05). The number of URTI after four weeks
post-marathon in both β-glucan groups was reported to
be only 8% compared to 24% in the placebo group (not
Long-term stress is another factor known to weaken
the immune system. When stressed women (n = 77) took
insoluble bakersyeast β-glucan before breakfast for
12 weeks, they reported fewer upper respiratory tract
symptoms compared to placebo (p < 0.05) and a better
overall well-being (p < 0.05) [48]. Similar results have been
obtained in moderate to highly stressed subjects (n = 150;
placebo n = 50; 250 mg β-glucan/day n = 50; 500 mg
β-glucan/day n = 50) [44] as well as healthy stressed
subjects (screened for moderate level of psychological
stress n = 122) [45]. Once again, the subjects reported sig-
nificantly fewer URTI symptoms and improved well-being
(p < 0.05).
Although most of the trials mentioned above were
underpowered and the differences in number of infections
were not always significant compared to placebo, all are in
support of the positive effects of insoluble β-glucans on
the human immune system. The differences in the studies
conducted with different β-glucan preparations may be
explained by varying study conditions, sample size, study
populations, applied dosages, and the different sources or
Table 2 In vivo studies performed with the proprietary yeast β-glucan preparation Yestimun
Title/reference Study design/duration/dosage Main results
Increased interleukin-10 but unchanged
insulin sensitivity after 4 weeks of
(1, 3)(1, 6)-beta-glucan consumption
in overweight humans [40]
Randomized, double-blind, placebo-controlled,
crossover study;
In overweight or obese subject the orally applied
β-glucan leads to the following results:
12 healthy overweight and obese subjects
3 × 0.5 g of (1,3)(1,6)-D-glucan (Biolex-Beta
HP*) or placebo per day 2 × 4 weeks
significant increase of both circulating levels and
adipose tissue messenger RNA (mRNA) expression
of the anti-inflammatory cytokine IL-10
insulin sensitivity was unaffected
no increase in non specific proinflammatory
markers CRP, IL-6 and MCP-1/CCL-2
circulating levels and mRNA expression of
proinflammatory cytokines were unaffected
A double-blind, randomized, placebo-controlled
nutritional study using an insoluble yeast
beta-glucan to improve the immune defense
system [39]
Randomized, double-blind, placebo-controlled
clinical trial;
Supplementation with 1,3/1,6-D-glucan led
compared to placebo to:
100 healthy adults with recurring common
colds received 1,3/1,6-D-glucan (Yestimun®)
900 mg/day or a placebo for 26 weeks
significant more subjects without incidences of
common cold
significant less infections during the most intense
infection season
significant reduction of the typical cold symptoms:
sore throat and/or difficulty swallowing,
hoarseness and/or coughand runny nose
Yeast (1,3)-(1,6)-beta-glucan helps to maintain
the bodys defense against pathogens: a
double-blind, randomized, placebo-controlled,
multicentric study in healthy subjects [38]
Randomized, double-blind, placebo-controlled
clinical trial;
Supplementation with 1,3/1,6-D-glucan led
compared to placebo to:
162 healthy adults with recurring common
colds received 1,3/1,6-D-glucan (Yestimun®)
900 mg/day or a placebo for 16 weeks
a significant reduced number (by 25%) of
common cold infections in the per protocol
a 15% lowered mean symptom score
significant reduced sleep difficulties usually
caused by common cold episodes
*Yestimun® was previously called Biolex-Beta HP.
Stier et al. Nutrition Journal 2014, 13:38 Page 6 of 9
isolation methods of β-glucan from brewersyeast or
These clinical trials were all performed with insoluble
yeast β-glucans. Only one human clinical trial investigat-
ing the immune effect of dietary soluble yeast β-glucans
has been found [49]. In that pilot trial, dietary intake of
soluble β-glucans leads to an increase in salvia IgA
concentration. Based on this pilot trial it is not pos-
sible to come to a final conclusion that also soluble
yeast β-glucans, when applied orally, are able to
strengthen the immune system the way it was shown
for the insoluble yeast β-glucan fraction.
