Transcript File - Nutrition and Food Technology-just

Lower Gastrointestinal Tract
Chapter 17
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Anatomy
Duodenum, jejunum, ileum
Maximum surface area for digestion
and absorption (600 X)
• Folds of Kerckring
• Villi
• Microvilli – ”brush border”
Specialized enterocytes from stem
cells of crypts – high turnover = high
nutrient need
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Motility
Hormonal stimulation - gastrin
Peristaltic reflex – segmental
contractions
Mixing of chyme
MMC – motility when SI empty
• Motilin
Other hormones: CKK, orexin, leptin
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Secretions
Own secretions + digestive enzymes,
bicarbonate, bile
CCK, gastrin, secretin stimulate
release of pancreatic and gallbladder
secretions - see Table 17.1
• Bicarbonate – neutralizes gastric HCL
• Bile – emulsifies fat
• 1.5 L intestinal juices – water & mucus
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Digestion
 Protein digestion
• Trypsinogen, chymotrypsinogen,
procarboxypeptidases, elastase
• Enterokinase from brush border
• Peptidases
 Starch digestion
• Pancreatic amylase
• Lactase, maltase, sucrase, etc. from brush border
 Lipid digestion
• Pancreatic lipase, colipase
• Bile
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Absorption
Active transport utilizing Na/K pump
at brush border
• Glucose, galactose, amino acids
Facilitated diffusion
• Fructose
Lipids enter lymph via passive
diffusion
• First converted to micelles and packaged
as chlylomicrons
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Small Intestine Absorption
Steatorrhea – if lipid not absorbed
Most nutrients absorbed in duodenum
and jejunum
Ileum
• B12
• Reabsorption of bile – “enterohepatic
circulation”
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Anatomy
Ascending, transverse, descending,
sigmoid colon
No villi or microvilli
Crypts produce specialized epithelial
cells
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Motility
Haustration – segmentation; circular
muscles forms small sacs (haustra)
Propulsion
Mass movement
Defecation
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Secretions
Goblet cells produce mucus
Potassium and bicarbonate
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Digestion &
Absorption
No enzymatic digestion occurs
Reabsorption of water, electrolytes,
some vitamins
Formation and storage of feces
• Insoluble fiber, bilirubin
• 400 species of bacteria
• Fermentation of fiber and sugar alcohols
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Digestion &
Absorption
Fermentation produces SCFA and
lactate
Energy produced used by bacteria,
for tissue growth in colon or
utilization in body
Excess substrate = gas, flatulence
© 2007 Thomson - Wadsworth
Lower GI Tract – A&P
• Large Intestine Digestion &
Absorption
Maintaining balance of intestinal flora
• Resistant starches
• Prebiotics
• Probiotics
• Synbiotics
Vitamin K and biotin – endogenously
produced
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea – increase in frequency of
bowel movements or increase in
water content of stools
Affects consistency or volume
>200 g/day adults, >20 g/kg for
children
Dehydration secondary to diarrhea –
major global health issue
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea
Acute or chronic
Osmotic - increased water efflux due
to an increase in osmolality
• Maldigestion, excessive sorbitol or
fructose, enteral feeding, laxative use
• Resolves when NPO
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea
 Secretory - underlying disease causes
secretions
•
•
•
•
Does not resolve when NPO
Bacteria, protozoa, viruses
Traveler’s diarrhea
Medications, prostaglandins, excess bile acids or
unabsorbed fatty acids
• Antibiotic related
• GI diseases: Crohn’s, UC, celiac
• AIDS enteropathy, thyroid dysfunction
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea - Clinical Manifestations
Watery stool; increased frequency
Foul-smelling, frothy stools
Presence of blood
Abdominal pain & cramping
Dehydration, weight loss
Electrolyte and acid-base imbalances
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea - Diagnosis
Diagnose underlying etiology
Age, hydration status, presence of
blood in stool, immunocompetency
Recurrence of episodes related to
time of day and food intake
Stool cultures
Procedures such as endoscopy
Osmolality and electrolyte content
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea - Treatment
Treat underlying disease
Antibiotics
Restore fluid, electrolyte, acid-base
balance
IV therapy, rehydration solutions
Medications to treat symptoms
• See Table 17.12 - possible side effects
Suggest prevention strategies
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea - Nutrition Implications
Fluid losses – dehydration,
hyponatremia, hypokalemia
Metabolic acidosis
Malnutrition
Infants and elderly at greatest risk
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diarrhea - Nutrition Interventions
NPO or clear liquids – old
recommendation
Feed patient – stimulates recovery
Oral rehydration solutions
• WHO – see Table 17.4
• E.g. Pedialyte, Rehydralyte etc.
