27
Understanding prebiotics and scientific discoveries furthering their development Karen P. Scott Microbiology Group Rowett Institute of Nutrition and Health

Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Embed Size (px)

Citation preview

Page 1: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Understanding prebiotics and scientific discoveries furthering

their development Karen P. Scott

Microbiology Group

Rowett Institute of Nutrition and Health

Page 2: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

What are synbiotics, prebiotics, probiotics The gut microbiota Can we use prebiotics to improve health? Are Prebiotics the most effective approach to improving health?

CONTENT

Page 3: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Definitions

• Probiotics

live microorganisms which, when administered in adequate amounts confer a health benefit on the host (FAO/WHO 2001)

• Prebiotics

A selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health. (Gibson et al. 2010)

Synbiotics

mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract (Andersson et al 2001)

Page 4: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Definitions

• Probiotics

Consumption of live bacteria

• Prebiotics

Food for bacteria that are already in large intestine

Synbiotics

mixtures of live bacteria and substrate that can help them (and resident bacteria) grow and survive

Page 5: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Prebiotics

A selectively fermented

ingredient

that results in specific

changes in the composition

and/or

activity of the

gastrointestinal microbiota,

thus conferring benefit(s)

upon host health.

Must reach the large intestine

undigested by host enzymes

Must only be fermented by

one/few colonic

bacteria, not by all bacteria

OR

Must change the balance of

fermentation products

Must be a ‘measurable’

health benefit

Definition Description Example

Fructooligosaccharides

(FOS)

Increases numbers

of Bifidobacteria

Increases butyrate

production

Eg increases Ca

absorption

Page 6: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Prebiotics

Accepted examples of prebiotics

Fructo-oligosaccharides (FOS)

Galacto-oligosaccharides (GOS)

Inulin

Candidate prebiotics

Lactulose

Human milk oligosaccharides

(HMOs)

Arabinoxylan

Resistant starch

Occurrence

FOS/inulin occur naturally in some foods

Chicory, garlic, artichoke, leek

Increase amounts by supplementation

cereals, bread, yoghurts,etc

Use in infant formula/foods

(FOS and GOS)

Target (adult) intake: 2 – 20g/day

Health benefits

Change bacterial growth/activity

Stool bulk/transit time

BUT current lack of real biomarker for

GI health

Garlic (9-16%) Leeks

(3-10%)

Onion (2-6%)

Page 7: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

What are synbiotics, prebiotics, probiotics The gut microbiota Can we use prebiotics to improve health? Are Prebiotics the most effective approach to improving health?

CONTENT

Page 8: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Human Gut Microbiota

Colon

1010 - 1012/ ml gut contents (large intestine)

Outnumber human cells in the body by 10 : 1

Complex and diverse bacterial community

>500 hundred different bacterial species colonise each individual

Most are highly oxygen sensitive, but can be cultured

Molecular approaches (mainly based on 16S ribosomal genes) allow analysis of bacterial communities without cultivation

Until recently >70 % of ‘phylotypes’ belonged to no known cultured species

Page 9: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Faecalibacterium prausnitzii

Eubacterium rectale

Colinsella aerofaciens

Clostridium clostridioforme

Bacteroides vulgatus

Anaerostipes hadrus

Ruminococcus bromii

Eubacterium hallii

Blautia wexleri

Bacteroides dorei

Roseburia faecis

Dorea longicatena

Subdoligranulum variabile

Bacteroides uniformis

Ruminococcus obeum

Bacteroides ovatus

Blautia luti

Parabacteroides distasonis

sp nov A2-166

sp nov SR1/5

Lachnospira pectinoschiza

sp nov 80/3

Dialister invisus

Roseburia inulinivorans

Ruminococcus callidus

othersData from 6 healthy, obese individuals; converted from Walker et al 2011, ISME J

Dominant bacterial phylotypes

~50% of sequences correspond to 25 most abundant species We have cultured representatives of all of them

