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Prebiotics, immune function, infection and inflammation: A review of the evidence

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β2-1 Fructans are carbohydrate molecules with prebiotic properties. Through resistance to digestion in the upper gastrointestinal tract, they reach the colon intact, where they selectively stimulate the growth and/or activity of beneficial members of the gut microbiota. Through this modification of the intestinal microbiota, and by additional mechanisms, β2-1 fructans may have beneficial effects upon immune function, ability to combat infection, and inflammatory processes and conditions. In this paper, we have collated, summarised and evaluated studies investigating these areas. Twenty-one studies in laboratory animals suggest that some aspects of innate and adaptive immunity of the gut and the systemic immune systems are modified by β2-1 fructans. In man, two studies in children and nine studies in adults indicate that the adaptive immune system may be modified by β2-1 fructans. Thirteen studies in animal models of intestinal infections conclude a beneficial effect of β2-1 fructans. Ten trials involving infants and children have mostly reported benefits on infectious outcomes; in fifteen adult trials, little effect was generally seen, although in specific situations, certain β2-1 fructans may be beneficial. Ten studies in animal models show benefit of β2-1 fructans with regard to intestinal inflammation. Human studies report some benefits regarding inflammatory bowel disease (four positive studies) and atopic dermatitis (one positive study), but findings in irritable bowel syndrome are inconsistent. Therefore, overall the results indicate that β2-1 fructans are able to modulate some aspects of immune function, to improve the host's ability to respond successfully to certain intestinal infections, and to modify some inflammatory conditions.
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Review Article
Prebiotics, immune function, infection and inflammation:
a review of the evidence
Amy R. Lomax* and Philip C. Calder
Institute of Human Nutrition, School of Medicine, University of Southampton, Tremona Road, Southampton, SO16 6YD, UK
(Received 26 February 2008 – Revised 14 May 2008 – Accepted 27 May 2008 – First published online 25 September 2008)
b2-1 Fructans are carbohydrate molecules with prebiotic properties. Through resistance to digestion in the upper gastrointestinal tract, they reach the
colon intact, where they selectively stimulate the growth and/or activity of beneficial members of the gut microbiota. Through this modification of the
intestinal microbiota, and by additional mechanisms, b2-1 fructans may have beneficial effects upon immune function, ability to combat infection,
and inflammatory processes and conditions. In this paper, we have collated, summarised and evaluated studies investigating these areas. Twenty-one
studies in laboratory animals suggest that some aspects of innate and adaptive immunity of the gut and the systemic immune systems are modified by
b2-1 fructans. In man, two studies in children and nine studies in adults indicate that the adaptive immune system may be modified by b2-1 fructans.
Thirteen studies in animal models of intestinal infections conclude a beneficial effect of b2-1 fructans. Ten trials involving infants and children have
mostly reported benefits on infectious outcomes; in fifteen adult trials, little effect was generally seen, although in specific situations, certain b2-1
fructans may be beneficial. Ten studies in animal models show benefit of b2-1 fructans with regard to intestinal inflammation. Human studies report
some benefits regarding inflammatory bowel disease (four positive studies) and atopic dermatitis (one positive study), but findings in irritable bowel
syndrome are inconsistent. Therefore, overall the results indicate that b2-1 fructans are able to modulate some aspects of immune function, to
improve the host’s ability to respond successfully to certain intestinal infections, and to modify some inflammatory conditions.
b2-1 Fructans: Inulin: Oligofructose: Fructo-oligosaccharides: Cytokines
Prebiotics have been defined as ‘non-digestible food ingredients
that beneficially affect the host by selectively stimulating the
growth, and/or activity, of one or a limited number of beneficial
bacteria in the colon and thus improve host health’
(1)
. Research
on the potential health benefits of prebiotics has occurred over
the last 15 years or so, with a recent interest in the effects on
the immune system, the host’s ability to fight infection, and
inflammatory processes and conditions. These effects have
been reviewed several times
(2 – 7)
but to our knowledge there
are no reviews that bring together all of the available studies
in all of the these areas. Thus, the aim of the present article is
to describe the structure and dietary sources of prebiotics, and
to summarise and evaluate studies investigating the influence
of prebiotics on immunity, host defence, and inflammatory pro-
cesses and conditions.
Structure of prebiotics
b2-1 Fructans, which include inulin (IN) and fructo-oligosac-
charides (FOS), fulfil the criteria for prebiotics
(8)
. Other
carbohydrates including galacto-oligosaccharides (GOS),
gluco-oligosaccharides, isomalto-oligosaccharides, lactulose,
mannanoligosaccharides (MOS), nigero-oligosaccharides, oat
b-glucans, raffinose, soyabean oligosaccharides, transgalacto-
oligosaccharides and xylo-oligosaccharides are considered as
candidate prebiotics. Only studies with b2-1 fructans will be
considered in the present review, as these are the most widely
studied with regard to potential modulation of the immune
system, and relatively little information is available on the
immunomodulatory properties of the other candidate prebiotics.
IN is a linear carbohydrate molecule which contains
b-(2 !1) fructosylfructose linkages with a terminal glu-
cose
(9)
. IN may contain between two and sixty fructose resi-
dues (Fig. 1), with an average of twelve. Partial enzymatic
hydrolysis of IN yields a FOS known as oligofructose
(OF), which can have a terminal glucose or fructose residue
(Fig. 1). In OF there can be two to eight (average five) fruc-
tose residues with a terminal glucose residue or a chain of
three to eight (average five) fructose residues
(10)
. Thus IN
and OF differ according to degree of polymerisation
(Fig. 1). Short-chain FOS may also be derived by enzymatic
addition of fructose residues to sucrose (Fig. 1); the products
formed contain two to four fructose residues with a terminal
glucose residue (Fig. 1). Some studies have used products
*Corresponding author: Miss Amy R. Lomax, fax þ44 2380 795255, email arl203@soton.ac.uk
Abbreviations: FOS, fructo-oligosaccharides; GALT, gut-associated lymphoid tissue; GOS, galacto-oligosaccharides; IFN, interferon; IN, inulin; MHC, major
histocompatability complex; MLN, mesenteric lymph nodes; MOS, mannanoligosaccharides; NK, natural killer; OF, oligofructose; PP, Peyer’s patches.
British Journal of Nutrition (2009), 101, 633–658 doi:10.1017/S0007114508055608
qThe Authors 2008
British Journal of Nutrition
containing OF-enriched IN or IN with shorter-chain FOS
removed, while some studies do not specify exactly what
they used, merely referring to FOS.
Dietary sources of prebiotics
IN is found naturally in a variety of plant foods such as
bananas, barley, chicory, garlic, Jerusalem artichoke, leeks,
onions and wheat
(11)
. IN has been extracted from chicory
roots, Jerusalem artichoke, artichoke, dahlias and dande-
lions
(12)
. Typical daily intakes of IN for adults are estimated
to be between 3 and 11 g/d in Europe, and between 1 and
4 g/d in North America
(11)
.
Oligosaccharides, including some believed to be prebiotics,
are present in human breast milk
(13)
. They can be found in con-
centrations of up to 12 g/l, making them the third largest com-
ponent of breast milk
(14)
. The presence of oligosaccharides in
large amounts in breast milk suggests that these compounds
may play an important role in early infant development, perhaps
of the gut, its microbiotia and the immune system. Breast milk
contains many compounds and substances that influence gut
and immune maturation and consequently has a protective role
against infections
(15)
and possibly allergy development
(16)
.
Oligosaccharides may contribute to these protective actions. It
is possible that the oligosaccharides are present in breast milk
in the mix and concentrations required for optimum protection,
and for the development of the immune system.
Overview of the mechanism of action of prebiotics
b2-1 Fructans fulfil the three criteria which must be met in order
to be classified a prebiotic, as defined by Gibson & Roberfroid
(1)
:
(1) Resistance to hydrolysis or absorption in the upper
gastrointestinal tract (as the b-(2 !1) osidic bond is not
hydrolysed by mammalian digestive enzymes). This was
shown in early in vitro tests, where b2-1 fructans were incu-
bated with rat pancreatic and small intestinal homogenates,
and shown to be poorly digested
(17)
. Fulfilment of this
criterion has also been demonstrated in man through the
study of ileostomy subjects, where 87 % of dietary IN
was recovered in the ileum
(18)
, thus establishing the survi-
val of IN through the upper gastrointestinal tract. The
non-digestibility of b2-1 fructans in the small intestine
has also been demonstrated in healthy volunteers
(19)
.
(2) Fermented by the intestinal microbiota. This has been
demonstrated in experiments in which b2-1 fructans
were completely metabolised in microbial fermentation
cultures
(11,20)
.
(3) Selectively stimulate the growth and/or activity of
beneficial intestinal bacteria, such as Lactobacillius
species and Bifidobacterium species. Studies in laboratory
animals and man show that prebiotics do increase the
numbers of these types of bacteria in the intestinal
tract
(21 – 26)
. Other experiments establish that b2-1 fruc-
tans are selectively fermented by most Bifidobacterium
species
(27)
, and also by some Lactobacillius species
(28)
,
as these bacteria produce the intracellular fructosyl-
fructofuranosidase that is needed for hydrolysis of the
b-(2 !1) osidic bond in b2-1 fructans
(10)
.
As a result of intestinal fermentation and promotion of growth of
beneficial members of the gut microbiota, prebiotics may influ-
ence host defence (Fig. 2). Firstly, by increasing the number of
bifidobacteria, there will be increased competition with patho-
genic bacteria for binding sites on the intestinal epithelium
and for nutrients, thus inhibiting survival of the pathogenic
strains. Beneficial members of the gut microbiota bacteria may
also cross the intestinal barrier into the Peyer’s patches (PP),
and activate immune cells there
(29)
. Others suggest that it is
not the beneficial bacteria themselves that cross the barrier,
but microbial substances such as cell wall components and
cytoplasmic antigens
(30)
.Bifidobacterium species and Lactoba-
cillius species are able to produce antibacterial substances that
can inhibit the growth and survival of pathogens
(31)
.
Secondly, the fermentation of prebiotics by the Bifido-
bacterium species produces SCFA
(1)
, which have the follow-
ing effects:
.Acidification of the colonic environment, which is detri-
mental to some pathogenic strains of bacteria
(32)
such as
some pathogenic species of bacteroides, clostridia and
coliforms
(31)
.
.Acidification of the colon favouring mucin production
(33)
.
This is believed to improve mucosal morphology, so
decreasing pathogenic bacterial colonisation and
translocation.
.Binding to SCFA receptors (G protein coupled receptors
41 and 43) on immune cells within the gut-associated
lymphoid tissues (GALT)
(34 – 36)
.
.Butyrate decreases the requirement of epithelial cells for
glutamine, thus sparing more for GALT
(37)
.
.Butyrate may also alter epithelial cell gene expression, for
example IL-8 and monocyte chemoattractant protein 1,
and this in turn would alter the signalling of the epithelial
cell to the mucosal immune system
(38)
.
Finally, prebiotics may also influence host immune function
through alternative mechanisms to the modulation of ben-
eficial bacteria in the gut. It is hypothesised that carbohydrate
moieties on the prebiotic may interact with receptors on
Inulin
Sucrose
Partial
hydrolysis
Enzymatic
addition
Oligofructose
Oligofructose
(also known as short-chain
fructo-oligosaccharides)
(enzymatic)
GFF
GFF
GFGF F
RF F F
DP = 2–60
DP = 2–7
DP = 2 7
DP = 2–4
β2–1
β2–1
β2–1
β2–1
Fig. 1. The structures of b2-1 fructans. DP, degree of polymerisation; F, fruc-
tose; G, glucose; RF, reducing fructose.
A. R. Lomax and P. C. Calder634
British Journal of Nutrition
immune cells. Although a specific fructose receptor has not
yet been identified, receptors for b-glucan
(39,40)
and man-
nose
(41)
have been identified on immune cells, and in vitro,
fructose has been shown to alter non-opsonic phagocytosis
(42)
,
suggesting that a receptor for fructose on immune cells may
exist. In addition, some oligosaccharides, for example OF,
can bind to receptors on pathogenic bacteria and prevent
them from attaching to this same sugar on the epithelial mem-
brane, thus preventing adherence
(43)
.
Prebiotics and immune function
This section reviews studies in experimental animals and in
man that investigate the effects of increased consumption of
b2-1 fructans on aspects of immune function.
Studies in laboratory animals
Studies conducted in laboratory animals are useful because
they can be highly controlled, thus eliminating sources of vari-
ation in diet and in immune response. Twenty-two studies of
b2-1 fructans reporting immune outcomes were identified in
mice, rats, pigs and dogs, and are summarised in Table 1.
Many of these studies show benefits of b2-1 fructans to
some aspects of immune function, while showing no effect
on other aspects. Thus, b2-1 fructans may have specific effects
upon different components of the immune system. Here, the
studies are separated into those which investigate the GALT
and those which investigate the systemic immune system.
The GALT is made up of the mucosa-associated lymphoid
tissues of the gut, and is located underneath a columnar
epithelial layer and mucus layer. Within the epithelial
layer, M (microfold) cells are distributed. These are antigen-
presenting cells and are capable of transporting antigen from
the gut lumen into the PP of the GALT. It is in the PP that
antigen-presenting cells process and present the antigen
to lymphocytes, which subsequently become activated.
These lymphocytes then travel via the lymph to the mesenteric
lymph nodes (MLN), through the thoracic duct and into the
blood, where they become re-localised to the lamina propria
of the intestine. Thus, the antigen-specific activated lympho-
cytes become distributed throughout the intestine.
Gut-associated lymphoid tissue.Innate immune system:
The effect of b2-1 fructans upon macrophage number and
function has been studied, with the results suggesting that
macrophage functions are enhanced by the addition of b2-1
fructans to the diet. In Clostridia difficile-challenged mice,
caecal macrophage and granulocyte numbers were increased
in response to antibiotic treatment when a short course of
FOS was given
(44)
. Peritoneal macrophage phagocytic activity
was also increased in rodents given IN or OF for varying
periods of time
(45,46)
and in mice vaccinated with Salmonella
typhimurium
(47)
and respiratory burst was also increased
(45)
.