Even though many of the clinical trials performed with
insoluble β-glucan preparations showed positive effects
on the immune system, none of them were so far able to
convince the European Food Safety Authority (EFSA) to
accept a health claim application in the area immune
system. EFSA rejected all generic claim applications
(13.1 claims) regarding beta-glucan and immune func-
tion. Also, the two product-specific 13.5 health claims
submitted for the product Yestimun® were rejected
[50,51]. The Panel concluded that a cause and effect re-
lationship has not been established. The major reasons
for rejection in those cases were the use of a non-
validated questionnaire on common cold as well as limi-
tations of the statistical analysis. However, EFSA has not
granted any of the applications for product-specific 13.5
health claims on immune function. Only generic 13.1
claims for vitamins and minerals have been accepted
[52,53]. These numerous rejections indicate the very
high benchmark demanded by EFSA for claim substanti-
ation on immune function.
Brewersand bakersyeast (S. cerevisiae) has a long his-
tory of safe consumption. It has been used for over a
thousand of years in the production of bread, wine, and
beer. Although allergies to S. cerevisiae from food con-
sumption might occur [54], they are rare. In general,
yeast products are very well tolerated. However, no stud-
ies addressing the beneficial as well as adverse effects
due to long-term intake of β-glucans are available as
yet. In a scientific opinion, the EFSA Panel on Dietetic
Products, Nutrition and Allergies (NDA) considered
that the allergenic risk of the yeast β-glucansis not
higher than the risk from other products containing
bakersyeast. β-glucans from other sources have already
been evaluated for safety by EFSA[55]. The result of
the EFSA evaluation is, among others, based on the sig-
nificant history of safe use of yeast and on data from
human and animal studies.
In the above-presented human studies with orally ap-
plied yeast β-glucans, no signs of toxicity were reported.
In all these clinical trials, insoluble yeast β-glucans were
very well tolerated. When adverse events occurred, they
were either not associated with the intake of the study
products, or they were comparable to the intake of
Single-dose acute and sub-chronic toxicity studies in
rats did not result in toxic effects of insoluble bakers
yeast (S. cerevisiae) preparations. Single dosages of
2000 mg/kg did not lead to death or clinical abnormal-
ities in any of the tested rats. Also, oral application over
91 days of up to 100 mg/kg body weight did not lead to
adverse or toxic effects in rats [56].
In some publications, insoluble β-glucans are stated to
exhibit undesirable toxicological effects such as hepatos-
plenomegaly and granuloma formation. However, these
adverse reactions were only associated with intravenous
application [57,58]. Such adverse events never have been
reported after oral application.
The safety of β-glucans can also be deduced from the
mode of action. β-glucans do not directly attack the in-
fected cells or the infection causing agents, but instead
modulate the hosts defense mechanism. For example,
macrophages were activated, but only reacted if foreign
cells (bacteria, viruses, parasites) invade the system.
Many investigations on the immunomodulatory effects
of β-glucans were performed using parenteral applica-
tions. In the meantime, those effects have also been
shown for orally applied β-glucans. Therefore immune
stimulating effects may be achieved by dietary intake
of yeast β-glucans. Despite those positive effects the
European Food Safety Authority did not accept health
claim applications of β-glucans in the area immune sys-
tem. Based on several weaknesses regarding study design
and statistical evaluations the panel concluded that a
cause and effect relationship has not been established.
β-glucans from yeast are recognized by immune cells
within the intestinal mucosa, amongst others by the
dectin-1 receptor. Dectin-1 receptor activation induces
several immune-stimulating effects important in the
defense against invading pathogens. Furthermore, follow-
ing uptake of β-glucans via dectin-1-stimulated phagocyt-
osis, degradation processes within macrophages may make
β-glucans systemically available.
However, not all β-glucan preparations have the po-
tential to stimulate these reactions. In order to be able
to activate the dectin-1 receptor cascade, β-glucans must
comply with specific structural properties. It seems that
insoluble, particulate (1,3)-β-glucans with 1,6-β-branches
are able to activate this cascade, while soluble ones acti-
vate the antibody-mediated complement system via the
CR3 receptor.
Clinical trials performed with dietary insoluble par-
ticulate β-glucans have demonstrated positive effects on
Stier et al. Nutrition Journal 2014, 13:38 Page 7 of 9
the immune system. Therapeutic efficacy results for or-
ally applied soluble yeast β-glucans are not yet avail-
able. Whether or not the soluble fraction of the yeast
β-glucan, when orally applied, is equally active when in-
fluencing the human immune system needs to be
proven in confirmative clinical trials. So far, this has
only been shown for the insoluble fraction.
All the performed human clinical trials demonstrated
that intake of β-glucans isolated from brewersyeast is
very well tolerated. Based on the clinical trials presented
in this review, an increased intake of dietary β-glucans
might help to improve immune functions.