XIVa, E.rectale/Roseburia group

Bacteroidetes

IV, Ruminococcus group

295 additional

phylotypes

8% 5%

2%

0.6%

IV, F.prausnitzii group

major

butyrate

producers

Major propionate

producers

Major lactate

utilisers

(into butyrate)

Top 25 range of products

Page 10: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Food

Small intestine* large intestine

Digestion of dietary carbohydrate,

starches, sugars, fat, protein

Resistant Starch, Fibre (NSP), prebiotics

SCFA, gases, phytochemicals,

other metabolites, minerals

Blood stream

faeces

Monosaccharides, fat, aminoacids,

soluble phytochemicals

absorption

Undigested carbohydrate, Lignin, unabsorbed nutrients

Proximal Distal

SCFA concentration gradient (acetate, butyrate, propionate)

[Adapted from Topping & Clifton, 2001 Physiol Rev. 81; 1031-1064]

Fate of dietary products in the GIT

Transported in blood to

peripheral tissues,

used in lipogenesis

Important for

gluconeogenesis

in the liver;

satiety signalling

Major energy source

for human colonocytes;

Protects against cancer

Page 11: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Disease Microbial association Therapy target

or substrate

Scientific evidence

IBS Altered diversity

(inc Clostridium;

Dec Bifido, Fprau)

Inc or dec fibre

intake

(eg inc starch)

variable

IBD Reduced diversity (inc proteo/enterobacteria;

dec Lachnospiraceae,

cluster IV)

Colorectal cancer Inc Fusobacterium, E.

coli

dietary fibre

prebiotics

Alter fermentation, faecal

bulking, reduced transit time

Coronary heart

disease

Lower serum

cholesterol;

Inc β-glucan

Reduce cholesterol, BP

Obesity Reduced diversity Appetite regulation ?

Diabetes Inc opportunist pathogens,

dec butyrate producers prebiotics Modify glycemic and insulin

response

Osteoporosis Inc colonic pH Prebiotics Lower pH, increase Ca

absorption

Diseases where dysbiosis of the gut microbiota has

been noted (and opportunities for prebiotics)

Page 12: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

The microbial community and disease : IBS

Irritable bowel syndrome (IBS) – complex disease, different manifestations

Increased fibre intake helps some sufferers, increases symptoms in others

more variability between IBS-C individuals than between healthy volunteers.

PCA of FISH data for background samples Significantly less Roseburia and Bifidobacteria species in IBS:healthy

Chassard et al Aliment Pharm Ther. 2012, 35; 828-838

7.5

8

8.5

9

9.5

10

10.5

0.5 1 1.5 2 2.5 3 3.5

1=Back; 2=Dextrose; 3=Starch

log

Rre

c

5

5.5

6

6.5

7

7.5

8

8.5

9

9.5

10

0.5 1 1.5 2 2.5 3 3.5

1=Back; 2=Dextrose; 3=Starch

log

Bif

E.rectale/Roseburia group p=0.006

Blue – healthy Red – IBS

Bifidobacteria p=0.029

baseline dextrose starch

baseline dextrose starch

Page 13: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

What are synbiotics, prebiotics, probiotics The gut microbiota Can we use prebiotics to improve health? Are Prebiotics the most effective approach to improving health?

CONTENT

Page 14: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Health benefits attributed to prebiotics

Improved gut function

stool bulking and faster gut transit

Management of Inflammatory bowel disease

reduction in inflammatory markers

Prebiotics may reduce the risk of colon cancer

reduced DNA damage and cell proliferation, faster gut transit

Prebiotic (GOS/FOS) supplementation of infant formula increases

bifidobacteria numbers

Prebiotics (FOS/Inulin) increase calcium absorption and bone health

pH effect

Consumption of prebiotics instead of sugars can lower glycaemic index induce a lower blood glucose rise after meals compared to those containing sugars

Rodent studies indicate that prebiotics reduce food intake and fat mass

SCFA stimulated secretion of gut peptides

(PYY, GLP-1, reduced ghrelin) more work required

?