Major histocompatability complex (MHC) II molecule
expression was also shown to increase on antigen-presenting
cells in the MLN of rats upon OF and IN supplementation
(45)
.
However, natural killer (NK) cell cytotoxicity in intra-epi-
thelial lymphocytes of adult dogs was not affected by sup-
plementation of FOS with other fermentable fibres
(48)
, and
NK cell activity in MLN or PP of rats was not affected by
OF-enriched IN
(49)
.
Thus, from the limited number of animal studies available,
it appears that the innate immune system of the gut may be
improved by b2-1 fructan intake, which could result in a
Dietary
β2– 1 fructans
Stomach
Small intestine
The fermentation of β2–1 fructans by the
beneficial bacteria has several beneficial effects
1· Increase in the numbers of beneficial bacteria 2· Fermentation produces SCFA 3· Benefical bacteria independent effects of
β2–1 fructans
Colon
When β2–1 fructans reach the colon they are fermented by the intestinal microflora·
This fermentation is selective, and β2–1 fructans stimulate the growth and / or
activity of benenficial bacteria in the colon, such as bifidobacteria and lactobacilli
The β-(2–1) osidic bond present in β2–1 fructans
is resistant to hydrolysis by mammalian digestive
enzymes, and so β2–1 fructans reach the colon
virtually intact
Fig. 2. Mechanisms by which b2-1 fructans may influence host defence.
Prebiotics and immunity 635
British Journal of Nutrition
Table 1. Effects of b2-1 fructans on immune function in laboratory animals
Reference no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
44 Fructo-oligosaccharides (3 %
w/v drinking water)
Mice (male, 12 weeks old); half were
treated with antibiotics, half were
not; all challenged with Clostridium
difficile
"Caecal macrophages and granulocytes in antibiotic-treated mice
Non-significant "in macrophage numbers in colon
Fructo-oligosaccharide treatment prevented the following effects seen with antibiotics:
Increased dendritic cells and gd T cells in lamina propria of the caecum
Decreased PGE
2
and LTB
4
in small intestine, colon and caecum
128 Short-chain fructo-oligosac-
charides (5·8 % w/w diet)
Mice (male and female, 6–7 weeks
old); C57BL/6J min/þmice (model
of familial adenomatous polyposis
and sporadic intestinal cancers,
lesions mainly affect the small
intestine)
Stimulation of the gut-associated lymphoid tissue and development of PP, as shown by an
increase in small intestinal lymphoid nodule count
48 Fermentable fibre, including
fructo-oligosaccharides,
beet pulp and gum arabic
(0·87 % w/w diet)
Dogs (adult) In peripheral blood:
"CD4
þ
/CD8
þ
ratio
#Proportion of B (Ig
þ
cells (IgG
þ
,IgA
þ
,IgM
þ
))
No change in NK cytotoxicity
No change in mitogen responses of peripheral blood mononuclear cells
In gut-associated lymphoid tissue:
"Proportion of CD4
þ
cells (expressing CD45R
þ
) and CD5
þ
cells (total T cells) in MLN cells
"Proportion of CD8
þ
cells in intra-epithelial, PP and lamina propria cells
#CD4
þ
/CD8
þ
ratio in lamina propria
"T cell mitogen responses in intra-epithelial lymphocytes (to phytohaemagglutinin) and MLN (to all
mitogens)
#T cell mitogen responses in PP (to concanavalin A and phytohaemagglutinin) and lamina
propria cells (to concanavalin A)
No change in NK cytotoxicity in intraepithelial lymphocytes
56 Fructo-oligosaccharides (1 %
w/w diet), with/without pro-
biotic mix of Lactobacillus
acidophilus,L. rhamnosus,
Enterococcus faecium,
Streptococcus thermophilus,
L. bulgaricus
Piglets (21 d old, Salmonella-free);
infected with S. typhimurium
Synbiotics "whole blood phagocyte activation level
No effect of fructo-oligosaccharides on:
Whole blood phagocyte activation level
Recovery of IgA in small intestine
129 Oligofructose (3 g/d) plus
Lactobacillus paracasei
L. paracasei was also given
alone
Piglets (newborn) 10 d after birth the following were observed:
Significant differences between the L. paracasei group and the synbiotic group regarding
counts of leucocytes, lymphocytes, neutrophils, CD2
þ
T cells, CD4
þ
T cells, B cells and
macrophages in blood
#% phagocytic activity of leucocytes and neutrophils in blood in the synbiotic group compared
to the control group
No effect of L. paracasei or the synbiotic upon total Ig concentrations in the sera
10 d after weaning the following were observed:
In the synbiotic group, counts of leucocytes, lymphocytes, neutrophils, CD2
þ
T cells,
CD4
þ
T cells, CD8
þ
T cells, B cells and macrophages in blood had increased compared to the
previous measurements
The synbiotic group had significantly greater CD4
þ
T cell and B cell counts in blood compared
to the L. paracasei group
"% phagocytic activity of leucocytes and neutrophils in blood in the synbiotic group, but not in the
L. paracasei group
No effect of L. paracasei or the synbiotic upon total Ig concentrations in the sera
A. R. Lomax and P. C. Calder636
British Journal of Nutrition
Table 1. Continued
Reference no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
53 Fructo-oligosaccharides
and/or mannanoligosacca-
harides (2 g/d)
Dogs (female, adult) "Ileal IgA concentration with fructo-oligosaccharides plus mannanoligosaccharides
No effect of fructo-oligosaccharides alone or in combination with mannanoligosaccharides on:
Total leucocyte, neutrophil or lymphocyte numbers
Serum IgA, IgG or IgM concentrations
Faecal IgA concentrations
54 Fructo-oligosaccharides
(4 g/d) and mannanoligosac-
charides (2 g/d)
Dogs (adult) #Blood neutrophils
"Blood lymphocytes
No effect upon serum, faecal or ileal Ig concentrations
88 Oligofructose (1·25 g/l drinking
water) in combination Bifi-
dobacterium bifidum and B.
infantis
Mice (pups); infected with Rhesus
rotavirus
Oligofructose did not have any additional benefit compared to when the probiotic was given
alone, but both treatments:
"Rotavirus-specific IgA levels in serum 28 d post-infection
#Duration of a strong rotavirus-specific IgA response in faeces
#IgA and IgG positive B cell percentages in the PP at 28 d post-infection
No effect of bifidobacteria or bifidobacteria plus oligofructose upon:
Serum rotavirus-specific IgG
Rhesus rotavirus antigen concentration in stools
51 Fructo-oligosaccharides (2·5
or 7·5 % w/w diet)
Mice (female, 6 weeks old) "Total faecal IgA with 2·5 % but not 7·5 % fructo-oligosaccharides
"Size of PP with 7·5 % fructooligosaccharides
"Total IgA secretion by PP cells with 2·5 and 7·5 % fructo-oligosaccharides
"IL-10 and IFN-gproduction (dose dependent) from PP CD4
þ
T cells stimulated with sonicated
components from B. pseudocatenulatum from Gram-positive bacteria, but not by lipopolysaccharide
or concanavalin A stimulation
High levels of IL-5 secretion from PP CD4
þ
T cells maintained with both doses fructo-oligosaccharides,
and IL-6 secretion was maintained with 7·5 % fructo-oligosaccharides
"IFN-gproduction from spleen CD4
þ
T cells (dose dependent)
#IL-5 and IL-6 production from spleen CD4
þ
T cells
#Serum IgG1 with both doses of fructo-oligosaccharides
No effect on serum IgG2a
46 Inulin with shorter-chain
fructo-oligosaccharides
removed (10 % w/w diet) or
oligofructose (either 2·5 or
10 % w/w diet)
Mice (female, 5–6 weeks old) #Leucocyte counts with 10 % inulin or 2·5 or 10 % oligofructose
"NK activity of splenocytes with 10 % inulin or oligofructose
"Peritoneal macrophage phagocytosis of Listeria monocytogenes with 10 % inulin or oligofructose
No effect on:
Lymphocyte subsets in spleen and thymus (% of CD4
þ
, CD8
þ
, CD4
þ
/CD8
þ
, T and B cells)
Faecal IgA concentrations
50 Fructo-oligosaccharides
(10 % w/w diet)
Mice (female, 6–8 weeks old);
healthy or endotoxaemic (induced
by lipopolysaccharide from
Escherichia coli)
"Total number of immune cells in PP in healthy and endotoxaemic mice
"B lymphocytes in PP in both healthy and endotoxaemic mice
"T lymphocytes and CD4
þ
/CD8
þ
ratio in PP in endotoxaemic mice only
58 Chicory (1 % w/w diet) and/or
mannanoligosaccharides
(1 % w/w diet)
Dogs (male and female, seniors,
8–11 years old)
Chicory in combination with mannanoligosaccharides decreased peripheral blood lymphocyte
concentration
Chicory alone and in combination with mannanoligosaccharides non-significantly increased neutrophil
concentrations in blood
No effect of chicory alone or in combination with mannanoligosaccharides on:
Total peripheral leucocyte concentration
Serum concentrations of IgA, IgG or IgM
Concentrations of monocytes or eosinophils in blood
Prebiotics and immunity 637
British Journal of Nutrition
Table 1. Continued
Reference no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
52 Fructo-oligosaccharides
(5 % w/w diet)
Mice (newborn) "Total intestinal IgA (ileum, jejunum and colon)
"Ileal and colonic polymeric Ig receptor expression at 36 d
"Ileal IgA secretion rate at 37 d
"IgA response of PP cells
"% of B220
þ
IgA
þ
cells (IgA committed cells, thus promoted isotype switching from IgM to IgA in PP
B cells)
No effect on % of B220
þ
cells or % of B220
þ
IgM
þ
cells in PP
49 Oligofructose-enriched inulin
(10 % w/w diet) Also stu-
died probiotics (L. rhamno-
sus GG and B. lactis Bb12)
and a synbiotic (combi-
nation of Synergy1
w
and
the probiotics)
Rats (male, 12–13 weeks old) #Oxidative burst activity in blood neutrophils in synbiotic group compared to probiotic group
"IL-10 and IFN-gproduction in PP in oligofructose-enriched inulin group
"Secretory IgA concentration in ileum in synbiotic group
"Secretory IgA concentration in caecum in oligofructose-enriched inulin group
No effect of oligofructose-enriched inulin on:
CD4
þ
and CD8
þ
T lymphocytes in spleen, MLN and blood
Neutrophil and monocytes phagocytosis of E. coli in blood and spleen
NK activity in spleen, MLN, PP (non-significant tendency to increase this in peripheral blood mono
nuclear cells)
Lymphocyte proliferation in spleen, MLN, PP
Cytokine production in spleen or MLN
57
130
Oligofructose-enriched inulin
(10 % w/w diet) Also stu-
died probiotics (L. rhamno-
sus GG and B. lactis Bb12)
and a synbiotic (combi-
nation of Synergy 1
w
and
the probiotics)
Inulin (4·8 % w/w diet)
Rats (male, 4-5 weeks old); model of
colon cancer
Rats (21 d old, male and female); dia-
betes resistant or diabetes prone
Oligofructose-enriched inulin:
"NK cell-like cytotoxic function in the spleen of rats without colon cancer
Prevented the #in NK cell-like cytotoxic function seen in controls, in rats with colon cancer
"IL-10 production in MLN of rats without colon cancer
"IL-10 production by PP in rats with colon cancer
#CD4
þ
/CD8
þ
ratio in spleen without significantly changing the % of CD4
þ
or CD8
þ
T-lymphocytes
in rats without colon cancer
No effect on IL-10 production by splenocytes in rats with or without colon cancer
In diabetes-resistant rats:
"Small intestine length
#Number of splenocytes
"CD8
þ
lymphocytes in PP
"Proliferation of splenocytes and MLN cells to mitogens
#Production of IL-4 and
"production of IL-10 by stimulated splenocytes
No effect on:
Spleen weight
Immune cell numbers in PP
IgA
þ
cells in jejunal lamina propria
Immune cell phenotypes in spleen and MLN
Splenocyte production of IL-2, IFN-gor TGF-b
MLN cell production of IFN-g, TNF-aor TGF-b
PP cell production of TGF-b
In diabetes-prone rats:
#Number of splenocytes
"IgA
þ
cells in jejunal lamina propria
"B lymphocytes in PP
#Production of IL-4 and
"production of IL-10 by stimulated splenocytes
A. R. Lomax and P. C. Calder638
British Journal of Nutrition
Table 1. Continued
Reference no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
No effect on:
Small intestine length
Spleen weight
Immune cell numbers in PP
Immune cell phenotypes in spleen and MLN
Proliferation of splenocytes and MLN cells in response to mitogens
Splenocyte production of IL-2, IFN-gor TGF-b
MLN cell production of IFN-g, TNF-aor TGF-b
PP cell production of TGF-b
45 Oligofructose or inulin (10 %
w/w diet)
Rats (male) Oligofructose and inulin:
"number of T cells in spleen, MLN and thymus
"MHCII on antigen-presenting cells in spleen, MLN and thymus
"IL-2 and IL-4 in blood
"peritoneal macrophage phagocytosis
"peritoneal macrophage superoxide production
No effect on:
Apoptosis of immunocytes
55 Inulin (3 % w/w diet) Dogs (adult, 2–11 years old); hypoal-
lergenic
No effect on:
Total serum IgA, IgE, IgG or IgM concentrations
Total faecal IgA concentration
23 Galacto-oligosaccharides and
inulin with the shorter-chain
fructoligosaccharides
removed (9:1 ratio) at differ-
ent doses (1– 10 % w/w diet)
Mice (female, 6–8 weeks old); vacci-
nated with influenza vaccine; DTH
to influenza vaccine
"DTH response in a dose-dependent manner (5 % w/w of diet was the optimal dose)
No effect on:
Vaccine-specific serum antibody (total IgG, IgG1 and IgG2a) concentration (humoral response)
Vaccine-induced splenocyte proliferation (T cell activation)
Other oligosaccharides were also tested (inulin/FOS; short-chain FOS; inulin) but these did not
significantly affect the DTH response
131 Oligofructose (0·91 % w/w diet) Dogs (pregnant female þpups to 49
d of age); pups vaccinated with
Bordetella bronchiseptica vaccine
at day 21
In pregnant females and pups no effect on:
Serum IgG1, IgG2, IgA or IgM
In colostrum and milk:
"IgM, but no effect on IgG1, IgG2 or IgA In pups no effect on:
Post-vaccination Ig nasal secretions
78 Short-chain oligofructose or
inulin (1 % w/w diet)
Puppies (12 weeks old, male and
female); infected with S. typhimur-
ium
Tendency for inulin to #serum IgG (due to epithelial damage)
Both short-chain oligofructose and inulin:
No change in serum IgA or IgM concentrations
47 Oligofructose and inulin with
the shorter-chain
fructo-oligosaccahrides
removed (70:30 ratio; 5 %
w/w diet)
Mice (female, 6 weeks old); immu-
nised with S. typhimurium vaccine
"Vaccine-specific faecal IgA and plasma IgG levels
"Peritoneal macrophage activity 1 week post-immunisation
"Mean fluorescence intensity of MHCII
þ
cells in spleen
"IL-12 and IFN-gproduction by splenocytes
"Survival from Salmonella infection when given vaccine
No effect on:
Total serum IgG or total faecal IgA
% of cell subsets (CD4
þ
, CD8
þ
, B220
þ
, MHCII
þ
, CD11b
þ
, CD11c
þ
) in spleen
Splenocyte proliferation rates
TNF-aproduction by splenocytes
Salmonella translocation to lymphoid organs (PP, MLN, liver and spleen)
DTH, delayed type hypersensitivity; IFN, interferon; LTB
4,
leukotriene B
4
; MHC, major histocompatability complex; MLN, mesenteric lymph nodes; NK, natural killer; PP, Peyer’s patches; TGF, transforming growth factor; ", increase/in-
creased; #, decrease/decreased.
