ASN/AAFP webinar series: Putting Nutrition Science to Work in Family Medicine
Nutrition and Digestive Health
Topic
1. Help patients
make small,
evidencebased dietary
changes to
promote
digestive
health
Key Points
Definition of Digestive Health from
American Gastroenterological Association:
Ability to process nutrients through properly
functioning gastrointestinal organs, including
the stomach, intestines, liver, pancreas,
esophagus and gallbladder, Most people who
are in good digestive health are of
appropriate weight and don’t regularly
experience symptoms like heartburn, gas,
constipations, diarrhea, nausea or stomach
pain.
In addition:
GI tract is first line of defense against
invading pathogens and 70% of immune cells
are associated with the gut.
To get good digestive health:
 Achieve and maintain appropriate
weight
 Eat a balanced and varied diet
 Reduce stress
 Be physically active
Other tips:
 Stay hydrated; include beverages
with meals or snacks.
 Eat mindfully, how you eat is just as
important as what, eat slowly,
 Avoid bloating by introducing fiber
slowly into the diet.
Incorporating fiber and probiotics in the diet
to help keep healthy people healthy.
For Fiber:
Primary recommendation is to follow the
Dietary Guidelines and MyPyramid to
incorporate adequate fruits, vegetables,
whole grains and legumes as part of the diet
to get the recommended fiber. Following
MyPyramid eating plan would bring majority
of North American adult population close to
recommended range of 14g /1000 cals.
Additionally, a higher fiber diet will likely
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Resources/References
Position of the American Dietetic
Association: Health Implications of
Dietary Fiber J Am Diet Assoc
2008;108:1716-1731.
translate to a less calorically dense diet,
therefore, impacting weight management.
However, most Americans get only ½ the
recommended 25 grams of fiber per day.
Looking for foods with added fibers is an
important way to get fiber benefits.
For Probiotics: Look for products that
indicate what strain of bacteria is provided.
Look for products with strains that have
proven science for a digestive health benefit,
such as improved transit time.
2. Role of
Nutrition in
trt/prevention
of GERD & IBS
Role of fiber (prebiotics) and probiotics in IBS:
Probiotics may be efficacious for use in IBS,
but still more work to be done to understand
the best strain and magnitude of benefit.
Composition of colonic microbiota affects the
fermentation of carbohydrates which impacts
motility. Dietary fiber may improve
symptoms of patients with IBD.
Clinical Endpoints Using Probiotics
and Prebiotics for IBD, IBS, and
Infectious Diarrhea
Fergus Shanahan, MD (May 27th)
http://www.gastro.org/educationmeetings/onlineeducation/probiotics-andprebiotics-webinar-series
Bijkerk CJ et al Systematic review:
the role of different types of fibre
in the treatment of irritable bowel
syndrome. Aliment Pharmacol
Ther. 2004;19:245-251.
Position of the American Dietetic
Association: Health Implications of
Dietary Fiber. J Am Diet Assoc
2008;108:1716-1731.
3. Types of fiber
and how to
introduce into
a healthy diet
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Why:
Populations who consume more dietary fiber
have less chronic disease. The intake of
dietary fiber has beneficial effects on risk
factors for developing several chronic
diseases such as diabetes and heart disease,
and also plays a role in weight management.
Evidence regarding the relationship of fiber
and cancer needs further research.
Moayyedi P et al. The efficacy of
probiotics in the treatment of
irritable bowel syndrome: a
systematic review. Gut
2010;59:325-332
Position of the American Dietetic
Association: Health Implications of
Dietary Fiber. J Am Diet Assoc
2008;108:1716-1731.
Cummings JH. Spiller GA ed CRC
Handbok of Dietary Fiber in
Human nUtirtion. 2nd ed. Boca
Taton, FL CRC Press: 1993:263-
Adequate fiber from foods may: ameliorate
constipation & diverticular disease, provide
fuel for colon cells, reduce blood glucose and
lipid levels, provide source of nutrient-rich,
low-energy –dense foods that could
contribute to satiety.
Oat bran, barley bran, pysllium have heart
health claims related to ability to lower LDLC.
Wheat bran commonly linked to laxation
effect.
How much:
14 g/1000kcal or roughly AT LEAST 25 g/day.
Most Americans getting only 15 g/day.
Need all kinds of fiber insoluble like from
whole grains and soluble like from oat bran
and dried beans. A varied diet is important.
Types of Fiber:
There are several definitions of and ways to
classify fibers.
Fiber can be characterized in different ways,
either by analytical methods used to isolate
and quantify dietary fiber or by physiological
basis; solubility, fermentability or viscosity.
2002 Institute of Medicine Definition:
Total Fiber= Dietary + Functional
Dietary fiber : Non-digestible carbohydrate
and lignin that are intrinsic and intact in
plants.
Functional fiber: isolated non digestible CHO
that have beneficial physiological effects in
humans.
Physiological effectiveness is valuable way to
look at fibers for example the research on
inulin’s beneficial impact on digestive health.