Low-residue diet, use of pectin
Pro- and prebiotics
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Constipation – decrease in
frequency of bowel movements
See Rome Consensus Criteria p. 474
Often hard, pellet-like
Abdominal pain, bloating, gas
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Constipation – Etiology
 Slowed colonic transit time
 Rectal outlet obstruction, fecal impactation,
adhesions, tumor
 Pelvic floor dysfunction
 IBS
 Other medical conditions; i.e. MS,
Parkinson’s
 Side effect of medications, supplements
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Constipation – Diagnosis/
Treatment
Complete hx & physical, CBC, TSH,
serum glucose
Colonoscopy, flexible sigmoidoscopy
Treat underlying etiology
Bowel retraining
Enemas, cathartic, laxatives
Bulking agents, stool softeners
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Constipation – Nutrition
 Increase whole grains, fruits, vegetables
 Fiber 20-35 grams/day
 Slowly increase fiber intake
 3:1 ratio insoluble to soluble fiber
• See Box 17.4
 Bulking agents
 Fluid – at least 2000 mL/day
 Pro- and prebiotics
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - maldigestion of
fat, CHO, pro.
Decreased villious height, enzyme
production; or dysfunction of
accessory organs d/t disease
Decreased transit time – surgery
See Table 17.5 – potential causes
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - fat
Steatorrhea - fat travels undigested
and unabsorbed to large intestine
Fat-soluble vitamins malabsorbed
Potential for excess oxalate
• Kidney stones, urothiasis, hyperoxaluria
Abdominal pain, cramping, diarrhea
Dg; fecal fat test or D-xylose
absorption test, or small bowel x-ray
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - Fat - Nutrition
Restrict fat 25-50 g/day
Use of MCT supplements
Pancreatic enzymes
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - CHO
Lactose malabsorption
Increased gas, abdominal cramping,
diarrhea
Dg: lactose tolerance test, lactose
breath hydrogen test
Restrict milk and dairy products
Products such as Lactaid can be rec.
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - protein
Protein-losing enteropathy –
excessive protein loss
Reduced serum protein
Peripheral edema d/t oncotic pressure
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Malabsorption - Nutrition Therapy
Results in weight loss,
vitamin/mineral deficiencies, chronic
PEM - See Table 17.6
Treat underlying disease/ nutrient
being malabsorbed
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Celiac disease - damage to
intestinal mucosa d/t exposure to
gluten
Genetic and autoimmune
Occurs when alpha-gliadin from
wheat, rye, malt, barley are eaten
Infiltration of WBC, production of IgA
antibodies
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Celiac disease - pathophysiology
Damage to villi; reduced height,
flattened
Decreased enzyme function and
surface area
Maldigestion and malabsorption
Occurs with other autoimmune
disorders
• Dermatitis herpetaformis, TIDM,
rheumatoid arthritis…
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Celiac disease - clinical manifestations
 Diarrhea, abdominal pain, cramping,
bloating, gas
 Bone and joint pain
 Muscle cramping, fatigue
 Peripheral neuropathy, seizures
 Skin rash
 Mouth ulcerations
 Higher risk for lymphoma and osteoporosis
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Celiac Disease Diagnosis/Treatment/Prognosis
Biopsy of small intestinal mucosa
Reversal of symptoms following
gluten-free diet
Identification of antibodies
Refractory CD; d/t coexisting disease
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Celiac Disease - Nutrition
Intervention
Low-residue, low-fat, lactose-free,
gluten-free diet
• Low-residue to minimize diarrhea
• Fat 45-50 g
• Gluten restriction for LIFE
• Oats controversial – limit to ½ c/day
Identify hidden sources of gluten
• See Table 17.7
Specialty products
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Irritable Bowel Syndrome (IBS) abdominal pain with 2 of the