Prebiotics and immunity 639
British Journal of Nutrition
beneficial effect on the host’s primary response to infection.
However, studies measuring NK cell activity did not find
any effect upon this component of the innate immune
system, which plays a major role in the anti-tumour immunity
and destruction of virus-infected cells. Future studies should
build upon those reported here, to create a more complete pic-
ture of how b2-1 fructans affect the innate immune system.
Adaptive immune system: in healthy and endotoxaemic mice
supplemented for a short time with FOS, B cell numbers were
increased in the PP
(50)
. Several studies report an increase in
intestinal or faecal IgA levels upon supplementation with
various b2-1 fructan preparations
(47,49,51 – 53)
. FOS supplemen-
tation increased total faecal IgA and IgA secretion by PP cells
in young mice
(51)
, and increased various intestinal measures of
IgA production in newborn mice, but did not alter B220
þ
IgM
þ
cell percentages in PP
(52)
. In rats, OF-enriched IN
increased caecal secretory IgA concentrations
(49)
. FOS in
combination with MOS increased ileal IgA in adult dogs
(53)
,
but there was no effect upon faecal IgA concentrations in
this same study
(53)
. Vaccine-specific faecal IgA was increased
in mice supplemented with a combination of OF and IN with
shorter-chain FOS removed and vaccinated with Salmonella
typhimurium, but total faecal IgA was not
(47)
. As IgA anti-
bodies present at the mucosal surface of the gut prevent adher-
ence of pathogens to the gut mucosa, these findings would
indicate improved health of the host upon b2-1 fructan sup-
plementation. However, several other studies do not show an
effect of b2-1 fructan supplementation on intestinal or
faecal IgA levels. Faecal and ileal Ig concentrations were
not altered in adult dogs fed FOS in combination with
MOS
(54)
. No effect of IN with shorter-chain FOS removed
or OF on faecal IgA concentrations was observed in mice or
hypoallergenic dogs
((46,55)
, and there was no effect of FOS
on IgA in the small intestine of piglets
(56)
. Thus, there is
some disagreement about the effects of b2-1 fructans on
IgA levels in the gastrointestinal tract, with three out of the
four mouse models showing an enhancement
(47,51,52)
and a
single study reporting no effect
(46)
. These studies were all in
young mice. None of the three studies that were conducted
in adult dogs showed an effect upon faecal IgA concen-
trations
(53 – 55)
, but one did show an effect upon ileal IgA con-
centration
(53)
. Thus it seems that the animal used and age may
be important in determining whether or not prebiotic sup-
plementation is beneficial on this aspect of immune function.
There may be a greater effect in younger animals as their gut
immune system is still developing and may therefore be more
susceptible to modulation. Other explanations for why there is
disparity in the results reported could include (1) that faecal
IgA may not be an accurate marker of what is happening
inside the gut, and (2) that the level of IgA that is reported
would depend, perhaps, on the site of the gut at which IgA
is measured. If b2-1 fructans enhance the immune system
through promotion of the growth of beneficial members of
the gut microbiota, and if a prebiotic, by definition, is specific
with respect to the beneficial bacteria it stimulates, then there
will be parts of the gut where these beneficial bacteria are
most abundant and therefore where the largest effect upon
the immune response would be observed. This may partly
explain why results reporting IgA at different locations vary.
b2-1 Fructan supplementation has been reported to have
effects upon T cell subsets and function, but these effects
vary depending upon the anatomical site of origin of the
cells, and the animal model used. The number of T cells in
the MLN of rats was increased upon OF or IN supple-
mentation
(45)
. The proportions of CD4
þ
cells (expressing
CD45R
þ
) and CD5
þ
cells in MLN were increased in adult
dogs supplemented with FOS combined with other fermenta-
ble fibres, but the proportion of intra-epithelial, PP and
lamina propria CD8
þ
cells was increased
(48)
. Thus a decrease
in the CD4
þ
/CD8
þ
ratio in the lamina propria cells was
observed
(48)
. In contrast, the CD4
þ
/CD8
þ
ratio was increased
in PP of endotoxaemic mice fed FOS
(50)
, and there was no
effect on CD4
þ
or CD8
þ
T cells in the MLN of rats supple-
mented with OF-enriched IN
(49)
. Responses of T cells to mito-
gens were increased for intra-epithelial lymphocytes and
MLN, but decreased for PP and lamina propria cells in dogs
supplemented with FOS plus fermentable fibres
(48)
, and no
effect of OF-enriched IN was seen on MLN or PP lymphocyte
proliferation in rats
(49)
. Enhancement of T cell cytokine pro-
duction has been reported, with an increase in IL-10 and inter-
feron (IFN)-gproduction from stimulated PP CD4
þ
T cells
seen in FOS-supplemented female mice, and high levels of
IL-5 and IL-6 secretion from these cells was also main-
tained
(51)
. IL-10 production from PP and MLN, and IFN-g
production from PP, was also increased in rats with
OF-enriched IN supplementation
(49,57)
; however, cytokine
production in MLN was not altered
(49)
. Taken together these
findings do not present a clear picture of the effects of b2-1
fructans on T cell numbers in GALT or on T cell responses.
It is possible that the effects of prebiotic supplementation
upon cell-mediated immunity in the GALT are dependent
upon the site of origin of the cells and the animal model used.
Systemic immune system.Innate immune system: the sys-
temic immune system has been more widely studied in the
context of prebiotic supplementation than the GALT.
As observed in the GALT, after OF or IN supplementation,
MHCII expression was increased in antigen-presenting cells
in the spleen and thymus of male rats
(45)
and mean fluor-
escence intensity of MHCII
þ
cells in spleen of mice also
increased, although percentage of MHCII
þ
cells did not
change here
(47)
. No measures of macrophage activity in the
systemic immune system have been recorded with b2-1 fruc-
tan supplementation. No effect upon monocyte or eosinophil
numbers in the blood was reported when aged dogs were sup-
plemented with chicory alone or in combination with MOS,
although a non-significant increase in neutrophil concen-
trations was seen
(58)
, and phagocytic activity of monocytes
and neutrophils in the blood or spleen was not altered upon
OF-enriched IN supplementation in rats
(49)
. FOS did not
affect whole blood phagocyte activation in piglets infected
with Salmonella typhimurium, although when given in a syn-
biotic (a mixture of a probiotic and a prebiotic), this marker
was increased
(56)
. FOS in combination with MOS did not
affect blood neutrophil numbers of adult dogs in one
study
(53)
but this supplement decreased neutrophil numbers
in another study
(54)
. This could be due to the use of different
doses of FOS: in the later study a higher dose of FOS was
given. Thus, in the systemic immune system, there seems to
be little effect of b2-1 fructans upon phagocytic function.
NK cytotoxicity in the peripheral blood was not altered by
FOS supplementation in adult dogs
(48)
, similar to the effects
seen in the GALT. However, in the spleen, a preparation of
A. R. Lomax and P. C. Calder640
British Journal of Nutrition
IN, with shorted-chain FOS removed, in combination with OF
increased NK activity of splenocytes in female mice
(46)
, and
OF-enriched IN increased NK cell-like cytotoxic function in
the spleen of male rats
(57)
, and the same supplement
non-significantly increased this function in blood mononuclear
cells in another study by the same group
(49)
. Thus, in the
spleen, at least, NK cell function may be enhanced by OF
or IN supplementation.
Adaptive immune system: in adult dogs, the proportion of B
cells in the peripheral blood was decreased when a high
fermentable fibre diet including FOS was fed
(48)
. The majority
of studies measuring the effect of b2-1 fructans on serum
Ig show no effect. This was observed in murine
(23,51)
and
canine
(53 – 55,58)
models, with supplementation of FOS alone,
FOS in combination with MOS, IN alone or IN in combination
with GOS or MOS. Antibodies measured included total serum
Ig, IgA, IgE, IgG, IgG2a, IgM and vaccine-specific antibodies
to influenza vaccination (total IgG, IgG1, IgG2a). Two studies
report a decrease in serum antibody concentrations upon OF sup-
plementation. A study in dogs showed that the proportion of B
cells in the peripheral blood was decreased with a high fermen-
table fibre diet
(48)
, and a study in mice demonstrated that FOS
supplementation was associated with a decrease in serum
IgG
1
(51)
. Just one study reports an increase in vaccine-specific
plasma IgG levels in mice vaccinated with Salmonella typhimur-
ium, although no effect on total serum IgG was observed
(47)
.
Thus, there seems to be little effect on systemic humoral immu-
nity by b2-1 fructan supplementation, and the studies which
have shown an effect have mostly shown a suppressive effect,
in contrast to the GALT where the results suggest that this
aspect of immune function may be enhanced.
T cell subpopulations may be altered with b2-1 fructan sup-
plementation. T cell numbers were increased in the spleen and
thymus of rats
(45)
. In the blood of adult dogs supplemented
with FOS, the CD4
þ
/CD8
þ
ratio was increased
(48)
. In contrast,
supplementation with OF-enriched IN decreased the spleen
CD4
þ
/CD8
þ
ratio in rats
(57)
. In mice, IN with shorter-chain
FOS removed or OF had no effect on lymphocyte subsets
(CD4
þ
and CD8
þ
percentages and or CD4
þ
/CD8
þ
ratio) in
the spleen or thymus
(46)
. Neither was there any effect of
OF-enriched IN on numbers of CD4
þ
or CD8
þ
T cells in
the spleen and blood of rats
(49)
, or of OF in combination
with IN with shorter-chain FOS removed on the percentage
of spleen cell subsets (CD4
þ
, CD8
þ
, B220
þ
, CD11b
þ
or
CD11c
þ
) in mice
(47)
. Thus, although some studies show that
b2-1 fructans may alter T cell subpopulations in the blood
and spleen, other studies report no effect on these measure-
ments in the spleen, thymus and blood.
Vaccine-induced splenocyte proliferation was not altered
in mice supplemented with a combination of GOS and IN
with shorter-chain FOS removed
(23)
. Neither was lymphocyte
proliferation altered in the spleen of rats supplemented with
OF-enriched IN
(49)
nor splenocyte proliferation in mice
vaccinated against Salmonella typhimurium and supplemented
with OF in combination with IN with shorter-chain FOS
removed
(47)
. Thus, lymphocyte proliferation in the spleen
appears not to be susceptible to modification by b2-1 fructans.
As in the GALT, T cell cytokine production may be altered
with b2-1 fructan supplementation: IFN-gproduction from
spleen CD4
þ
T cells was increased in mice supplemented with
FOS, although IL-5 and IL-6 production were decreased
(51)
,
and IL-12 and IFN-gproduction from splenocytes was
increased upon supplementation with a combination of OF and
IN with shorter-chain FOS removed in mice, although TNF-a
production was not altered
(47)
. There was no effect of OF-
enriched IN supplementation in rats upon IL-10 production by
splenocytes
(57)
, or upon cytokine production in the spleen
(49)
.
Blood IL-2 and IL-4 concentrations were increased upon IN
or OF supplementation in rats
(45)
. Thus, the limited number
of studies reporting T cell-derived cytokine production in ani-
mals receiving b2-1 fructans suggest that some modification
occurs. Why T cell cytokine production should be altered
when T cell proliferation is not affected is not clear. The delayed
type hypersensitivity response represents the summation of
a cell-mediated immune response to an antigenic challenge,
largely representing antigen-presenting cell and T cell function.
Therefore the observation that the delayed type hypersensitivity
response to influenza vaccine was increased when GOS and IN
with shorter-chain FOS removed were supplemented to mice
(23)
supports the findings of improved T cell cytokine production
with prebiotics.
Studies in man
Twelve studies that included supplementation with b2-1 fruc-
tans, either alone or in combination with other components, on
the human immune system were identified; these have mainly
measured aspects of the systemic immune system, via blood
immune markers and immune cell responses, and are summar-
ised in Table 2. Four of these studies investigated the effects of
b2-1 fructans alone
(24,59 – 61)
and five investigated supplements
that contain b2-1 fructans combined with antioxidants, vita-
mins, minerals, other prebiotics and fats
(62 – 66)
. Thus, it is dif-
ficult to determine whether the effects that were observed were
due to b2-1 fructans, or to another component of the sup-
plement. The remaining three studies investigated synbio-
tics
(67 – 69)
, but did not include a prebiotic alone group, and
so will be considered separately.