Jan 2014 – EFSA preliminary approval of health claim

Inulin/FOS can lower glycaemic index

“consumption of foods containing non-digestible carbohydrates instead of

sugars induces a lower blood glucose rise after meals compared to those

containing sugars”

Jan 2014 – EFSA preliminary approval of health claim

Increased consumption of Native chicory inulin can

increase stool frequency

Page 15: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Galacto-oligosaccharides (GOS)

GOS are produced from lactose

Gal Glu Gal Glu Gal Glu n

Glu

β-galactosidase

Lactose Lactose Galacto-

Oligosaccharides (n = 1 – 7)

Glucose

GOS stimulate growth of Bifidobacteria

9 studies in healthy adults between 1990 – 2004

2 studies also showed increase in Lactobacilli

8 studies in infants comparing GOS formula with normal formula

2 studies also showed increase in Lactobacilli

Applications – improve infant formula to be more representative of breast milk

- use to improve constipation and increase Bifidobacteria

populations in geriatrics

Page 16: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

More recent studies using GOS prebiotic

supplementation

Prevents decrease in bifidobacteria population and butyrate production

otherwise shown following amoxicillin treatment

Ladirat SE et al BJN 2014

Reduced colic incidence in formula fed infants, increased bifidobacteria

(mimics effect of human milk)

Giovannini et al J Am Coll Nut 2014

Increases Ca absorption and bifidobacteria counts in adolescent girls

Whisner et al 2013 BJN

Increases bifidobacteria in healthy adults – but response is individual-specific

Responders and non-responders

Davis LMG 2011 PLosOne

- Bacterial effects mainly focus on Bifidobacteria

Page 17: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Dietary supplementation with ‘traditional’ prebiotics

Many studies have shown that fructo-oligosaccharides (FOS) and inulin

stimulate numbers of Bifidobacteria = Bifidogenic

BUT Bifidobacteria produce lactate, and prebiotics stimulate butyrate

production

HOW?

2 possible mechanisms

1. additional direct stimulation

of butyrate butyrate producers

2. Bacterial cross-feeding

Fructans, β(1-2) fructose polymer

FOS n= 2-8 (DP)

inulin 9<n<60

Page 18: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

0

10

20

30

40

50

Bact Cl XIVa Rrec2 Rrec1 Ehal Cl IV Fprau Rum CoAT Bifids

% o

f u

niv

ers

al 1

6S

rR

NA

ge

ne

co

pie

s

background

control

inulin

Effect of prebiotics (inulin) on the faecal microbiota

Cluster XIVa Cluster IV

P = 0.005

P = 0.027

Q-PCR quantification of dominant groups of the human gut microbiota

Stimulation of bifidobacteria and Faecalibacterium prausnitzii –

produces butyrate Fuller et al, BJN (2007); Ramirez et al, BJN (2009)

Page 19: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Commensal anaerobes use prebiotic substrates for growth

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

YCFA basal

Starch

P95 FOS

Synergy

HP

Dahlia inulin

XOS

0

0.2

0.4

0.6

0.8

1

1.2

Bi. infantis E. rectale R.inulinivorans

R. faecis

P95 FOS

synergy

HP

dahlia

As complexity of substrate

No. of bacteria utilising it

Structure of prebiotic important

Scott KP et al FEMS Micro Ecol 2014

Page 20: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Starch/FOS

Acetate L-Lactate Formate

Eubacterium

hallii

Bacterial cross-feeding

Acetate

Lactate

Formate

Butyrate

0

2

4

6

8

10

12

18

20

Bif. adol.

E. hallii

16

14

SC

FA

co

nce

ntr

ati

on

[m

M]

Duncan SH et al, AEM, 2004

Bifidobacterium

adolescentis

Gut bacteria exist in a complex mixed ecosystem

Page 21: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Starch/FOS

Acetate L-Lactate Formate

Eubacterium

hallii

Butyrate

cross-feeding

Acetate

Lactate

Formate

Butyrate

0

2

4

6

8

10

12

18

20

Bif. adol. Bif. adol.