Competing interests
This work has been funded by Leiber GmbH (Bramsche, Germany), the
manufacturer of the yeast β-glucan preparation Yestimun®. VE is an
employee of Leiber GmbH; HS and JG are employees of the contract
research organization (CRO) analyze & realize GmbH, and where previously
involved in the publication of two clinical trials with Yestimun®.
HS has drafted and written the manuscript. VE and JG have been involved in
drafting the manuscript and revising it critically for important intellectual
content. All authors read and approved the final manuscript.
HS is working as a Scientific Consultant for the CRO analyze & realize GmbH
(Germany); JG is the founder of the CRO analyze & realize GmbH (Germany).
VE is working as a scientist in the technical service of the animal nutrition
department of Leiber GmbH (Bramsche, Germany).
We thank I. Wohlfahrt for correction of the manuscript and editing of the
English language.
Author details
analyze & realize GmbH, Waldseeweg 6, 13467 Berlin, Germany.
GmbH, Hafenstraße 24, 49565 Bramsche, Germany.
Received: 11 November 2013 Accepted: 15 April 2014
Published: 28 April 2014
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Cite this article as: Stier et al.:Immune-modulatory effects of dietary
Yeast Beta-1,3/1,6-D-glucan. Nutrition Journal 2014 13:38.
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Stier et al. Nutrition Journal 2014, 13:38 Page 9 of 9
... The immunomodulatory properties of β-glucans are well-known (Goodridge et al. 2009). β-Glucan is a pathogen-associated molecular pattern (PAMP) molecule whose presence in the body often triggers the host's immune response in fungal and bacterial infections (Stier et al. 2014). The biological activity of β-glucans depends on the specific interaction with several pattern recognition receptors (PRR), such as Dectin-1, CR3, SR, and LacCer. ...
Polysaccharides, the most diverse forms of organic molecules in nature, exhibit a large number of different biological activities, such as immunomodulatory, radioprotective, antioxidant, regenerative, metabolic, signaling, antitumor, and anticoagulant. The reaction of cells to a polysaccharide is determined by its specific interaction with receptors present on the cell surface, the type of cells, and their condition. The effect of many polysaccharides depends non-linearly on their concentration. The same polysaccharide in different conditions can have very different effects on cells and organisms, up to the opposite; therefore, when conducting studies of the biological activity of polysaccharides, both for the purpose of developing new drugs or approaches to the treatment of patients, and in order to clarify the features of intracellular processes, information about already known research results is needed. There is a lot of scattered data on the biological activities of polysaccharides, but there are few reviews that would consider natural polysaccharides from various sources and possible molecular mechanisms of their action. The purpose of this review is to present the main results published at different times in order to facilitate the search for information necessary for conducting relevant studies.
... Thus, the research on β-glucan began and is still progressing today with numerous commercially available β-glucans available., such as Yestimun, which is an insoluble 1-3, 1-6 β-glucan derived from spent brewer's yeast. This yeast is a natural byproduct of the beer fermentation process (Stier et al., 2014). ...
β-glucans are a large class of complex polysaccharides found in abundant sources. Our dietary sources of β-glucans are cereals that include oats and barley, and non-cereal sources can consist of mushrooms, microalgae, bacteria, and seaweeds. There is substantial clinical interest in β-glucans; as they can be used for a variety of diseases including cancer and cardiovascular conditions. Suitable sources of β-glucans for biopharmaceutical applications include bacteria, microalgae, mycelium, and yeast. Environmental factors including culture medium can influence the biomass and ultimately β-glucan content. Therefore, cultivation conditions for the above organisms can be controlled for sustainable enhanced production of β-glucans. This review discusses the various sources of β-glucans and their cultivation conditions that may be optimised to exploit sustainable production. Finally, this article discusses the immune-modulatory potential of β-glucans from these sources.
... The degree of branching (DB), another parameter for evaluating polysaccharide structures, refers to the ratio of the number of glucose residues on the branches to the linear backbone. BGs with a DB in the range of 0.20-0.33 have higher biological activity (Stier, Ebbeskotte, and Gruenwald 2014). Magee et al. (2015) showed that after the DB of yeast BG decreased from 0.3 to <0.2, and the original triple helical structure was transformed into an aggregated structure. ...