Innate immune system. A decrease in monocyte and
granulocyte phagocytosis of Escherichia coli was observed
when elderly adults resident in a nursing home were supple-
mented with OF for 3 weeks, although no control group was
included in this study making it difficult to interpret the find-
ings
(24)
. However, the finding of decreased phagocytosis is in
contrast to what was observed in senior dogs and adult rats,
where no modification of blood monocyte concentrations or
phagocytosis was seen
(49,58)
and to the findings of Seidel
et al.
(64)
of no effect on phagocytosis of E. coli by granulocytes
taken from young adult males consuming bread containing IN.
Neither OF
(24)
nor a bread containing IN
(64)
affected NK
cell numbers in human blood. To our knowledge there have
been no reports of the effect of b2-1 fructans on human NK
cell activity.
Adaptive immune system. The percentage of blood B cells
(defined as CD19
þ
) was increased in young male adults after
consumption of a bread containing IN
(64)
. B cell number was
increased in elderly residents of a long-term care facility
supplemented with FOS
(63)
. Thus there is some consistency
in findings in man regarding the effect of b2-1 fructans on
B cell numbers (an increase), but this is in contrast to obser-
vations in adult dogs, where B cell numbers in the blood
were decreased
(48)
.
Prebiotics and immunity 641
British Journal of Nutrition
Table 2. Effect of b2-1 fructans on immune function in man
Reference no. Prebiotic(s) used Subjects studied Findings
59 Oligofructose and inulin (0·2 g/kg
body wt/d for 10 weeks)
Healthy infants; age 8 months; immunised
with measles vaccine 4 weeks into the
trial; n24 in prebiotic group; n25 in
control group
"Post-vaccination total IgG levels in blood
24 Oligofructose (8 g/d for 3 weeks) Elderly adults in a care home; mean age
85 years; male and female; n19; no
control group
"% of peripheral blood T, CD4
þ
T and CD8
þ
T cells
#Monocyte and granulocyte phagocytosis of Escherichia coli
#IL-6 mRNA expression in peripheral blood mononuclear cells
No effect on:
Total number of leucocytes, activated T lymphocytes or NK cells in blood
60 Oligofructose and inulin (6 g/d for
28 weeks)
Elderly free-living adults; age ^70 years;
immunised with influenza and pneumo-
coccal vaccines 2 weeks into the trial;
n20 in prebiotic group; n23 in control
group
"Antibody response to influenza B virus and Streptococcus pneumoniae
in both prebiotic and control groups
No effect on:
Serum proteins, albumin, C-reactive protein, Ig (IgA, IgG, IgM), salivary secretory IgA
Serum antibody titres against influenza A virus
IL-4 and IFN-gproduction by cultured peripheral blood mononuclear cells
Stimulated lymphocyte proliferation
61 Oligofructose (in cereal sup-
plemented with 3·6 % w/w oligo-
fructose ¼0·55 g/d for 6 months)
Peruvian infants; aged 6–12 months;
immunised with Haemophilus influenzae
type B vaccine 5 months into the trial;
n129 in prebiotic group; n122 in control
group
No effect on:
Post-vaccination antibody response to H. influenzae type B (measured at 1
month post-vaccination)
67 Oligofructose and inulin (2:1 ratio;
6 g/d for 1 year) Included in the
formula were also protein, fat,
carbohydrate, vitamin E, vitamin
B
12
, thiamine, folic acid, ribofla-
vin, pyridoxine, other nutrients
and L. paracasei
Elderly free-living adults; age ^70 years;
immunised with influenza and pneumo-
coccal vaccines 4 months into the trial; n
30 in control group; n30 in experimental
group
At 4 months follow up:
"NK activity
Prevention of the #in proportion of T cells with NK activity that was seen in the control group
No effect on any other lymphocyte subpopulation
No significant effect on lipopolysaccharide-stimulated mononuclear cell production of IL-1,
TNF-aor IL-6
After vaccination:
Prevention of the #in IL-2 production by mononuclear cells seen in the control group
No effect on:
IFN-gproduction after influena antigen stimulation
Delayed type hypersensitivity
Magnitude of the rise in influenza antibodies or pneumococcus antibodies
62 Fructo-oligosaccharides (4·95 % of
the energy intake of the 226·8 g
(8 oz) formula/d for 26 weeks)
The formula also contained
antioxidants (vitamins C, E and
b-carotene), B vitamins, zinc,
selenium, other vitamins and
minerals, and structured TAG
Adults aged ^65 years; assisted-living
and independent-living; immunised
with influenza vaccine 2 weeks into
the trial; n18 in control group; n16
in experimental group
Improved response to some vaccine components
"Lymphocyte proliferation to influenza vaccine components
65 Galacto-oligosaccharides and inulin
with shorter-chain fructo-oligosac-
charides removed (ratio 9:1);
0·6 g/100 ml formula for 32 weeks
Also looked at B. animalis
Newborn infants; non-breast-fed; n19 in
prebiotic group; n19 in probiotic group;
n19 in control group (standard infant
formula)
Trend for "faecal secretory IgA (statistically significant at 16 weeks)
A. R. Lomax and P. C. Calder642
British Journal of Nutrition
Table 2. Continued
Reference no. Prebiotic(s) used Subjects studied Findings
63 Fructo-oligosaccharides (4·95 % of
the energy intake of the 240 ml
formula/d for 10 weeks) The for-
mula also contained antioxidants
(vitamins C, E and b-carotene), B
vitamins, zinc, selenium, other
vitamins and minerals, and struc-
tured TAG
Frail adults aged ^65 years; living
in long-term care facilities; immunised
with influenza vaccine 4 weeks into
the trial; n40 in control group; n52
in experimental group
Improved response to some vaccine components
"B cells
#Memory cytotoxic T cells
"Influenza-activated lymphocytes (CD69 and CD25) (this was due to
changes in CD2
2
T cells and CD2
2
CD8
2
Th cell populations)
#IL-6 and a trend for #IL-10 production by phytohaemagglutinin-stimulated mononuclear
cells at week 6 post-vaccination
#Fever
Non-significant "in NK T cells (expressing CD56
þ
/CD57
þ
, CD28
þ
and CD3
þ
)
Non-significant "in naı
¨ve Th cells
No effect on:
Geometric mean antibody titres
Leucocyte counts, percentage of lymphocytes and T cell subsets (CD4
þ
or CD8
þ
)
68 Synbiotic containing oligofructose-
enriched inulin (12 g/d for 12
weeks) plus Lactobacillus
delbreuckii subsp. rhamnosus
GG and Bifidobacterium lactis
Bb12
Adults; colon cancer and polypectomised
patients; n38 in test group; n36 in
placebo group
Prevented increased IL-2 secretion from stimulated peripheral blood mononuclear cells
in polypectomised patients, but not in cancer patients
"IFN-gproduction from stimulated peripheral blood mononuclear cells in colon cancer
patients, but not in polypectomised patients
69 Synbiotic containing oligofructose-
enriched inulin (10 g/d for 12
weeks) plus L. rhamnosus GG
and B. lactis Bb12
Adults; colon cancer and polypectomised
patients; n38 in test group;
n36 in placebo group
"IL-2 secretion by activated mononuclear cells
"IFN-gproducing capacity of peripheral blood mononuclear cells at 12 weeks compared
to 6 weeks in cancer patients
No effect on:
% of phagocytically active neutrophils and monocytes and their phagocytic
intensity in cancer and polypectomised patients
% of neutrophils that produced reactive oxygen species and the intensity of this production
in cancer or polypectomised patients
Lytic activity of NK cells in cancer or polypectomised patients
Production of IL-10, IL-12 and TNF-afrom activated peripheral blood
mononuclear cells in cancer or polypectomised patients
IFN-gproduction by mononuclear cells in polypectomised patients
IL-2 secretion by activated peripheral blood mononuclear cells in cancer patients
PGE
2
and TGF-b1 concentrations in faecal water in cancer or polypectomised patients
64 Inulin (4 % w/w of a bread, which
also contained other prebiotics
with/without antioxidants; approxi-
mate intake 9 g inulin/d for 5
weeks)
Adults; male; mean age 27 years; smokers
and non-smokers; n19 in prebiotic
group; n19 in prebiotic plus antioxidant
group
Twenty-three immunological parameters were measured in the peripheral blood, most of which
were unchanged by either the prebiotic or the prebiotic plus antioxidant bread. However:
"% CD19 (B) cells after prebiotic bread
#% ICAM-1 bearing lymphocytes after prebiotic bread
#% CD3
þ
NK
þ
cells after prebiotic and prebiotic plus antioxidant bread
"CD3
þ
HLA-DR
þ
(activated T cells) after prebiotic bread
No effect upon:
Numbers of leucocytes
Phagocytosis of E. coli by granulocytes
Numbers of CD3, CD4, CD8, CD4:CD8, CD57, CD8
þ
, CD4
þ
CD25
þ
, CD122, CD4
þ
CD54
þ
Numbers of NK cells
Numbers of activated T cells (CD25)
Prebiotics and immunity 643
British Journal of Nutrition
In a study of healthy free-living elderly adults, there was no
effect of a combination of OF and IN upon serum Ig concen-
trations (IgA, IgG, IgM)
(60)
, which is agreement with several
studies in laboratory animals which show no effect of b2-1
fructans on these
(23,51,53 – 55,58)
. In the same study, there was
no effect of the combination of OF and IN upon salivary
secretory IgA levels
(60)
. In newborn infants supplemented
with a mixture of GOS and IN with shorter-chain FOS
removed in their formula, an increase in faecal secretory
IgA levels was seen
(65)
, which fits with the findings from
animal studies which show an enhancement of the antibody
response in the GALT by prebiotics
(47,49,51 – 53)
.
The antibody response to vaccination is considered to be the
gold standard for measuring the functioning of the immune
system in vivo, based on its biological relevance, sensitivity
and practical feasibility
(70)
. Thus several human studies use
this marker, but these have generated mixed results. In healthy,
free-living elderly adults, OF plus IN increased the antibody
response to influenza B virus and Streptococcus pneumoniae
after vaccination, yet this was also seen in the control
group
(60)
. In the same study, there was no effect of the sup-
plementation upon antibody titres against influenza A virus. In
a study of elderly adults, FOS supplementation increased the
number of subjects with a four-fold or greater increase in
serum antibody titre, and an antibody titre of forty or more, to
the A/Beijing component of the influenza vaccine 6 weeks
after the vaccine was administered
(62)
, but this was not seen
for the other components of the vaccine. In a group of elderly
adults resident in long-term care facilities and vaccinated with
influenza, FOS supplementation did not alter the geometric
mean antibody titre, but did increase the number of subjects
with an antibody titre greater than 100 to the H1N1 component
6 weeks after the vaccine was given
(63)
. A study in 8-month-old
infants supplemented with OF plus IN reported an increase in
post-vaccination measles IgG levels in the blood
(59)
, but in
Peruvian infants given OF-enriched cereal, and immunized
against influenza, there was no effect upon post-vaccination
antibody titres to Haemophilus influenzae type B
(61)
. Taken
together, these studies suggest that b2-1 fructans may increase
the response to some vaccines or vaccine components but not
all. This conclusion is consistent with that from animal
studies
(23,47)
.
The percentages of peripheral blood T cells, CD4
þ
T cells
and CD8
þ
T cells were increased in elderly nursing home resi-
dents upon OF supplementation, although there was no effect
on the number of activated T cells
(24)
. No effect of FOS was
seen on percentages of lymphocytes, or CD4
þ
or CD8
þ
T cells
in elderly adults resident in long-term care facilities, although
influenza-activated T cells were increased and memory
cytotoxic T cells were decreased, and NK T cells were non-
significantly increased
(63)
. Likewise, there was no effect of
consumption of a bread containing IN on the percentage of
T, activated T, CD4
þ
or CD8
þ
cells in the blood of young
male adults
(64)
. However, the percentage of activated T cells
(defined as CD3
þ
HLA-DR
þ
) increased while that of NK
T cells (defined as CD3
þ
NK
þ
) decreased
(64)
. This mixed
picture of effects of b2-1 fructans on blood lymphocyte
subsets is similar to that seen in laboratory animals
(48,49)
.
Lymphocyte proliferation to influenza vaccine components
was increased in elderly adults supplemented with FOS
(62)
,
but in another study in elderly adults, there was no effect of
Table 2. Continued
Reference no. Prebiotic(s) used Subjects studied Findings
66 Inulin (0·88 g/d) þgalacto-oligo
saccharides (8·18 g/d for 15
weeks; last trimester of
pregnancy)
Pregnant women; n17 in test group,
median age 33 years; n16 in control
group, median age 35 years
No effect on:
Ratio of CD4
þ
to CD8
þ
cells in cord blood
% CD4
þ
CD45RA
þ
, CD8
þ
CD45RA
þ
, CD4
þ
CD45RO
þ
, CD4
þ
CKR
þ
, CD8
þ
CKR
þ
,
CD4
þ
CD45RA
þ
CKR
þ
or CD8
þ
CD45RA
þ
CKR
þ
cells in cord blood
CD69 and CD25 expression on CD4 þsubsets in cord blood (non-stimulated)
Frequency of CD4
þ
CD25
high
regulatory T cells
Production of TNF-a, IL-1, IL-6, IL-8, MCP-1, MIPb, IFN-g, IL-2, IL-4 or IL-10 by
cultured cord blood
MCP-1, monocyte chemoattractant protein 1; NK, natural killer; TGF, transforming growth factor; ", increase/increased; #, decrease/decreased; MIP, macrophage inhibitory protein.
A. R. Lomax and P. C. Calder644
British Journal of Nutrition
OF plus IN upon stimulated lymphocyte proliferation
(60)
.
Regarding cytokine expression, in elderly nursing home resi-
dents, OF supplementation decreased IL-6 mRNA expression
in blood mononuclear cells
(24)
, and in elderly adults resident in
long-term care facilities, IL-6 production by stimulated blood
mononuclear cells was decreased
(63)
. As an increase in IL-6 is
associated with the pro-inflammatory state associated with
ageing
(71)
, this could be considered a beneficial effect.
In healthy free-living elderly adults, there was no effect of
OF plus IN upon IFN-gand IL-4 secretion by cultured
mononuclear cells
(60)
. This is in contrast to a study in rats
that showed an increase in blood measurements of IL-4
(45)
.
