The Effects of Inulin on Gut Health and Bifidobacterial Populations in the Colon
diet also had reduced concentrations of salmonella in intestinal contents and tissues; this difference was significant (p<0.05) in Peyer’s patches.27
Inulin-type prebiotics with higher DPs may offer potential advantages over smaller molecules; notably, their bifidogenic effect is more prolonged, and hence extends further along the colon.36
Table 2: Effect of Dietary Supplementation with Prebiotic (15g/day Inulin Plus Oligofructose) on Microbiota Populations on Colonic Mucosa
Bacterial Types Inulin (DP 3–60)
has shown more pronounced prebiotic effects and slower fermentation than oligofructose (DP 2–20) in the SHIME.35
These higher bifidogenic
effects of inulin compared with oligofructose were most marked in distal colon compartments, and the effect continued after the addition of inulin stopped.35
Both inulin and oligofructose increased short-chain fatty acid production and lactic acid bacteria in both the proximal and in the distal colon compartments of the SHIME, but inulin was fermented more slowly; however, inulin decreased the numbers of opportunistic pathogen species in the descending colon whereas oligofructose did not. Oligofructose also increased ammonium concentrations in the descending colon and this is associated with negative health effects, particularly proteolysis leading to tumorigenesis. In another study, an in vitro comparison of oligofructose versus a high-solubility inulin preparation showed that inulin was fermented more slowly than oligofructose.36
Health Benefits of Inulin-type Fructans As with other types of dietary fiber, inulins generally reduce gut transit times and increase stool mass.37–40
However, the prebiotic effects of
inulins offer a further range of potentially valuable health benefits, and some examples are outlined below.
Inflammatory Bowel Disease
Disruption of the mucosal biofilm has been implicated in the pathogenesis of inflammatory bowel disease (IBD), and biopsies of inflamed mucosa have revealed reduced bifidobacterial populations in adolescents with ulcerative colitis (UC) or Crohn’s disease.41,42
The mucus layer of biopsy
samples taken from inflamed areas was thinner than either healthy controls or non-inflamed sites in IBD patients, which is consistent with the model illustrated in Figure 4.41
Inulin and other prebiotic carbohydrates have shown promise for the management of IBD.43 Cancer
Oligofructose-enriched inulin combined with the probiotic Lactobacillus plantarum, may reduce the risk of colon carcinogenesis according to experimental results in a rat model.44
A diet containing about 2% oligofructose-enriched In vitro and animal model studies
showed that B. longum reduced hypercholesterolemia and increased concentrations of lactic acid bacteria thereby reducing the risk of colon cancer.45
inulin increased tumor necrosis factor-alpha (TNF-α) levels (p<0.001) and reduced bacterial enzyme activity (p<0.001) and fecal bile acid concentration (p<0.01).45
In the SHIME, chicory inulin also has
shown a potentially protective effect against carcinogenesis producing a significant decrease in bacterial production of the genotoxic metabolite 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP).46
Cardiovascular Risk
There is an established link between inulin and other dietary fibers and improved serum lipid profiles.47
Accumulating data suggest that such
improvements may be mediated by alterations to gut microflora.48,49 B. longum can reduce low-density lipoprotein (LDL) concentrations and
US GASTROENTEROLOGY & HEPATOLOGY REVIEW Commensal bacteria Source: Kleessen et al., 2005.27
also may increase high-density lipoprotein (HDL) concentrations according to in vitro and animal studies.45
Pathogenic bacteria
Total aerobes Coliforms
Total anaerobes Bacteroides Bifidobacteria Eubacteria Lactobacilli Clostridia
p=0.04.
Proximal Colon Control 6.4 (0.4) 6.2 (0.4) 8.5 (0.2) 8.1 (0.3) 5.3 (0.4) 4.5 (0.3) 3.0 (0.1) 5.1 (0.3)
Distal Colon
+Prebiotic Control 5.9 (0.4) 5.6 (0.4) 8.6 (0.2) 8.3 (0.2) 6.3 (0.3)* 6.0 (0.4)‡ 3.7 (0.2) 4.9 (0.3)
p=0.059; †
6.4 (0.3) 6.2 (0.3) 8.7 (0.1) 8.3 (0.2) 5.2 (0.3) 4.6 (0.3) 3.1 (0.1) 5.0 (0.3)
p=0.01; ‡
+Prebiotic 5.9 (0.4) 5.7 (0.4) 8.6 (0.1) 8.5 (0.2) 6.4 (0.3)† 6.1 (0.3)§ 3.6 (0.2)** 4.9 (0.3)
Values are expressed as mean (standard error of mean) in log colony-forming unit/g mucosa. Significance of difference, control versus prebiotic: * p=0.017; **
p=0.003; § Source: Langlands et al., 2004.16
Figure 4: Illustration of an Intact Mucosal Barrier, Maintained by Adherent Biofilms of Commensal Bacteria, and the Disruption that can Occur if these Biofilms are not Maintained
Intact mucosal barrier Lumen
Mucus Apical
membrane
Epithelial cell
Nucleus
Basolateral membrane
Disturbed mucosal barrier p=0.002,
Supplementary dietary inulin in
enriched pasta also has been linked with significantly reduced LDL and increased HDL concentrations in humans that provide potential cardiovascular health benefits.50
Infant and Child Nutrition
Early bacterial colonization of the infant gut and establishment of stable microbiota communities may have major implications for long-term health, and human milk contains prebiotics (human milk oligosaccharides [HMOs]) that promote bifidobacterial proliferation. Infant formula manufacturers are adding inulin and other oligosaccharides to products in an attempt to mimic the health benefits of HMOs, and studies have shown significant short-term benefits.32
However, adverse effects such as
diarrhea, eczema, and irritability have also been reported and potential intolerance may be a concern. The stool characteristics of babies born
61
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100