Beta-glucan (BG), a polysaccharide comprised of interfacing glucose monomers joined via beta-glycosidic linkages, can be defined as a type of dietary fiber with high specificity based on its interaction with the gut microbiota. It can induce similar interindividual microbiota responses, thereby having beneficial effects on the human body. In this paper, we review the four main sources of BG (cereals, fungi, algae, and bacteria) and their differences in structure and content. The interaction of BG with gut microbiota and the resulting health effects have been highlighted, including immune enhancement, regulation of serum cholesterol and insulin levels, alleviation of obesity and improvement of cognitive disorders. Finally, the application of BG in food products and its beneficial effects on the gut microbiota of consumers were discussed. Although some of the mechanisms of action remain unclear, revealing the beneficial functions of BG from the perspective of gut microbiota can help provide theoretical support for the development of diets that target the regulation of microbiota.
... In the present study, fish fed with this prebiotic increased the expression levels of genes encoding the complement C3 and complement factor B and H compared to fish fed with inulin-and chitosancontaining diets. The up-regulation of genes encoding the complement C3 and C9 has been observed previously in the liver of the yellowtail Seriola lalandi supplemented with the commercial prebiotic GroBiotic-A (Juárez et al. 2021), which contains dry yeast and yeast extract, important sources of β-glucans (Stier et al. 2014). The complement C system consists of plasma proteins that can be activated directly by pathogens or indirectly by pathogen-bound antibodies, leading to a series of reaction cascades at the pathogen's surface and generating active components with various effector functions (Janeway et al. 2001). ...
Full-text available
In this study, we evaluated the effects of three prebiotics (inulin, β-glucan, and chitosan) on the physiological performance of Totoaba macdonaldi juveniles under culture conditions. The respiratory burst and the leucocyte content were measured in the blood to assess innate immune responses. The intestinal digestive capacity was evaluated by analyzing trypsin, amylase, and lipase activities, whereas the effects of such prebiotics at the transcriptomic level were assessed by implementing the RNA-Seq of liver tissue. After 60 days, fish fed with 0.5% chitosan diets showed the highest respiratory burst, the lowest lipase activity, and the highest number of differentially expressed genes (DEGs), where biological processes related to proteolysis, digestion, and lipid hydroxylation were the most affected. In addition, fish from the chitosan diet showed the highest expression of immunoglobulin genes. In contrast, fish fed with the 1% inulin diet presented the highest diet digestibility and trypsin and lipase activities. These physiological effects align with the highest expression of trypsin-like and chymotrypsin-like genes in the liver of fish from this diet. On the other hand, fish fed the 0.1% β-glucan diets showed the lowest amount of DEGs compared to the control group, most of which were associated with immune response, with an up-regulation of genes related to the complement system and a downregulation of immunoglobulin genes. Based on our results, we propose the inclusion of 1% dietary inulin to improve the digestibility of experimental diets and the addition of 0.5% chitosan to stimulate the immune system of T. macdonaldi juveniles.
... β-1,3/1,6-D-glucans derived from Spent Brewers' Yeast (Saccharomyces cerevisiae). Yeast cell walls typically contain approximately 30% of β-glucans of dry weight [27]. ...