A trend for a reduced IL-10 production from stimulated
blood mononuclear cells was observed upon FOS supplemen-
tation in the elderly
(63)
.
Synbiotics and the immune system in man. In a study of
adult colon cancer or polypectomised patients, OF-enriched
IN was given in combination with Lactobacillus rhamnosus
GG and Bifidobacterium lactis Bb12. The synbiotic prevented
the increase in IL-2 secretion by mononuclear cells from
polypectomised patients that was seen in control patients,
and also increased IFN-gproduction by mononuclear cells
in colon cancer patients
(68,69)
. However, the synbiotic had no
effect on several other immune markers in either cancer or
polypectomised patients, including percentages of phagocyti-
cally active neutrophils and monocytes and their phagocytic
intensity, percentage of neutrophils producing reactive
oxygen species and the intensity of production, lytic activity
of NK cells or production of IL-10, IL-12 and TNF-aby acti-
vated blood mononuclear cells. It is interesting to note that in
another population, the healthy elderly immunised with influ-
enza and pneumococcal vaccines, some of these findings
are replicated. OF and IN in combination with Lactobacillus
paracasei prevented the decrease in IL-2 production by mono-
nuclear cells seen in controls after vaccination, and there was
no effect upon TNF-aproduction
(67)
. However, other findings
differ, such as an increase in NK activity and no effect on
IFN-gproduction with influenza virus antigen stimulation.
There was no effect on IL-6 or IL-1 production by stimulated
blood mononuclear cells, or on lymphocyte subpopulations
(67)
.
The decrease in numbers of T cells with NK activity that was
seen in the control group was prevented with the supplemen-
tation
(67)
. After the vaccinations were given there was no
effect of the synbiotic on the magnitude of the increase in
anti-influenza vaccine or anti-pneumococcus vaccine anti-
bodies, or on the delayed type hypersensitivity response
(67)
.
Prebiotics and infection
If prebiotics improve host immune defences, then it would be
expected that they decrease susceptibility to and/or severity of
infection. This section will review studies in experimental
animals and in man that investigate the effect of increased
consumption of b2-1 fructans on infectious outcomes.
Studies in laboratory animals
Seventeen animal studies of infection were identified (two of
which used synbiotics), and b2-1 fructan supplementation
generally appears to be beneficial in the models used (Table 3).
A series of studies using piglets infected with Oesophagos-
tomum dentatum or Trichuris suis showed decreases in Oeso-
phagostomum dentatum and Trichuris suis faecal egg counts,
intestinal worm recovery, size of worms and the female
worm’s ability to reproduce after IN supplementation
(72 – 77)
.
Another study, in Salmonella typhimurium-infected puppies,
showed that OF or IN decrease the severity of enterocyte
sloughing, suggesting a reduction in epithelial damage com-
pared to controls
(78)
. FOS supplementation increased survival
in a hamster model of Clostridium difficile infection
(79)
and in
murine models of Listeria monocytogenes and Salmonella
typhimurium infection both IN and OF increased survival
(80)
.
In the latter study, IN was more effective than OF at decreas-
ing mortality. FOS in drinking water decreased the shedding
of Salmonella typhimurium in the faeces of piglets infected
with Salmonella typhimurium, although the effect was not
significant
(81)
, and FOS prevented diarrhoea induced by
Salmonella typhimurium in piglets
(82)
. FOS decreased diar-
rhoea and increased survival rates in piglets infected with
E. coli
(83)
. These studies provide a consistent picture that
b2-1 fructans do improve host resistance to bacterial
infections.
In contrast to the studies described earlier, a series of
studies investigating OF supplementation in calcium-deficient
rats suggest increased Salmonella typhimurium colonisation
and translocation, and increased mucosal irritation
(84 – 87)
.
These findings may be explained by the calcium-deficient
state of the rats used, since a direct comparison of OF in rats
fed calcium-deficient and calcium-sufficient diets showed
different effects
(86)
. While the calcium-deficient animals dis-
played increased susceptibility to S. typhimurium, calcium-
sufficient animals did not. Thus, the relevance of the findings
to animals or man that are not calcium-deficient is limited.
Two studies have investigated the use of synbiotics in
animal models of infection. A study in mice pups infected
with rhesus rotavirus demonstrated that OF in combination
with Bifidobacterium bifidum and Bifidobacterium infantis
reduced the duration of diarrhoea, although the synbiotic
was no more effective than the probiotic alone
(88)
. Rotavirus
infects the enterocytes of the small intestine, but prebiotics
and probiotics have their effects mainly in the large intestine.
Thus, although improving the health of the large intestine is
likely to be useful in diarrhoea, prebiotics may not be more
helpful than a probiotic alone because of limited effects in
the small intestine. Although piglets infected with Salmonella
typhimurium were shown to have decreased shedding of
Salmonella typhimurium in faeces when supplemented with
FOS, FOS given as part of a synbiotic had no effect on
Salmonella typhimurium infection
(81)
.
Studies in man
Infants and children. Several studies have shown some
benefit from b2-1 fructans on common childhood and acute
diarrhoea (Table 4). Although OF-enriched cereal had no
effect upon frequency or duration of common childhood
diarrhoea in non-breast-fed American infants, it reduced the
severity
(89,90)
. In another study episodes of common childhood
diarrhoea were reported to be reduced in healthy infants sup-
plemented with OF
(91)
. In Indonesian children aged 1 14
Prebiotics and immunity 645
British Journal of Nutrition
Table 3. Effects of b2-1 fructans on infectious outcomes in animal models
Reference
no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
83 Fructo-oligosaccharides (3 g/d) Piglets (7 d old); infected with Escherichia coli #Symptoms of anorexia, pyrexia, dehydration and diarrhoea
"Survival from E. coli infection
72 Inulin (7 % w/w diet) Pigs (male, 12 weeks old); pathogen-free;
infected with Oesophagostomum dentatum
and Ascaris suum
#O. dentatum faecal egg count
#Total intestinal O. dentatum worm recovery, but when different
parts of the large intestine were investigated, changes were not
always significant
No effect upon A. suum prevalence or fecundity
79 Fructo-oligosaccharides (30 g/l drinking water) Hamsters (female); infected with Clostridium difficile #Mortality
81 Fructo-oligosaccharides (1 % w/w of diet
in water/feed), with/without probiotic mix
(Ferlac2) of Lactobacillus acidophilus,
L. rhamnosus,Enterococcus faecium,
Streptococcus
thermophilus and L. bulgaricus
Piglets (21 d old); infected with S. typhimurium Fructo-oligosaccharides in drinking water non-significantly #shedding of
S. typhimurium in faeces
No effect:
On the number of S. typhimurium in the mesenteric lymph nodes
Of the synbiotic on S. typhimurium infection
73 Inulin with shorter-chain fructo-oligosaccharides
removed (6 % w/w diet) in combination with
sugarbeet fibre
Pigs (pathogen-free, 16 weeks old); infected with
O. dentatum
#O. dentatum faecal egg count
At 3 and 12 weeks post-infection #total O. dentatum worm numbers in
large intestine
At 3 and 12 weeks post-infection #size of worms
#Female worm fecundity
80 Oligofructose or inulin (10 % w/w diet) Mice (female, 5 weeks old); infected with Candida
albicans,orListeria monocytogenes or
S. typhimurium
#Density of C. albicans in small intestine with oligofructose or inulin
#Mortality from L. monocytogenes with oligofructose or inulin (0 %
mortality with inulin; 12 % mortality with oligofructose; 28 % mortality
with control)
#Mortality from S. typhimurium with inulin (60 % mortality with inulin;
75 % mortality with oligofructose; 85 % mortality with control)
88 Oligofructose (1·25 g/l drinking water)
in combination Bifidobacterium bifidum
and B. infantis
Mice (pups); infected with Rhesus rotavirus Oligofructose did not have any additional benefit
compared to when the probiotic was given alone, but both treatments:
#Duration of diarrhoea
82 Fructo-oligosaccharides (7·5 g/l drinking water) Piglets (2 d old); infected with S. typhimurium #Diarrhoea induced by S. typhimurium
85 Oligofructose (4 % w/w diet) Rats (male, 8 weeks old); pathogen-free;
infected with S. enteritidis; calcium deficient
#Faecal shedding of S. enteritidis (thus improved colonisation
resistance to S. enteritidis)
"Translocation ( "Salmonella counts in the liver and spleen)
"Faecal mucin excretion
"Myeloperoxidase activity in caecum and colon, but not in the ileum
74 Inulin (6 % w/w diet) in combination
with sugarbeet fibre
Pigs (13 weeks old); pathogen-free; infected with
O. dentatum
#Worm numbers in anterior and middle parts of large intestine
75 Inulin alone (16 % w/w diet) or in
combination with sugarbeet fibre
(6 % w/w diet)
Pigs (10 weeks old); pathogen-free;
infected with O. dentatum
At 13 weeks post-infection, pigs fed the inulin alone diet had a 99 % #in
O. dentatum faecal egg count
Total colonic worm recovery was #by 97 % in inulin alone group and
by 86 % in inulin plus sugarbeet fibre group
84 Oligofructose (3 or 6 % w/w diet) Rats (male, 8 weeks old); specific pathogen-free;
infected with S. enteritidis; calcium deficient
"Salmonella number in caecal contents and "caecal mucosal
colonisation by Salmonella (dose-dependent)
"Translocation
#Animal growth
"Faecal mucin excretion
86 Oligofructose or inulin (6 % w/w diet) Rats (male, 8 weeks old); specific pathogen-free;
infected with S. enteritidis; calcium deficient
Oligofructose and inulin:
"Caecal colonisation of Salmonella
"Translocation
A. R. Lomax and P. C. Calder646
British Journal of Nutrition
years, the duration of acute diarrhoea was reduced with FOS
supplementation
(92)
, and incidence of acute diarrhoea was
also reduced in infants who received an infant formula
containing GOS and FOS
(93)
. Incidence of upper respiratory
tract infections was also reduced in the group consuming
this formula
(93)
. Intestinal permeability was improved in
infants fed with a formula containing GOS and IN as
compared to a control formula
(94)
. A trial carried out in
Peruvian infants found no effect of OF on the occurrence or
prevalence of diarrhoea
(61)
, and a trial in infants with
diarrhoea showed no benefit of including IN and FOS in the
rehydration solution on duration of diarrhoea
(95)
.
In infants, there was a non-significant trend for a reduction
in respiratory tract infections in those receiving a formula
containing a synbiotic that included a GOSFOS mixture
compared to those receiving the control formula
(96)
. A study
in Chilean children colonised with Helicobacter pylori
showed a reduction in the number colonised in both synbiotic
and probiotic groups, but there was no difference between
these two groups
(97)
.
Taken together data from studies using prebiotics in
infants and children are suggestive of a reduction in incidence
or duration of some infections.
Adults. Three out of the six studies identified show signifi-
cant benefit of b2-1 fructans on infections in adult human
subjects (Table 4). These studies showed a decrease in relapse
rate of in-patients with Clostridium difficile-associated
diarrhoea
(98)
, decreased upper respiratory tract infections in
older adults post-influenza vaccine
(62)
, and decreased respiratory,
skin, gastrointestinal and genitourinary infections in
older adults immunised with influenza and pneumococcal
vaccines
(67)
. No effect was seen when OF was supplemented
to in-patients receiving broad-spectrum antibiotics on anti-
biotic-associated diarrhoea caused by Clostridium difficile
or other causes
(99)
. There was no significant effect of FOS sup-
plementation upon travellers’ diarrhoea in people holidaying
to areas of medium/high risk of diarrhoea, although there
was a non-significant decrease in diarrhoea and an increase
in feelings of well-being
(100)
. In burns patients, OF did not
improve a variety of measures of the severity or duration of
infections
(101)
. In healthy adults, OF had no effect upon
faecal mucin excretion
(102)
. In men consuming a diet with
limited calcium, intestinal permeability did not differ between
the control and OF supplement periods, although faecal
mucin excretion was increased with the addition of OF to
the diet
(103)
. In a study of patients on an enteral diet, IN had
no effect upon intestinal permeability
(104)
.
Most trials of synbiotics and infection in human adults
have been carried out in patients admitted to intensive care or
surgery wards (Table 4). Synbiotics appear to exert some ben-
eficial effects on infections in these patients
(105 – 107)
. In studies
where synbiotics have been compared with prebiotics alone,
synbiotics have been shown to be more beneficial in terms of
reducing length of antibiotic therapy and bacterial infections
in patients undergoing duodenal surgery
(108)
and liver transplan-
tation
(109)
. However, some of these studies report no effects
of synbiotics on other outcomes measured
(105,107)
. No effect
of a synbiotic was seen regarding bacterial colonisation to
lymph nodes or terminal ileal serosa, gastric colonisation or
septic complications in adult patients undergoing elective
abdominal surgery
(110)
.
Table 3. Continued
Reference
no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
87 Oligofructose (6 % w/w diet) Rats (male, 8 weeks old); specific
pathogen-free; infected with S. enteriditis;
calcium deficient
"Faecal mucin concentration
"Intestinal permeability before and after infection
"Translocation to extra-intestinal sites
In a separate experiment where rats were not infected with S. enteriditis,
oligofructose "mucin concentrations in caecal and colonic contents
and in the caecal mucosa, but not in ileal contents or in the ileal
or colonic mucosa
77 Inulin with shorter-chain
fructo-oligosaccharides
removed (6 % w/w diet)
in combination with sugarbeet fibre
Pigs (10 weeks old); pathogen-free; infected
with Trichuris suis
#Faecal egg counts
#Worm size
No effect at 8 weeks post-infection on worm counts, but at
12 weeks post-infection, worm counts were #
78 Short-chain oligofructose or inulin
(1 % w/w diet)
Puppies (12 weeks old, male and female);
infected with S. typhimurium
Both short-chain oligofructose and inulin:
#Severity of enterocyte sloughing (thus #epithelial damage)
Prevented the #in ileal Na
þ
-dependent glucose transport seen in controls
76 Inulin (16 % w/w diet) Pigs (10 weeks old); infected with T. suis #Faecal egg counts at 7 weeks post-infection
If pigs were switched from the control diet to the inulin diet, faecal
egg counts #
#Number of worms recovered in large intestine at 7 and 9 weeks
post-infection
#Fecundity of female worms at 7 and 9 weeks post-infection
", increase/increased; #, decrease/decreased.