Fiber and bowel function:
There is a lack of data examining the impact
of fiber from whole foods on outcomes in
gastrointestinal diseases (studies are difficult
to conduct). Fiber supplements may produce
benefits in the laxation of healthy people.
Many fibers sources (cereal brans, psyllium
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349.
Grabitske HA and Slavin JL. J Am
Diet Assoc. 2008;108:1677-1681
Grabitske HA and Slavin JL.
Laxation and the Like: Assessing
Digestive Health Nutrition Today
2008; 43(5):193-198.
Roberfroid M. J Nutr 2007;137
(suppl);830S-837S.
Aldorri et al. Can Fam Physician
2002;48:1632-1637
Institute of Medicine Food and
Nutrition Board. Dietary Reference
Intakes: Energy, Carbohydrate,
Fiber, Fat, Fatty Acids, Cholesterol,
Protein, and Amino Acids.
Washington D.C., National
Academies Press; 2002.
Attach spreadsheet of inulin
research.
http://www.isapp.net/
seed husks, methylcellulose and a mixed
high-fiber diet) increase stool weight, thus
promoting normal laxation.
If fiber is fully and rapidly fermented in the
large bowel (most soluble fibers are) there is
no increase in stool weight.
Stool weight varies greatly, Westernized
populations range from 80-120 g/day.
Tolerance:
Fiber is not digested and absorbed in the
small intestine, it can have a laxative effect
and increase the ease and/or frequency of
laxation.
Fiber is undigested. It is however utilized by
gut microbes as an energy source with gas
production as a byproduct of the
fermentation process.
Some effects potentially include:
Diarrhea, flatulence, bloating, and abdominal
discomfort. This may impact perception of
well-being and acceptance of high fiber foods
as part of the diet so it is important to couple
increased fiber recommendations with
education of what to expect.
When dietary fiber is increased, fluid intake
should also be increased.
Fiber should be increased gradually to allow
the GI tract time to adapt.
Other roles of fiber in health:
Prebiotics
International Scientific Association for
Probiotics and Prebiotics definition of
prebiotics: Prebiotics are selectively
fermented, dietary ingredients that result in
specific changes in the
composition and/or activity of the
gastrointestinal microbiota, thus conferring
benefit(s) upon host health. (i.e. providing fuel
for only beneficial types of bacteria at
expense of potentially pathogenic bacteria:
“feed the grass, not the weeds”)
Inulin is one of the best characterized
prebiotics.
Fructooligosaccharide (FOS) is rapidly
fermented by intestinal bacteria that then
produce short chain fatty acids (SCFA). SCFA
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stimulate water and electrolyte absorption
and may help treat diarrhea. FOS is also a
preferred substrate for bifidobacteria;
selectively stimulating growth of only
beneficial microorganism (again at the
expense of potentially pathogenic ones) so
can help maintain and restore balance of
healthful gut flora.
Role of Fiber in Diverticulosis:
Adequate intake of dietary fiber may prevent
formation of diverticula by providing bulk in
the colon. Case control and case studies
report success with high-fiber intakes and
diverticulosis, however it is not clear if
dietary fiber can prevent diverticulitis.
4. Probiotics role
in a healthy
immune
system
There are more and more probiotic product
options on the market in the form of medical
foods, supplements or foods. Not all probiotic
containing products are regulated the same
way; supplements less rigorously than foods.
There is potential to use food providing
prebiotics and probiotics to positively
modulate the gut microflora to help maintain
health.
Probiotics have been shown to impact
immune function by different mechanisms:
1. Via colonization resistance:
probiotics create an environment
that is more conducive to beneficial
bacteria growth which then crowdout potentially pathogenic
microorganisms in the alimentary
tract.
a. Ex: Reduction in GI infection
2. Interacting directly with the immune
cells in the gut.
a. Ex: some probiotic strains
have been shown to reduce
incidence of atopic
dermatitis/allergies in
children
Research is rapidly evolving regarding the
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Guarner et al., Nature Clinical
Practice Gastroenterology &
Hepatology 2006; 3(5): 275-284
Artis, D. nature Reviews
Immunology 2008; 8:411-420
(commensal bacteria and
immunity)
Reid et al., Clinical Microbiology
Reviews 2003; 16(4): 658–672
Servin A.L. Antagonistic activities
of Lactobacilli and Bifidobacteria
against microbial pathogens. FEMS
Microbiol Rev 2004; 28:405-440
(colonization resistance paper)
Merenstein D, et al. Europ J Clin
Nutr; 2010. (reduction in GI
infection)
Weizman et al., Pediatrics
2005;115:5–9; (infections study)
Chouraqui, et al., J Ped
Gastroenterol Nutr; 2004. 38: 288292 (infections study)
Smerud, H., et al., Microbial
influence of commensal (resident)
bacteria on shaping the immune system.
This could eventually lead to food based
solutions in the near future to impact
immunity.
Ecology in Health and Disease,
2008; 20:80-85 (infections study)
Kalliomaki, M., et al., Lancet; 2001.
357(9262): 1076-1079 (atopic
dermatitis study)
http://www.isapp.net/
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