Dietary β-glucans may be a useful tool to prime the host immune system and increase resistance against invading pathogens as the β-glucans influence the immune response. This prompted us to investigate the effects of dietary yeast β-1,3/1,6-D-glucans supplemented for a 14-day feeding period on liver and cardiac function and the oxidative mechanisms underlying these effects. We assessed relevant lipid peroxidation in the hepatic and cardiac tissue of rainbow trout (Oncorhynchus mykiss), European whitefish (Coregonus lavaretus), and graylings (Thymallus thymallus) after a 14-day period of supplementation with β-glucans. Thirty healthy grayling weighing 34.9 ± 1.9 g, thirty healthy rainbow trout weighing 55.9 ± 2.1 g, and thirty healthy European whitefish weighing 43.3 ± 2.7 g were used in the experiments. The fish were fed with a commercial basal diet at a rate of 1.5% body weight four times a day. After acclimation, the fish were randomly divided into six groups. The groups were fed for 14 days as follows: the control groups comprising grayling (n = 15), rainbow trout (n = 15), and European whitefish (n = 15) received a control basal diet and the β-glucan groups were fed with the Yestimun® food product at a dose of 1% of the basal feed (with 85% of β-1.3/1.6-glucans, Leiber GmbH, Bramsche, Germany). The basal feed was supplemented with 1% of Yestimun® powder (dose: 1 kg per 99 kg, w/w). This insoluble and highly purified preparation contains natural polysaccharides, e.g. β-1,3/1,6-D-glucans derived from Spent Brewers’ Yeast (Saccharomyces cerevisiae). Yeast cell walls typically contain approximately 30% of β-glucans of dry weight. Our results showed that feeding with low doses of β-glucans induced a decrease in TBARS levels in the hepatic and cardiac tissues of rainbow trout, andEuropean whitefish. Similarly, 14 days of feeding graylings with low doses of β-glucans resulted in a decrease in the TBARS levels both in the hepatic and cardiac tissues. This study confirms that dietary β-glucan is beneficial for promoting growth and enhancing antioxidant capacity against oxidative stress in rainbow trout, European whitefish, and graylings. Indeed, we cautiously hypothesized that feeding low β-glucans doses may help to boost antioxidant function, especially by the decrease of biomarkers of lipid peroxidation in the hepatic and cardiac tissues of these fish. Keywords: β-glucans, oxidative stress, lipid peroxidation, Thymallus thymallus, Oncorhynchus mykiss, Coregonus lavaretus
... β-Glucans from Saccharomyces cerevisiae are composed of β-(1 → 3)-and β-(1 → 6)-linked glucose residues [20], and represent 50-60% of the cell wall composition [21]. β-Glucans are known to improve the immune system [22,23], exhibit anti-inflammatory activity, and have prebiotic and antitumorigenic effects [19,24,25]. ...
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Brewer’s spent yeast (BSY) is a prevalent by-product of the brewing industry currently used in animal feed as a cheap source of protein. In this study, chemical composition of BSY from two different beer production (American IPA, BSY1, and Imperial Stout, BSY2) was characterized, aiming for potential use as nutraceutical sources. Cytotoxicity of BSY extracts was also tested in freshly isolated peripheral blood mononuclear cells (PBMCs) and in tumoral (pancreatic cancer tumor cells, PANC-1, and colorectal adenocarcinoma tumor cells, CACO-2) and non-tumoral (umbilical vein endothelial cells, HUVEC) cell lineages. BSY samples showed similar lipid and ash content, but slight differences in the content of reducing sugars, total proteins, moisture and total proteins. BSY2 sample presented higher glucans and phenolic compound concentrations than BSY1. Main phenolic compounds identified were xanthohumol, ferulic acid, p-coumaric acid (BSY1 and BSY2), and gallic acid (BSY2). BSY1 and BSY2 extracts showed similar antioxidant capacity. Neither BSY1 nor BSY2 were cytotoxic to PBMCs, HUVEC and CACO-2, but were cytotoxic to PANC-1 cells, in a concentration-dependent manner. Our findings revealed that the residue of brewery can be a value-added functional food product with an adjuvant role against PANC-1 cell lines. Graphical abstract
... As demonstrated by DPPH scavenging capacity of Saccharomyces cerevisiae GILA in vitro (Fig. 3), in vivo results also prove this ability to relieve oxidative stress (Fig. 7a). The S. cerevisiae strain was resistant to ETEC infection 17 , and S. cerevisiae cell wall glucan had an immune-modulatory effect, which could affect colitis reduction 13 . Spleen weight could be due to alleviating intestinal immune response 43 . ...
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Recently, several probiotic products have been developed; however, most probiotic applications focused on prokaryotic bacteria whereas eukaryotic probiotics have received little attention. Saccharomyces cerevisiae yeast strains are eukaryotes notable for their fermentation and functional food applications. The present study investigated the novel yeast strains isolated from Korean fermented beverages and examined their potential probiotic characteristics. We investigated seven strains among 100 isolates with probiotic characteristics further. The strains have capabilities such as auto-aggregation tendency, co-aggregation with a pathogen, hydrophobicity with n-hexadecane,1,1-diphenyl-2-picrylhydrazyl scavenging effect, survival in simulated gastrointestinal tract conditions and the adhesion ability of the strains to the Caco-2 cells. Furthermore, all the strains contained high cell wall glucan content, a polysaccharide with immunological effects. Internal transcribed spacer sequencing identified the Saccharomyces strains selected in the present study as probiotics. To examine the effects of alleviating inflammation in cells, nitric oxide generation in raw 264.7 cells with S. cerevisiae showed that S. cerevisiae GILA could be a potential probiotic strain able to alleviate inflammation. Three probiotics of S. cerevisiae GILA strains were chosen by in vivo screening with a dextran sulfate sodium-induced colitis murine model. In particular, GILA 118 down-regulates neutrophil–lymphocyte ratio and myeloperoxidase in mice treated with DSS. The expression levels of genes encoding tight junction proteins in the colon were upregulated, cytokine interleukin-10 was significantly increased, and tumor necrosis factor-α was reduced in the serum.