Prebiotics and immunity 647
British Journal of Nutrition
Table 4. Effects of b2-1 fructans on infections in man
Reference
no. Prebiotic used Subjects studied Findings
104 Inulin (30– 37·5 g/d, for 1 week, in enteral
nutrition formula)
Patients receiving enteral nutrition for a variety of
reasons; aged 19–76 years; n9; no control
No effect upon intestinal permeability measured by
51
Cr-
EDTA absorption
89, 90 Oligofructose (in cereal supplemented with
3·6 % w/w oligofructose ¼1·1 g/d for 6 months)
American infants; non-breast-fed; aged
4–24 months; n63 in prebiotic group;
n60 in control group
#Occurrence of fever during diarrhoea
#Seeking of medical attention during fever
#Number of days of day-care missed because of
diarrhoea
#Occurrence of fever with cold symptoms
#Antibiotic use during respiratory illness
#Uncomfortable bowel movements
No effect on:
Diarrhoea frequency
Diarrhoea duration
100 Fructo-oligosaccharides (10 g/d for 2 weeks prior
to travel and 2 weeks whilst travelling)
Adult travellers to medium/high-risk areas of
diarrhoea; mean age 50 years; n117 in
prebiotic group; n127 in control group
"Feeling of well-being
Non-significant decrease in diarrhoea
92 Fructo-oligosaccharides (2 ·5– 5 g/d, depending
on age of child, for an unspecified period)
Indonesian children; aged 1–14 years; with acute
diarrhoea; n93 in prebiotic group;
n25 in control group
#Duration of diarrhoea in all ages
61 Oligofructose (in cereal supplemented with
3·6 % w/w oligofructose ¼0·55 g/d for 6 months)
Peruvian infants; immunised with Haemophilus
influenzae type B vaccine 5 months into the trial;
aged 6–12 months; n129 in prebiotic group;
n122 in control group
No effect on:
Occurrence of diarrhoea
Prevalence of diarrhoea
110 Oligofructose (32 g/d for 1 –2 weeks pre-surgery, and until
discharge from hospital) plus probiotics (Trevis capsules,
containing Lactobacillus acidophilus La5, L. bulgaricus,B.
lactis Bb12 and S. thermophilus)
Patients undergoing elective abdominal
surgery; median age 71 years; n72 in test group;
n65 in control group
No effect on:
Bacterial translocation to lymph nodes or terminal
ileal serosa
Gastric colonisation
Systemic inflammation (measured by serum C-reactive
protein, IL-6 or IgM serial antiendotoxin core antibody)
Septic complications
Length of hospital stay
95 Fructo-oligosaccharides and inulin (0·185 and 0·215 %,
respectively, of an oral re-hydration solution, also contain-
ing other non-digestible carbohydrates, until cessation of
diarrhoea)
Infants with diarrhoea and mild to moderate
dehydration; aged 1–36 months; male;
n70 in test group; n74 in control group
No effect on:
Duration of diarrhoea
Duration of hospital stay
Risk of vomiting
105 Oligofructose (15 g/d for the duration of hospital stay) plus
probiotics (L. acidophilus La5, B. lactis Bb12,
S. thermophilus and L. bulgaricus)
Adult patients admitted to intensive care units;
aged over 62–80 years; n45 in
test group; n45 in control group
After 8 d, patients receiving the synbiotic had significantly
reduced incidence of potentially pathogenic bacteria and
multiple organisms in nasogastric aspirates
No effect on:
Intestinal permeability
C-reactive protein levels
Septic complications
Mortality
Length of hospital stay
67 Oligofructose and inulin (2:1 ratio; 6 g/d for 1 year) Included
in the formula were also protein, fat, carbohydrate, vitamin
E, vitamin B
12
, thiamine, folic acid, riboflavin, pyridoxine,
other nutrients and L. paracasei
Elderly free-living adults; age ^70 years; immunised with
influenza and pneumococcal vaccines 4 months into the
trial; n30 in control group; n30 in experimental group
After vaccination:
#infections (respiratory, skin, gastrointestinal and
genitourinary)
97 Inulin (5 g/d, given in a synbiotic with
S. boulardi, for 8 weeks)
Children in Chile colonised by Helicobacter pylori;age
5–12 years; n62 in synbiotic group; n63 in probiotic
group (L. acidophilus LB); n57 in antibiotic group; n71
asymptomatic children with no treatment
H. pylori was eradicated in 66 % of the antibiotic group;
12 % of the synbiotic group and 6·5 % of the probiotic
group. The difference between the synbiotic and probiotic
groups was not significant
A. R. Lomax and P. C. Calder648
British Journal of Nutrition
Table 4. Continued
Reference
no. Prebiotic used Subjects studied Findings
62 Fructo-oligosaccharides (4·95 % of the energy intake of the
226·8 g (8 oz) formula/d for 26 weeks)
The formula also contained antioxidants (vitamins C,
E and b-carotene), B vitamins, zinc, selenium,
other vitamins and minerals, and structured TAG
Adults aged ^65 years; assisted-living and independent-
living; immunised with influenza vaccine 2 weeks into the
trial; n18 in control group; n16 in experimental group
#Median days of upper respiratory tract infections
98 Oligofructose (12 g/d during diarrhoea
and for 30 d after cessation)
Adult in-patients with C. difficile-associated diarrhoea;
n72 in test group; n70 in control group
#Relapse of diarrhoea (8·3 % prebiotic group relapsed
compared to 34·3 % of placebo)
99 Oligofructose (12 g/d until 7 d after ceasing antibiotic use) Adult in-patients receiving broad-spectrum antibiotics;
aged over 65 years; n215 in prebiotic group; n220
in control group
No effect on antibiotic-associated diarrhoea caused by
C. difficile or other causes
101 Oligofructose (6 g/d for 15 d) Second and third degree burns patients; n15
in control group, mean age 41·2 years; n16
in test group, mean age
38·6 years
No differences between groups regarding:
Measures of intestinal permeability
Length of hospitalisation
Number of surgical interventions
Rates of burn infection
Number of complications
109 Inulin (5 g/d for 14 d), given in combination with three other
fibres, or with the three other fibres plus Pediacoccus
pentoseceus,L. mesenteroides,L. paracasei and
L. plantarum
Adult patients undergoing liver transplantation; n33
in fibre plus probiotic group, mean age 53 years;
n33 in fibre only group, mean age 50 years
In those receiving fibres plus probiotics, as opposed to
those receiving fibres alone, there was:
#Duration of antibiotic therapy
#Incidence of post-operative infections (mostly upper
and lower urinary tract infections)
No difference between the groups regarding:
Length of hospital stay
CD4
þ
, CD8
þ
, CD19
þ
, or NK cells, CD4
þ
:CD8
þ
ratio or IgA
93 Galacto-oligosaccharides/fructo-oligosaccharides (9:1 ratio)
in infant formula (for 12 months)
Infants aged 15–120 d; n136 in test group; n145
in control group
#Incidence of acute diarrhoea
#Number of children with more than three episodes of
upper respiratory tract infections/year
#Number of children receiving more than two antibiotic
courses/year
94 Galacto-oligosaccharides and inulin Full-term infants; formula fed; n15 in test group; n
15 in control group; n30 in breast-fed group
Those receiving the GOS/inulin formula showed an
intestinal permeability similar to that of the breast fed
infants, and significantly different to that of the control
formula fed infants
106 Inulin (2·5 g/d for 15 d) plus three other fibres and
Pediacoccus pentoseceus,L. mesenteroides,
L. paracasei and L. plantarum
Adult multiple trauma victims admitted to surgical
intensive care units; n35 in test group, mean age 52·9
years; n30 in control group, mean age 55·9 years
#Systemic infection rate
#Septic complications
#Septic inflammatory response syndrome (procalcitonin,
C-reactive protein, malondialdehyde, TNF-aand IL-6)
#Severe sepsis
#Number of days of stay in the intensive care unit
#Number of days under mechanical ventilation
107 Oligofructose (30 g/d; duration not specified) plus
L. acidophilus La5, L. bulgaricus,
B. lactis Bb12 and S. thermophilus
Adult elective colorectal surgery patients; aged 53–81
years; n20 in synbiotic þneomycin þMBP group;
n22 in synbiotic þneomycin group; n22 in
neomycin þMBP group; n24 in MBP group
The synbiotic plus neomycin plus MBP group had #
incidence of bacterial translocation to MLN after bowel
mobilisation
No effect of the synbiotic upon:
Intestinal permeability
Inflammatory response (C-reactive protein or IL-6 levels)
Septic morbidity
Wound infections
Incidence of lower respiratory tract infections
Prebiotics and immunity 649
British Journal of Nutrition
Overall, studies of b2-1 fructans in adults are less convin-
cing of a benefit with respect to infections compared with
studies in infants and children. However, it appears that
b2-1 fructans are useful in this regard in some situations
(98)
and as a component of a synbiotic.
Prebiotics and inflammation
This section will review studies in experimental animals and
in man that investigate the effect of increased consumption
of b2-1 fructans on inflammatory outcomes.
Studies in laboratory animals
Ten studies were identified (two using synbiotics), with mostly
consistent results, showing positive effects of b2-1 fructans on
inflammation in animal models (Table 5).
Considering the reported effects of b2-1 fructans on T cell
numbers and function in animal models described pre-
viously
(45,48 – 51,57)
it is not surprising that they are effective
in colitis: four out of five rodent studies of colitis report a
decrease in inflammatory markers and the severity of disease
when animals were supplemented with b2-1 fructans. Three
studies using IN, FOS or OF-enriched IN in colitis models
in rats report reductions in mucosal damage, release of a
range of inflammatory mediators (such as PGE
2
, thromboxane
B
2
, leukotriene B
4
and pro-inflammatory cytokines) in differ-
ent parts of the gut, and various other markers of inflam-
mation
(21,25,111)
. A model of colitis in female mice showed
that FOS decreased disease activity index and damage to the
distal colon
(112)
. However, OF did not have an effect on
total macroscopic scores, or on caecal, proximal and distal
colon histological scores in a colitis model in male rats
(113)
.
b2-1 Fructans given as part of a synbiotic have also been
shown to have beneficial effects in rat models of colitis:
when IN was given along with Lactobacillus acidophilus
La5 and Bifidobacterium lactis Bb12, colonic inflammation
was reduced
(114)
, and OF-enriched IN given alone or in
combination with Bifidobacterium infantis reduced bacterial
translocation to MLN, colonic myeloperoxidase activity
(an indicator of inflammatory granulocyte infiltration) and dis-
ease activity index
(26)
.
Neonatal necrotising enterocolitis may be in part caused by
interactions between intestinal immaturity, inappropriate bac-
terial colonisation and infections
(115)
. Thus, from the known
beneficial microbiota-stimulating effects, and previously
described effects of b2-1 fructans on the immune system, it
is possible that b2-1 fructans could be of benefit in this dis-
ease. Indeed, in a quail model of neonatal necrotising entero-
colitis, OF decreased the occurrence and severity of intestinal
lesions, although the clostridial species that was used to
induce the colitis had an effect on the magnitude of this
effect
(22,116)
.
In a rat model of allergic airway eosinophilia, FOS provided
no benefit, regarding total cell, eosinophil, macrophage
or lymphocyte numbers in bronchoalveolar lavage fluid, or
IL-4, IL-5 or IFN-gmRNA levels in lung tissue
(117)
.
The lack of effect of FOS on airway inflammation may be
due to the distance of this compartment from the gastrointes-
tinal tract.
Table 4. Continued
Reference
no. Prebiotic used Subjects studied Findings
102 Oligofructose (25– 30 g/d for 2 weeks) Adults; mean age 21·4 years; n11, crossover design No effect on faecal mucin excretion
103 Oligofructose (20 g/d for 2 weeks) Men; Ca-restricted diet; mean age 27·7 years; n34,
crossover design
"Faecal mucin excretion
No effect on intestinal permeability
132 Inulin (1·5 g/l in formula) plus L. rhamonosus, zinc, iron and
soyabean polysaccharides
Indonesian infants with acute diarrhoea; aged 3–12
months; male; moderately dehydrated and
subsequently re-hydrated; n58 across two groups
#Duration of diarrhoea
96 Galacto-oligosaccharide/fructooligosaccharide mixture at 9:1
ratio (4 g/l in formula for 112 d) plus B. longum BL999
Infants; full-term newborns; not breast-fed after 14th
day of life; n42 in test group, n55 in control group
Non-significant trend for infants receiving the test formula
to have fewer respiratory tract infections
108 Inulin (5 g/d for 8 d) plus three other fibres, with or without
Pediacoccus pentoseceus,L. mesenteroides,L. paraca-
sei and L. plantarum
(Synbiotic2000)
Adults; patients undergoing duodenal surgery; n40
in fibre group; n40 in synbiotic group
In those receiving fibre plus probiotics, as opposed to those
receiving fibre alone, there was:
#Duration of antibiotic therapy
#Bacterial infections (wound, peritonitis, pneumonia)
No effect on length of hospital stay
91 Oligofructose (2g/d for 21 d) Infants; aged 7 19 months; n10 in prebiotic group;
n10 in control group
#Clostridial colonisation measured in faeces
#Diarrhoea episodes
#Vomiting
#Fever
#Number of infectious diseases requiring antibiotic
treatment
MBP, mechanical bowel preparation; MLN, mesenteric lymph nodes; NK, natural killer; ", increase/increased; #, decrease/decreased.