following:
Pain relieved with defecation
Onset associated with change in
frequency of stool
Onset associated with change in form
of stool
• Eliminate “red flag” symptoms
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS
Most common GI complaint, women
more than men
Aggravated by stress, anxiety,
depression, emotional trauma
Etiology unknown
Increased serotonin, inflammatory
response, abnormal motility, pain
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS - pathophysiology
Increased sensitivity to stimulation of
GI tract
Resulting in abdominal pain, urgency,
diarrhea, constipation
Infectious and inflammatory
components
Stress
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS - clinical manifestations
Abdominal pain, alterations in bowel
habits, gas, flatulence
Increased sensitivity to certain foods:
lactose, wheat, high-fiber
Concurrent dg; fibromyalgia, chronic
fatigue syndrome, TMJ syndrome,
food allergies
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS - Treatment
Guided by symptoms
Antidiarrheal agents
Tricyclic antidepressants, SSRIs
Bulking agents, laxatives
Agonists or antagonists for 5-HT4
receptors
Behavioral therapies
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS - Nutrition Therapy
Can lead to nutrient deficiency,
underweight, malnutrition
Decrease anxiety, normalize dietary
patterns
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBS - Nutrition Therapy
Assess diet hx; offending foods
Assess nutritional adequacy
Focus on increasing fiber intake to 25
g/day
Adequate fluid
Pre- and probiotics
Avoid foods that produce gas and
swallowed air
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Inflammatory Bowel Disease (IBD)
- autoimmune, chronic
inflammatory condition of GI tract
Ulcerative colitis (UC)
Crohn’s disease
See Box 17.8 for comparison
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Etiology
Unknown
Environmental factors – smoking,
infectious agents, intestinal flora,
physiological changes in SI trigger
abnormal inflammatory response
Strong genetic association
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Pathophysiology
Exposure to certain triggers for those
genetically susceptible
Abnormal immune response
Release of cytokines
Destruction of mucosa
UC – primarily in colon; continuous
Crohn’s presents with “skipping”
pattern throughout GI
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - pathophysiology
UC - ulcerations lead to toxic
megacolon; thin, ulcerated colon
Crohn’s – fistulas, strictures,
obstruction
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - clinical manifestations
Abdominal pain, bloody diarrhea,
tenesmus
Febrile, tachycardic
CRP and ESR elevated
WBC elevated
Weight loss
See Box 17.9, Table 17.11 – Crohn’s
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Clinical manifestation/diagnosis
 Radiology testing
 Laboratory measures
 Antibody testing
 Observation of extraintestinal disease
•
•
•
•
•
Osteopenia
Osteoporosis
Dermatitis
Rheumatological conditions
Ocular and hepatobiliary complications
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Treatment
Antibiotics
Immunosupressants
Immunomodulators
Biologic therapies
Surgery
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Nutrition Therapy
Malnutrition; may require nutrition
support
May need to increase kcal, protein,
micronutrients
• Iron, zinc, magnesium, electrolytes
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Nutrition Interventions
During exacerbation – enteral
nutrition preferred over parenteral
Supplement glutamine, arginine
Assess energy needs + stress factor
May need to increase protein needs
1.5-1.75 g/kg
Low-residue, lactose-free diet
Small, frequent meals
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Nutrition Interventions
May use MCT oil if steatorrhea
present
Restrict gas-producing foods
Increase fiber and lactose as
tolerated
Advancement of oral diet –
individualized!