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Beta-glucans have immense potential to stimulate immune modulation in fish by being injected intramuscularly, supplemented with feed or immersion routes of administration. We studied how supplementing Labeo rohita’s diet with reishi mushroom powder containing beta-glucan influenced immunological function. A supplemented diet containing 10% reishi mushroom powder was administered for 120 days. Afterwards, analyses were conducted on different immunological parameters such as antioxidants, respiratory burst, reactive oxygen species (ROS), alternative complement activity, and serum immunoglobulin, which resulted significant increases (p < 0.05; p < 0.01) for the reishi mushroom-fed immune primed L. rohita. Additionally, analyzing various hematological parameters such as erythrocytes and leukocytes count were assessed to elucidate the immunomodulatory effects, indicating positive effects of dietary reishi mushroom powder on overall fish health. Furthermore, the bacterial challenge-test with 1.92 × 10⁴ CFU/ml intramuscular dose of Aeromonas veronii showed enhanced disease-defending system as total serum protein and lysozyme activity levels accelerated significantly (p < 0.01). Nevertheless, reishi mushroom powder contained with beta-glucan ameliorated the stress indicating parameters like acetylcholinesterase (AChE), serum-glutamic pyruvic transaminase (SGPT) and serum-glutamic oxaloacetic transaminase (SGOT) enzyme activities results suggested the fish’s physiology was unaffected. Therefore, the results indicated that adding dietary reishi mushroom as a source of beta-glucan could significantly boost the immune responses in Rohu.
Oat β-glucan (OG) has been shown to improve intestinal microecology in gestational diabetes mellitus (GDM), but the effect on fetal intestine health is unknown. Herein, we aimed to investigate the effects of OG supplementation during gestation in GDM dams on fetal intestinal immune development. OG was supplemented one week before mating until the end of the experiment. GDM rats were made with a high-fat diet (HFD) with a minimal streptozotocin (STZ) dose. The fetal intestines were sampled at gestation day (GD) 19.5, and the intestinal morphology, chemical barrier molecules, intraepithelial immune cell makers, and levels of inflammatory cytokines were investigated. The results showed that OG supplementation alleviated the decrease of the depth of fetal intestinal villi and crypts, the number of goblet cells (GCs), protein expression of mucin-1 (Muc1) and Muc2, the mRNA levels of Gpr41, Gpr43, and T cell markers, and increased the number of paneth cells (PCs), the mRNA levels of defensin-6 (defa6), and macrophage (Mø) marker and the expression of cytokines induced by GDM. In addition, OG supplementation alleviated the function of immune cell self-proliferation, chemotaxis and assembly capabilities, protein, fat, folic acid, and zinc absorption damaged by GDM. As indicated by these findings, OG supplementation before and during pregnancy improved the fetal intestinal chemical barriers, immune cells, cytokines, and the metabolism of nutrients to protect the fetal intestinal immunity.
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This study aimed to elucidate the relationship between the immunomodulatory effects of β-glucan and the composition of gut microbiota in mice. The mice were fed a diet containing β-glucan for 3 weeks, and feces, blood, and tissues were then collected to analyze the immunomodulatory effect and gut microbiota composition. Based on the results of the analysis of the expression level of immune-associated proteins, the high immunomodulatory effect group (HIE) and low immunomodulatory effect group (LIE) were categorized. Before the β-glucan diet, the proportions of the phylum Bacteroidota, family Muribaculaceae, and family Lactobacillaceae were significantly higher in HIE than in LIE. Furthermore, the genus Akkermansia was absent before the β-glucan diet and increased after β-glucan diet. These microbes had the ability to metabolize β-glucan or were beneficial to health. In conclusion, our findings demonstrate that variation in the composition of gut microbiota among individuals can result in varying expressions of β-glucan functionality. This outcome supports the notion that β-glucan may be metabolized through diverse pathways by gut microbes originally possessed by mice, subsequently producing various metabolites, such as short-chain fatty acids. Alternatively, the viscosity of the intestinal mucosa could be enhanced by β-glucan, potentially promoting the growth of certain bacteria (e.g., the genus Akkermansia). This study provides insights into the intricate interplay between β-glucan, gut microbiota, and immunomodulation.