A. R. Lomax and P. C. Calder650
British Journal of Nutrition
Table 5. Effects of b2-1 fructans on inflammation in laboratory animal models
Reference
no. Prebiotic(s) used
Animal studied
(sex and age where given) Findings
25 Inulin (1 % w/v in drinking water, or oral
gavage 400 mg/d in tap water, or
rectal enema of 400 mg/d in sterile
saline)
Rats (male); colitis induced by dextran
sodium sulphate
#Mucosal damage with inulin in drinking water or by oral gavage
#Release of inflammatory mediators into colonic lumen (PGE
2
,
thromboxane B
2
, LTB
4
) with inulin in drinking water or by oral gavage
#Tissue myeloperoxidase activity with inulin in drinking water or by oral gavage
22, 116 Oligofructose (replacing 3 % w/w diet) Quails (2 weeks old); germ-free;
inoculated with different clostridial
species to induce neonatal necrotising
enterocolitis)
#Occurrence and severity of intestinal lesions, but the effects varied according
to the clostridial species used to induce neonatal necrotising enterocolitis:
With Clostridium perfringens þKlebsiella pneumoniae, oliogofructose completely
inhibited development of neonatal necrotising enterocolitis-like lesions
With C. perfringens þClostridium difficile, oligofructose significantly #severity
of disease
With C. perfringens þC. difficile þC. paraputrificum oligofructose
#occurrence of neonatal necrotising enterocolitis-like lesions
111 Fructo-oligosaccharides (1g/d) Rats (male); colitis induced by
trinitrobenzene sulphonic acid
#Gut mucosa inflammation shown by #myeloperoxidase activity and #macroscopic
damage
113 Oligofructose (6·3 % w/w diet) also
looked at resistant starch
Rats (male); colitis induced by dextran
sodium sulphate
At day 14, total macroscopic scores were #in the resistant starch supplemented rats
compared to both control and fructo-oligosaccharide treated rats
At days 7 and 14 histological scores in the caecum and distal colon were #in resist-
ant
starch treated rats compared to controls, but there was no significant effect of
fructo-oligosaccharides
No effect on histological scores in the proximal colon
114 Inulin (in a synbiotic: also containing
Lactobacillus acidophilus La5 and
Bifidobacterium lactis Bb12)
Rats (8 weeks old); colitis induced
(HLA-B27-B2-microglobulin transgenic)
After 2 weeks, colonic inflammation (measured histologically in the colonic tissues)
in the synbiotic group was #compared to controls
21 Oligofructose-enriched inulin (5 g/kg
body wt)
Rats (7 weeks old); specific pathogen
free; colitis induced (HLA-B27 transgenic)
#Development of colitis shown by #gross caecal scores, #inflammatory
histological scores in caecum and colon, and #inflammation of gut mucosa
#IL-1band "TGF-bin caecum; no effect on IL-10
#Interferon-gproduction from MLN cells; no effect on IL-10
117 Fructo-oligosaccharides (5 % w/w diet) Rats (male, 5 weeks old); with allergic
airway eosinophilia
No effect on allergic airway eosinophilia, with no differences in total cell,
eosinophil, lymphocyte or macrophage numbers in bronchoalveolar
lavage fluid, or on IL-4, IL-5 or interferon-gmRNA levels in lung tissue
26 Oligofructose-enriched inulin (1 g/d)
with/without B. infantis
Rats; colitis induced by dextran sodium
sulphate
#Disease activity index
#Colonic myeloperoxidase activity
#Colonic tissue IL-1b
#Bacterial translocation to MLN
No effect on:
Colonic TGF-bor IL-10
Detection of colonic TNF-a
133 Fructo-oligosaccharides (5 % w/w diet) Mice (male, 6 weeks old); pathogen-free
conditions; ovalbumin sensitised
#Number of mast cells in the duodenum
#Duodenal villus oedema formation rate
Non-significant #in number of CCR4
þ
cells in duodenal mucosa
No effect on:
Serum total IgE and ovalbumin-specific IgE
112 Fructo-oligosaccharides (1 ·15 g/ml twice
a day, administered at different stages
of colitis induction)
Mice (female, greater than 8 weeks old);
colitis induced by dextran sodium sul-
phate
#Disease activity index whether fructo-oligosaccharides given before and during,
during, or during and after colitis induction
#Damage to distal colon when fructo-oligosaccharides given before and during,
and during colitis induction, as shown by an increased colon length
"Crypt depth and crypt area in distal colon when fructo-oligosaccharides given during
colitis induction
Faster recovery from damage (shown by crypt area and crypt depth in
the distal colon) when fructo-oligosaccharides given during and after colitis induction
LTB
4,
leukotriene B
4
; MLN, mesenteric lymph nodes; TGF, transforming growth factor; ", increase/increased; #, decrease/decreased.
Prebiotics and immunity 651
British Journal of Nutrition
Thus, animal studies provide fairly strong evidence of a
protective effect of b2-1 fructans on colitis and necrotising
enterocolitis. The consistent findings may relate to the action
of prebiotics directly at the site of pathology. Effects of pre-
biotics on inflammatory processes distant from the intestinal
tract (e.g. the lung) may not be expected or may be much
smaller in magnitude.
Studies in man
Eleven studies of b2-1 fructans in human inflammatory
conditions were identified (four where synbiotics were used),
of which ten were conducted in adults (Table 6).
In accordance with findings from animal experiments, b2-1
fructans supplementation was shown to be beneficial in ulcera-
tive colitis patients. OF-enriched IN supplementation in such
patients decreased faecal calprotectin (a marker of intestinal
inflammation) and perception of abdominal pain, although
there was no change in the inflammatory mediators measured
(PGE
2
and IL-8) or on faecal excretion of human DNA
(a result of the mucosal inflammation seen in ulcerative
colitis)
(118)
. Although IN supplementation in patients with
ileal pouchanal anastomosis did not produce any effects on
clinical symptom scores, there were reductions in total
endoscopic scores, mucous exudates, total histological scores
and total Pouchitis Disease Activity Index
(119)
. A trial into
OF supplementation to patients with ileo-colonic Crohn’s dis-
ease reported positive results: disease activity scores were
reduced, and expression of toll-like receptor 4 on dendritic
cells in the lamina propria was increased, while there were
non-significant improvements in several other outcomes
(120)
.
Most trials in irritable bowel syndrome do not report ben-
eficial effects of b2-1 fructans on symptom scores
(121,122)
, per-
haps due to the nature of the disease regarding the relapse and
remission pattern, although there is one positive study in this
disorder
(123)
.
In contrast to the single animal study that reported no
benefit of FOS on allergic airway esoinophilia
(117)
, a study
in infants at risk from atopy found a reduction in the develop-
ment of atopic dermatitis in the group supplemented with FOS
in combination with GOS
(124)
. Several reasons could be given
to explain this inconsistency in results. In the human study, the
composition of this FOS GOS supplement was designed to
closely resemble the composition of oligosaccharides of the
mother’s milk, but as this was not the case in the animal
study it may be that the amount of prebiotic given was not
appropriate. Also, the rats were at a later stage of development
than the infants in the human study, and so as their immune
systems would have been more developed, the prebiotics
may have had less of an effect upon their immune system.
Finally, the infants were at risk from allergy because of par-
ental allergy (i.e. genetics was most likely an important
factor), while in the animal model, the allergy was induced
in the affected animals.
Synbiotic therapy for inflammatory bowel diseases produces
mixed results. OF-enriched IN in combination with Bifidobac-
terium longum improved markers of inflammation in patients
with active ulcerative colitis, such as decreases in TNF-a,
IL-1amRNA levels in mucosal tissue and decreased C-reac-
tive protein levels in the blood
(125)
. Mucosal tissue mRNA
levels of the b-defensins that are up-regulated in ulcerative
colitis were also reduced in this study
(125)
. IN given in
combination with other fermentable fibres and four lactic
acid bacteria had no effect on relapse rates (either endoscopic
or clinical) in Crohn’s disease patients undergoing resec-
tion
(126)
. In a study of patients with acute pancreatitis, a
synbiotic supplement was found to be more beneficial than
when the prebiotics were given alone regarding outcomes
such as systemic inflammatory response and multi-organ
failure
(127)
. Regarding irritable bowel syndrome, a formula
containing IN as well as Lactobacillius acidophilus,Lactoba-
cillius sporogenes (this bacterium is actually Bacillus sporo-
genes, a soil micro-organism claimed to have probiotic
properties) and Streptococcus thermophilius, amino acids
and vitamins resulted in significant reductions in abdominal
pain, distension and constipation
(123)
.
Conclusions
This paper has presented and evaluated results from all of the
studies available, to our knowledge, of the effects of b2-1
fructans upon immune function, the host’s ability to fight
infection, and inflammatory processes and conditions. The
results of these studies are often difficult to compare, due to
inconsistencies in methodology and the heterogeneity of the
subjects used. Despite this, much evidence suggests that
b2-1 fructans do influence some aspects of host immunity.
In laboratory animals, the innate and adaptive immune sys-
tems of both the GALT and the systemic immune system
have been shown to be modified by b2-1 fructans. In man,
most studies have investigated the effects of b2-1 fructans
upon the systemic immune system, with little effect observed
on innate immune function, but with many mixed results
reported regarding the adaptive immune system, suggesting
modification by b2-1 fructans on this aspect of immunity.
In animal models of infections, findings are conclusive regard-
ing the benefits of b2-1 fructans upon improving host resist-
ance. In man there is convincing evidence that b2-1 fructans
may reduce the incidence and duration of certain infections
in infants and children. b2-1 Fructan supplementation in
adults has not, generally, produced beneficial results, but
when given as a synbiotic to critically ill or surgical patients,
b2-1 fructans were shown to reduce infections. Taken together
these results suggest that b2-1 fructans, especially IN and OF,
may be most beneficial in those who are particularly suscep-
tible to modifications of their immune system. In animal
models of inflammation, b2-1 fructans have shown benefits
in models of colitis and necrotising entercolitis, perhaps due
to the pathological site of these conditions being the same
as the site of action of prebiotics. This theory is supported
by the observation of the lack of effect of b2-1 fructans
upon a model of allergic airway eosinophilia, an inflammatory
condition distant from the gut. However, in human infants, an
improvement in atopic dermatitis was observed in one study.
Inflammatory bowel conditions in human adults are improved
upon b2-1 fructan supplementation, but findings in irritable
bowel syndrome are mixed. It is important that future studies
build upon the findings of the studies reported here, in order
that a more complete picture of the effects of b2-1 fructans
upon immune function, infections and inflammation is
formed. The funding of these future studies needs to be con-
sidered carefully. The majority of studies conducted to date
A. R. Lomax and P. C. Calder652
British Journal of Nutrition
Table 6. Effects of b2-1 fructans on inflammation in human disease
Reference
no. Prebiotic used Subjects studied Findings
121 Oligofructose (6 g/d for 4 weeks) Patients with irritable bowel syndrome
patients; aged 18–65 years; n21;
cross-over design
No effect on:
Symptom scores
Whole gut transit time
122 Fructo-oligosaccharides (10 g/d for
2 weeks then 20 g/d for 10 weeks
Irritable bowel syndrome patients; mean age
45·1 years; n52 in test group; n46 in
placebo group
Improvements in symptoms were seen in both groups, but greater
improvement in placebo group
No significant differences between symptoms of irritable bowel syndrome at the
end of the study between the groups
119 Inulin (24 g/d for 3 weeks) Patients with ileal pouch –anal anastomosis;
mean age 37 years; n19; cross-over design
#Total histological and endoscopic scores, and #mucous exudates, resulting in
#Pouchitis Disease Activity Index
No effect on clinical symptoms
125 Oligofructose-enriched inulin (12 g/d for
4 weeks), plus Bifidobacterium longum
Patients with active ulcerative colitis;
age 24–67 years; n8 in test group, n8in
control
#Human bdefensin 2, 3 and 4 mRNA levels in mucosal tissue
#TNF-aand IL-1amRNA levels in mucosal tissue
#C-reactive protein levels in blood
No effect on IL-10 mRNA levels in mucosal tissue
120 Oligofructose and inulin (15 g/d for
3 weeks)
Ileocolonic Crohn’s disease patients;
age 29–56 years; n10; no placebo group
#Disease activity scores
"Percentage of CD11c
þ
dendritic cells expressing TLR-4 in
lamina propria
Non-significant "in percentage of CD11c
þ
dendritic cells expressing TLR-2
Non-significant "in percentage of IL-10 positive intestinal CD11c
þ
dendritic
cells from lamina propria mononuclear cells
No effect on:
Number of IL-6 positive intestinal CD11c
þ
dendritic cells
Number of IL-12 positive intestinal CD11c
þ
dendritic cells
123 Inulin plus Lactobacillus sporogenes,
L. acidophilus,Streptococcus thermophi-
lus, vitamins B
1
,B
2
,B
6
, vitamin PP,
vegetal charcoal, L. tryptophan and
angelica for 6 months
Irritable bowel syndrome patients; n37 in
treatment group, mean age 44·3 years;
n28 in control group, mean age 48·6 years
#Abdominal pain
#Abdominal distension
#Constipation
#Diarrhoea (non-significant)
#Alternating constipation/diarrhoea (non-significant)
124 Galacto-oligosaccharides and fructo-oligo-
saccharides (9:1 ratio, 0·8 g/100 ml,
for 6 months)
Infants at risk from atophy; bottle-fed; n102
in prebiotic group, n104 in placebo
#Development of atopic dermatitis
No effect on severity of dermatitis
118 Oligofructose-enriched inulin
(12 g/d for 2 weeks)
Ulcerative colitis patients with mild to moder-
ate disease; n9 in test group, mean age 37
years; n9 in placebo (maltodextrin), mean
age 36 years
#Faecal calprotectin (marker of intestinal inflammation, marker of the presence of
leucocytes) at day 7 in test group
#Dyspepsia-related health scores
#Disease activity (but so did placebo)
No effect on:
Faecal excretion of human DNA (a result of the mucosal inflammation in
ulcerative colitis, a marker of leucocyte and epithelial cell desquamation)
IL-8, PGE
2
or b-globulin gene (inflammatory mediators)
126 Inulin (2·5 g/d for 24 months)
Given in Synbiotic2000 (also contains
b-glucan, resistant starch and pectin and
Pediacoccus pentoseceus,
L. raffinolactis,L. paracasei subsp.
paracasei and L. plantarum)
Crohn’s disease patients undergoing
resection; n20 in test group, mean
age 36·1 years; n10 in control group,
mean age 34·7 years
No difference in relapse rates (endoscopic or clinical) between the groups
Prebiotics and immunity 653
British Journal of Nutrition
have been funded directly from industry or have involved
academic collaboration of some sort with industry. It is
not possible to identify whether studies funded by industry
yield different findings than those not funded by industry,
quite simply because there are so many of the former and so
few of the latter and also because the extent of industry sup-
port and funding for some published studies is not readily
apparent.