E. hallii E. hallii

16

14

SC

FA

co

nce

ntr

ati

on

[m

M]

(Duncan et al, AEM, 2004;

Belenguer et al, AEM 2006)

Bifidobacterium

adolescentis

Bacterial cross-feeding

Gut bacteria exist in a complex mixed ecosystem

Duncan SH et al, AEM, 2004

Belenguer et al, AEM 2006

Page 22: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Increase in Bifidobacteria

(Resistant starch) FOS INULIN

Direct utilisation by butyrate producers

[Butyrate]

Mechanisms by which prebiotics increase butyrate

production?

[Lactate] [Acetate]

Utilisation of intermediate

products: CROSS-FEEDING

Prebiotics and butyrate – 2 routes for production

Page 23: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Synbiotic = probiotic plus prebiotic

Combination critical - Probiotic bacterium should be able to use prebiotic as

a growth substrate – can help survival and establishment

Is a prebiotic best given along with a probiotic bacterium

- as a synbiotic?

Lactitol and Lb. acidophilus in elderly Increase in Lb. acidophilus and total Bifidobacteria

synergy 1(FOS) plus B. animalis Increased population of total bifidobacteria,

Mix of 4 bacteria plus FOS reduced upper GIT infection in intensive care patients

Different mix of 4 bacteria with 4 prebiotics –reduced post-operative infections following liver transplants (3%

compared to 48%)

Synbiotic therapy (GOS + B. breve + Lb. casei) significantly improved numbers of beneficial bacteria (Bifids

and Lactobacilli), and decreased the number of harmful bacteria in elderly patients undergoing

gastroenterological surgery

Synbiotic consumption (B. longum plus Synergy1) improved clinical symptoms in Crohns disease patients

Distinguishing responders : non-responders is an important factor for

consideration in all prebiotic/probiotic/synbiotic studies

Page 24: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Volunteers with the lowest initial levels of bifidobacteria gave the

maximum increase in bifidobacteria numbers after inulin

supplementation

Ch

an

ge

in

bifid

ob

acte

ria

(lo

g1

0 c

ells

/g fa

ece

s)

aft

er

tre

atm

ent

Bifidobacteria (log10 cells/g faeces)

at start of study

Prebiotic effect of fruit and vegetable shots containing Jerusalem artichoke

inulin: a human intervention study P. Ramnani, et al BJN (2010), 104, 233–240

Background levels of host bacteria critical in level of response

Greatest change in

Bifidobacteria numbers in

individuals with lowest starting

populations

Page 25: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Increasing carbohydrate content of diet has a prebiotic effect –

Increases numbers of Roseburia group and stimulates

butyrate production

- is this selective fermentation ?

Increasing RS III component of diet has a prebiotic effect –

selective fermentation, increasing numbers of

R. bromii and E. rectale

- what is benefit on host health ?

What makes a prebiotic? – not always easy to answer

Prebiotics

A selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health. (Gibson et al. 2010)

Identifying new prebiotics

Page 26: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Is there a role for new prebiotics to specifically modify the composition of the gut microbiota and improve health?

Targeted approach :

Microbiome studies identify bacteria lacking in disease states Genomic studies identify substrate degradation capabilities In vitro testing to confirm bacterial growth on novel ‘prebiotic’ In vitro testing to confirm increased population In vivo confirmation – microbiota composition and health markers

Ultimate requirement: Personalised nutrition based on individual microbial profile

Prebiotics can help boost the numbers of key species

ALREADY THERE

Novel prebiotics

Page 27: Understanding prebiotics and scientific discoveries ...d3hip0cp28w2tg.cloudfront.net/uploads/2015-11/dr-karen-scott-1.pdf · Understanding prebiotics and scientific discoveries furthering

Acknowledgements

Jenny Martin Sylvia Duncan Petra Louis Alan Walker Professor Harry Flint Everyone in the microbial ecology group - including numerous visitors and summer students Everyone in the Human Nutrition Unit Genomics section (Gill Campbell, Pauline Young) BioSS (Claus-Dieter Mayer, Grietje Holtrop)

Annick Bernalier-Donadille, Christophe Chassard