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It is not known whether psychological stress suppresses host resistance to infection. To investigate this issue, we prospectively studied the relation between psychological stress and the frequency of documented clinical colds among subjects intentionally exposed to respiratory viruses. After completing questionnaires assessing degrees of psychological stress, 394 healthy subjects were given nasal drops containing one of five respiratory viruses (rhinovirus type 2, 9, or 14, respiratory syncytial virus, or coronavirus type 229E), and an additional 26 were given saline nasal drops. The subjects were then quarantined and monitored for the development of evidence of infection and symptoms. Clinical colds were defined as clinical symptoms in the presence of an infection verified by the isolation of virus or by an increase in the virus-specific antibody titer. The rates of both respiratory infection (P less than 0.005) and clinical colds (P less than 0.02) increased in a dose-response manner with increases in the degree of psychological stress. Infection rates ranged from approximately 74 percent to approximately 90 percent, according to levels of psychological stress, and the incidence of clinical colds ranged from approximately 27 percent to 47 percent. These effects were not altered when we controlled for age, sex, education, allergic status, weight, the season, the number of subjects housed together, the infectious status of subjects sharing the same housing, and virus-specific antibody status at base line (before challenge). Moreover, the associations observed were similar for all five challenge viruses. Several potential stress-illness mediators, including smoking, alcohol consumption, exercise, diet, quality of sleep, white-cell counts, and total immunoglobulin levels, did not explain the association between stress and illness. Similarly, controls for personality variables (self-esteem, personal control, and introversion-extraversion) failed to alter our findings. Psychological stress was associated in a dose-response manner with an increased risk of acute infectious respiratory illness, and this risk was attributable to increased rates of infection rather than to an increased frequency of symptoms after infection.
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The experimental material comprised 20 adult Wistar rats aged 12 weeks, divided into two equal groups (control and experimental) including five males and five females each. From the first day of the experiment, the experimental group was fed Murigran feed supplemented with β-1,3/1,6-D-glucan (Biolex Beta-HP) at a dosage of 12-19 mg/rat/d, depending on body weight, while the control animals were administered the same feed without any additives. On days 1 and 14 of the experiment, arterial blood samples were collected and diluted with heparin, and then the following parameters were determined: total protein and γ-globulin contents, lysozyme and ceruloplasmin activities, the proliferative response of blood lymphocytes after stimulation with LPS or ConA, metabolic activity, and the potential killing activity of phagocytes. The results showed that Biolex-Beta HP modulated the selected parameters of specific and non-specific humoral and cellular immunity in rats.
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The experiment was performed on 20 adult Wistar rats aged 12 weeks, divided into two equal groups (control and experimental), each comprised of five males and five females. From the first day of the experiment, the experimental group rats were fed Murigran feed supplemented with β-1,3/1,6-D-glucan at a dosage of 12-19 mg/rat/d, subject to body weight, while the controlgroup was administered the same feed without any additives. At the beginning of the experiment and then after 14 days, arterial blood samples were collected from the rats and diluted with heparin to measure and compare the phagocytic activity and oxidative metabolism of peripheral blood granulocytes and monocytes by flow cytometry. Statistically higher levels of the activity were observed in the group of rats administered glucan than in controls, expressed in terms of the percentage of phagocytic cells as well as average fluorescence intensity. β-1,3/1,6-D-glucan also had a positive effect on the oxidative metabolism of both granulocytes and monocytes after stimulation with E. coli, and on the oxidative metabolism of granulocytes after stimulation with PMA.