Acknowledgements
A. R. L. is supported by BENEO-Orafti (member of the
BENEO-Group). P. C. C. has research funding from
BENEO-Orafti.
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British Journal of Nutrition
... The induced modulation of the gut microbiota composition and activity is likely linked to health benefits in the gut and beyond. Several recent systematic reviews and meta-analysis have highlighted that via their specific modulation of the gut microbiota, inulin-type fructans can improve: bowel function by increasing the number of bowel movements (De Vries et al., 2019); glycaemic control as evaluated by fasting blood glucose or insulin, glycolysated hemoglobin (HbA1c) and homeostasis model assessment of insulin resistance (HOMA-IR) and more particularly in prediabetes and type 2 diabetes associated with obesity (Rao et al., 2019); regulation of blood lipids, for instance low-density lipoprotein cholesterol in all type of populations but also high-density lipoprotein in type 2 diabetes (Liu et al., 2016); immune function and again especially in those who are particularly susceptible to modifications of their immune response (Lomax and Calder, 2008). There is also increasing interest in supplementing diet early in life to support establishment of a well diverse and resilient gut microbiota when breastfeeding is not possible (Firmansyah et al., 2016). ...
... In fact, research in the field of molecular biology and clinical medicine has highlighted the effects of probiotics on lymphocytes and immunoglobulin production [12]. For example, flu and cold symptoms seem to decrease when substantial use of probiotics is implemented [13,14]. Furthermore, probiotics play a role in the prevention of allergic diseases, such as rhinitis [15], and infantile atopic eczema [16]. ...
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... The induced modulation of the gut microbiota composition and activity is likely linked to health benefits in the gut and beyond. Several recent systematic reviews and meta-analysis have highlighted that via their specific modulation of the gut microbiota, inulin-type fructans can improve: bowel function by increasing the number of bowel movements (De Vries et al., 2019); glycaemic control as evaluated by fasting blood glucose or insulin, glycolysated hemoglobin (HbA1c) and homeostasis model assessment of insulin resistance (HOMA-IR) and more particularly in prediabetes and type 2 diabetes associated with obesity (Rao et al., 2019); regulation of blood lipids, for instance low-density lipoprotein cholesterol in all type of populations but also high-density lipoprotein in type 2 diabetes (Liu et al., 2016); immune function and again especially in those who are particularly susceptible to modifications of their immune response (Lomax and Calder, 2008). There is also increasing interest in supplementing diet early in life to support establishment of a well diverse and resilient gut microbiota when breastfeeding is not possible (Firmansyah et al., 2016). ...
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... HMOs and other oligosaccharides can prevent the adhesion and infection of bacterial and viral pathogens by acting as soluble decoy receptors (36,145,242). Both HMOs and other prebiotics can also support intestinal barrier function via effects on the intestinal epithelium. ...
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... Nutrients like vitamins and minerals influence health and upregulation responses of the immune system to harmful agents as well as laboratory antigens (Jose et al. 2017;Pan et al. 2018;El-Senousey et al. 2018) . Prior to admission, COVID-19 patients should be checked for nutrient deficiencies using standard screening tools to determine effective treatment and dietary regimens (Reber et al. 2019;Lomax and Calder 2009;Yaqoob 2017). ...
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The immune system protects human health from the effects of pathogenic organisms; however, its activity is affected when individuals become infected. These activities require a series of molecules, substrates, and energy sources that are derived from diets. The consumed nutrients from diets help to enhance the immunity of infected individuals as it relates to COVID-19 patients. This study aims to review and highlight requirement and role of macro- and micronutrients of COVID-19 patients in enhancing their immune systems. Series of studies were found to have demonstrated the enhancing potentials of macronutrients (carbohydrates, proteins, and fats) and micronutrients (vitamins, copper, zinc, iron, calcium, magnesium, and selenium) in supporting the immune system’s fight against respiratory infections. Each of these nutrients performs a vital role as an antiviral defense in COVID-19 patients. Appropriate consumption or intake of dietary sources that yield these nutrients will help provide the daily requirement to support the immune system in its fight against pathogenic viruses such as COVID-19.
Chapter
The symbiotic association has been one of the most significant relationships of nature. Many microbes are symbiotically associated with humans specifically in the gut region. Both microbe and organism coevolve to endure any alteration in the environment. Deficits of normal microbiome enhance the probability of occurrence of dreadful diseases in the organism. Moreover, microbial dysbiosis and pathogenesis have attracted much attentions of researchers to develop new strategies, such as application of prebiotics and probiotics. Both of these are essential nutrient components that play a significant role in managing overall health conditions, as well as aid in maintaining a proper functional immune system in the host. In this current chapter, we discuss the numerous features of prebiotics and probiotics along with their history of development and their role in combating some common but dangerous diseases. We have also given emphasis on their impact and their immune‐modulatory mechanism, as well as their contribution in ameliorating immune‐related diseases. This chapter aims to draw the attention of investigators involved in various fields of the health sector for the development of vaccines, pharmaceutical components, and drugs.
Chapter
Numerous functional products of significant health benefits beyond the basic nutritional functions have been developed in the past few decades from high fibre ingredients, comprising of fruits and vegetables, unrefined or whole grains, legumes, and nuts. Eating of these products are linked to the prevention of diverse life-threatening health challenges, like: non-insulin dependent diabetes, coronary heart disease and few cancers. High dietary fibres functional products which are made up of different types of fibre, tend to be more filling, thus resulting in eating less and increased satiety due to the characteristics of the various inherent dietary fibres. Dietary fibres are plant polymer matrix grouped according to their characteristics solubility, viscosity, and fermentability, resulting into soluble dietary fibres (SDF) and insoluble dietary fibres (IDF). Dietary fibres are of varied physicochemical properties like; being responsible for bacterial fermentation, water-holding capacity, cation-exchange, and adsorptive functions; all the aforementioned influences the homeostatic and therapeutic functions of high fibres functional products in nutrition and consequently consumers’ acceptability. The challenge with the formulation of high fibres functional products is in meeting the nutraceutical and technological requirements. This review projects the characteristics, types and formulation, the relationship between the techno-functional and physiological properties of high fibres functional products.KeywordsHigh fibreFunctional foodsTechno – functional propertiesPhysiological properties
Chapter
The mucosal lining of the gastrointestinal tract, respiratory tract and urogenital tract exhibits immunological properties like ciliary projection, production of cytokines, and secretion of antibodies. In recent years, mucosal immunity is being explored as one of the most important strategies for disease prevention. Prebiotics on the other hand are a class of nutrients that are mostly consumed by the host’s local microbiome. Role of prebiotics on overall health of animal has sparked curiosity of scientific communities. Prebiotics are metabolized by the resident microbiome, which results in the production of biologically essential compounds such as short-chain fatty acids (SCFAs) and various other metabolites, such as fructo-oligosaccharides and galacto-oligosaccharides. Prebiotics and their by products can act as good immunomodulators. But the problem with prebiotics is that they are generally present in a very minuscule amount in our daily diets, which is generally insufficient to produce biologically significant amount of beneficial end-products via bacterial metabolism. Exogenous administration of prebiotics not only improved the microbiome but also the overall immune status of experimental models. The importance of mucosa in the immune system and the properties of prebiotics in modulating the immune health together can be harnessed to provide a beneficial approach for disease management. Hence, prebiotics may possibly be one of the most viable alternatives to minimize the widespread use of antibiotics for infections related to not only respiratory mucosa but also other important mucosal sites like the gastrointestinal system.
Thesis
In this thesis, we aimed to evaluate the immunomodulatory effects of (selected) bovine milk components (and metabolites induced by them) on the immune function of humans. Chapter 1 gives an introduction to the topic and provides an outline of fundamental aspects of the immune system that are referred to in later chapters. In Chapter 2 , we summarized and addressed the primary components of bovine milk that have the potential to induce epigenetic changes to exert their immune-supportive effects during childhood. We reviewed the proposed mechanisms, including innate immune training that induces epigenetic modification. Through these mechanisms, the components may exert an effect on the immune system with implications for allergies and asthma. Living in a farm environment and raw bovine milk bioactive components were addressed as contributing factors that may reduce allergies in infancy and beyond. HMOs and bovine milk oligosaccharides (mainly 3'-Sialyllactose) serve as substrates for the SCFA-producing microbiota. SCFAs are potent immune modulators and have significant roles in maintaining homeostasis and steering the response of the immune cells to the environment. In Chapter 3 , we showed that butyrate and propionate had inhibitory effects on the activation of myeloid cells and lymphocytes, whereas acetate had a more selective impact on the immune cells. Production of inflammatory cytokines was suppressed in monocytes, mDCs, and pDCs, as well as T lymphocytes. SCFAs could not train the monocytes for enhanced response to secondary TLR stimulation in vitro but instead induced a tolerance-like phenotype. We attempted to explain the observed effects according to the differential expression of relevant SCFA receptors and transporters. Bovine milk IgG (bIgG) binds to human pathogens such as RSV and, via the Fc portion, interacts with the FcγRs on human immune cells. The relevance of bIgG-containing immune complexes (ICs) on activation of CD32 was studied in Chapter 4 , where we could establish a method to show the direct binding of bIgG ICs to immune cells. It was demonstrated that ICs containing bIgG are directly bound to human CD14+. Subsequently, we could show the role of bIgG ICs on induction of trained immunity after binding to monocytes while contrary to previous reports, (monomeric) bIgG alone did not have similar effects suggestive of the presence of other contributing factors. Human infection challenge models are used as an alternative to field trials to study the immune-supportive effects of dietary components. In Chapter 5 , we found that ingestion of a dairy product (WPC) in a human challenge model did not influence the responsiveness of myeloid cells from healthy volunteers to ex vivo stimulation with TLR ligands. It also did not change the gene expression pattern of the PBMCs isolated from the same donors. Although the model was utilized successfully before, the study product did not exert beneficial effects. We speculated that the study population might be a critical factor for no apparent impact. In Chapter 6 , we focused on optimizing an E. coli infection challenge model in humans to study the protective effects of dietary components and the correlates of protection at rechallenge. Primary infection with even low doses (1E6 CFU) of E. coli protected the subjects against reinfection with a high dose (1E10 CFU) of the same pathogen. Following the primary infection, serum anti-CFAII IgG levels were raised, and monocytes and mDCs responded more strongly to ex vivo stimulation. The latter may indicate the occurrence of trained immunity in vivo. Throughout Chapter 7 , we reviewed and discussed the most important findings of our research and placed the findings in a broader context by relating them to the most recent published literature. In addition, we identified subjects for future study perspectives to follow the work done in this project. Immunomodulation by nutrition or supplementation of the food with potent immunomodulatory components can provide immune support for the immune system in individuals with an immature or impaired immune system. To substantiate the dietary components' beneficial effects and define the supporting mechanisms involved, we studied bovine IgG and metabolites induced by milk oligosaccharides to substantiate their health-promoting and immune-mediated effects.
Article
Purpose: The Multi-echo Dixon (ME-Dixon) is a non-invasive quantitative MRI technique to diagnose non-alcoholic fatty liver disease (NAFLD). In this study, the hydrogen proton MR spectroscopy (1H-MRS) was used as a reference to explore the accuracy of the ME-Dixon technique in evaluating hepatic steatosis in NAFLD patients after ingesting formulated food and its correlation with changes in clinical indicators. Methods: Twenty-seven patients with NAFLD were enrolled. Fifteen patients completed 12 weeks of treatment with prebiotics and dietary fiber. In addition, abdominal MRI scans and blood tests were performed before and after treatment. The MRI-proton density fat fraction (MRI-PDFF) and MRS-PDFF were measured using the ME-Dixon and 1H-MRS techniques. The Bland-Altman method and Pearson correlation analysis were used to test the consistency of the two techniques for measuring the liver fat content and the changed values. Besides, correlation analysis was conducted between the MRI-PDFF value and metabolic indicators. Results: In the PDFF quantification of 42 person-times and the monitoring of the PDFF change in 15 patients under treatment, there was a good consistency and a correlation between MRI and MRS. At baseline, MRI-PDFF was positively correlated with insulin resistance index (HOMA-IR), fatty liver index (FLI), and liver enzymes. After treatment, the changes in MRI-PDFF were positively correlated with the recovery degree of FLI and liver enzymes. Conclusion: ME-Dixon has a good consistency and a correlation with MRS in quantifying the liver fat content and monitoring the treatment effect, which may be used as an accurate indicator for clinical monitoring of changes in the liver fat content.
Article
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Ninety-eight women-infant pairs were followed for up to 50 weeks in the northern part of Guadalajara, Mexico, from August 1986 to July 1987 as part of a community-based, prospective study of the relation between infant feeding patterns and enterotoxigenic Escherichia coli producing heat-labile toxin (LT-ETEC) diarrheal disease. Strictly formula-fed children had an incidence of diarrhea over three times that of strictly breast-fed infants and twice that of breast-fed and supplementally fed children. Strictly formula-fed infants colonized by LT-ETEC were symptomatic for diarrhea nearly three times as often as strictly breast-fed infants and twice as often as infants receiving a mixed diet. The fitting of parametric hazard models to durations until LT-ETEC colonization revealed that the hazard for the first colonization was time invariant. The hazard of diarrhea increased by 400-500% during the rainy season or among children 3 months of age or older who received avena, a barley drink. The best-fitting hazard models to durations until symptomatic expression of LT-ETEC infection all increased through time. This hazard was inversely impacted by the overall amount of LT-ETEC-specific, immunoglobulin A antibodies the infant received via the mother's breast milk and by the provision of traditional medicinal teas.
Article
Irritable bowel syndrome (IBS) is the most common functional gastrointestinal (GI) disorder seen in primary care and gastroenterology practice. It was described as long ago as 1849 by W Cummings who wrote in the London Medical Gazette, 'The bowels are at one time constipated, at another lax, in the same person... How the disease has two such different symptoms I do not profess to explain...'.