Multivitamin – B12, iron, zinc, calcium,
magnesium, copper, antioxidants
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• IBD - Nutrition Interventions
During remission/rehabilitation
• Maximize energy & protein
• Weight gain and physical activity
• Normalize dietary patterns
• Food sources of antioxidants, Omega-3s
• Limit foods high in oxalate
• Pro- and prebiotics
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diverticulosis/diverticulitis –
abnormal presence of outpockets
or pouches on surface of SI or
colon/ inflammation of these
Low fiber intake, hx of constipation,
increased colonic pressure
Increases inflammatory response
Other risks: obesity, sedentary,
steroids, alcohol and caffeine intake,
cigarette smoking
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diverticulosis/diverticulitis –
pathophysiology
 Fecal matter trapped, excessive pressure
against walls of colon
 Development of pouches
 Diverticulitis - when these pouches become
inflamed
 Food stuff and bacteria can collect and
result in infection
 Bleeding abscess, obstruction, fistula,
perforation
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diverticulosis/-itis – clinical
manifestations
-osis – asymptomatic
-itis - fever, abdominal pain, GI
bleeding, elevated WBC
Diagnosed by radiology testing
• Thickened walls, abscess, inflammation
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diverticulosis/-itis – Treatment/
Nutrition Therapy
Specific focus on fiber
Pro- and prebiotic supplementation
Acute – NPO with bowel rest
Antibiotics
Surgical resection
© 2007 Thomson - Wadsworth
Pathophysiology:
Lower GI Tract
• Diverticulosis/-itis – Nutrition
Therapy
-osis - high-fiber diet + 6-10 grams
Avoid nuts, seeds, hulls
Fiber supplement
-itis – low-fiber diet
Bowel rest, clear liquids
Avoid nuts, seeds, fibrous vegetables
© 2007 Thomson - Wadsworth
Surgical Interventions:
Lower GI Tract
• Ileostomy and Colostomy
Creation of a stoma
Ileostomy – colon and rectum are
removed
Colostomy - rectum removed
Pouch appliance used too collect
waste
See Fig. 17.12
© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Surgical Interventions:
Lower GI Tract
• Ileostomy and Colostomy –
Nutrition
Decrease risk of obstruction
Maintain fluid and electrolyte balance
Reduce fecal output
Minimize flatulence
After surgery transition to oral diet
• Clear liquids progress to low-residue
with 4-6 small meals/day
© 2007 Thomson - Wadsworth
Surgical Interventions:
Lower GI Tract
• Ileostomy and Colostomy –
Nutrition
Reduce risk for stoma obstruction
• Tough, fibrous meats, vegetables, dried
fruits, fruit skins, seeds, popcorn
• Eat slowly, chew thoroughly
• Drink adequate fluids
© 2007 Thomson - Wadsworth
Surgical Interventions:
Lower GI Tract
• Ileostomy and Colostomy –
Nutrition
Excessive, watery fecal output
• Reduce insoluble fiber and increase
soluble fiber
• Avoid foods that cause gas and flatulence
• Use of yogurt, parsley, buttermilk to
decrease gas and odor
Multivitamin and B12 supplementation
© 2007 Thomson - Wadsworth
Short Bowel Syndrome
• Short bowel syndrome - large
resection of small intestine
Less than 200 cm of functional SI
Extensive loss of surface area in SI
and colon
Malabsorption: nutrients, fluids,
electrolytes
© 2007 Thomson - Wadsworth
Short Bowel Syndrome
• Short bowel syndrome
Prognosis depends on length of
remaining small bowel, health of
remaining GI, any co-morbid
conditions
Major vitamin and mineral losses
Fat malabsorption – Vit. A, D, E, K
Sodium, Mg, iron, zinc, selenium,
calcium loss
© 2007 Thomson - Wadsworth
Short Bowel Syndrome
• Short bowel syndrome
Postoperative period - 3 distinct
phases
• 7-10 days: Extensive fluid and electrolyte
losses, large volume of diarrhea, TPN
• Several months: Reduced diarrhea
volume, adaptation of remaining bowel,
enteral nutrition, transition to oral diet
• 1-2 years: Continued adaptation of
bowel, intestinal tract increases in length,
diameter, and villous height
© 2007 Thomson - Wadsworth
Short Bowel Syndrome
• Short bowel syndrome - treatment
Manage fluid and electrolytes
Oral rehydration solutions
Medications for motility, diarrhea and
gastric hypersecretion
© 2007 Thomson - Wadsworth
Short Bowel Syndrome
• Short bowel syndrome – nutrition
 TPN postoperatively
 Oral diets introduced as diarrhea decreases
 May require combination of TPN and enteral
nutrition
 Sugar-free, isotonic clear liquids introduced
first
 Progress slowly to low-residue, low-fat,
lactose-free, low-oxalate diet
 Avoid caffeine and alcohol
 Avoid sugar alcohols and insoluble fiber
 See Table 17.15
© 2007 Thomson - Wadsworth
Bacterial Overgrowth
• Bacterial overgrowth resulting
from cross contamination of
bacteria from colon to SI
• Motility of GI tract delayed
• Bacteria competes with host for
nutrients
• Maldigestion, malabsorption,
weight loss
© 2007 Thomson - Wadsworth
Bacterial Overgrowth
• Clinical manifestations/treatment
Diarrhea, steatorrhea, anemia,
weight loss
Dg with hydrogen breath test
Antibiotics
Fat and lactose eliminated initially
Identify and treat nutrient of
malabsorption
© 2007 Thomson - Wadsworth