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Purpose: In a placebo-controlled, double-blind, randomized clinical trial, the effect of an insoluble yeast beta-glucan preparation on the incidences of common colds and its effect on common cold symptoms were compared to placebo. Methods: 100 healthy participants with recurring infections were randomly assigned to receive either placebo or yeast beta-glucan (Yestimun ® ; n = 50 each group) over a period of 26 weeks. The subjects had to document each common cold episode in a diary, and rate 6 predefined infections symptoms on a 3-point rating scale during an infection period, resulting in an infection score. The common cold episodes were confirmed by the investigators. Results: A total of 171 common cold episodes were documented. Of these, 76 were experienced by 38 subjects in the beta-glucan group and 96 were experienced by 48 subjects in the placebo group (p = 0.406). The beta-glucan group had significantly more sub-jects without incidences of common cold than the placebo group (15.6% vs 2.0%; p = 0.019). During the most intense infection season (first 13 weeks of the study), the beta-glucan group had significantly less infections compared to pla-cebo (p = 0.02). Beta-glucan significantly reduced the typical cold symptoms ("sore throat and/or difficulty swallow-ing", "hoarseness and/or cough" and "runny nose") as opposed to placebo. Conclusion: The present study demonstrates a prophylactic effect of yeast beta-glucan on the occurrence of common colds as opposed to placebo. In addition, when these episodes occurred, they were from the beginning less pronounced and subsided faster.
Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a scientific opinion on the safety of ‘yeast beta-glucans’ as a novel food ingredient in the context of Regulation (EC) No. 258/97 taking account of the comments/objections of a scientific nature raised by the Member States. ‘Yeast beta-glucans’ consists of complex, high molecular mass polysaccharides derived from the cell wall of baker's yeast Saccharomyces cerevisiae. This novel food application concerns both insoluble as well as soluble ‘yeast beta-glucans’. The source, characterisation, specification and production process do not give reasons for concern. The applicant intends to market ‘yeast beta-glucans’ in food supplements at dose levels of up to 375 mg per day and in foods for particular nutritional uses (PARNUTS) at dose levels of up to 600 mg per day. It is not intended for infant formulae and follow-on formulae. In addition, the applicant intends to market ‘yeast beta-glucans’ in a variety of foods including beverages for the general population. The Panel notes that the “high intake” scenario for ‘yeast beta-glucans’ is grossly similar to the background intake of beta-glucans from other dietary sources. Data provided on (sub)acute and sub-chronic toxicity, absorption, and limited human data do not give reason for concern. The Panel considers that the allergenic risk of the ‘yeast beta-glucans’ is not higher than the risk from other products containing baker's yeast. Beta-glucans from other sources have already been evaluated for safety by EFSA. On the basis of the nature of ‘yeast beta-glucans’, the significant history of use of its source, the provided intake estimate and the supplementary data from human and animal studies, Panel concludes that ‘yeast beta-glucans’ is safe at the proposed conditions of use.
A randomized, placebo-controlled, double blind design study was conducted to evaluate the effect of beta-1,3/1,6 glucan derived from bakers yeast, a commercially available dietary supplement, on symptoms associated with upper-respiratory tract infections and psychological well-being. Moderate to highly stressed subjects (45 men, 105 women) ranging in age from 18-65 (mean age: 39 +/- 11 years) were administered placebo, 250 mg, or 500 mg beta-1,3/1,6 glucan during a 4 week treatment period. Subjects in both treatment groups (250 mg and 500 mg beta-1,3/1,6 glucan per day) reported fewer upper respiratory tract infection symptoms, better overall health and increased vigour, and decreased tension, fatigue, and confusion based on the profile of mood states assessment.
Objective: To examine the safety and efficacy of multiple doses of PGG-glucan (poly- [ 1-6]-B-Dglucopyranosyl-[ 1-3]-B-D-glucopyranose) in high-risk patients undergoing major thoracic or abdominal surgery. Design: An interventional, multicenter, double-blind, randomized, placebo-controlled study. Setting: Four university-affiliated medical centers. Patients: Sixty-seven high-risk patients undergoing major thoracic or abdominal surgery. Intervention: Patients were randomized in a 1:1:1:1 ratio to receive saline placebo or PGG-glucan at a dose of 0.1 mg/kg, 0.5 mg/kg, and 1.0 mg/kg or 2.0 mg/kg. One dose was administered before surgery and three doses were administered after surgery. Main Outcome Measures: To examine the safety and efficacy of PGG-glucan infusion and to identify potentially important factors for a planned phase III study. Results: A dose-response trend with regard to infection incidence among patients who received PGG-glucan was observed. Serious infections occurred in four patients who received placebo and in three patients who received PGG-glucan at a dose of 0.1 mg/kg. However, only one patient who received PGG-glucan at a high dose had a serious infection. The incidence and severity of adverse events was comparable in all groups. Conclusions: PGG-glucan was generally safe and well tolerated, may decrease postoperative infection rates, and warrants further investigation in a planned phase III trial.(Arch Surg. 1994;129:1204-1210)