Page 70 - Small Animal Clinical Nutrition 5th Edition

70 Small Animal Clinical Nutrition

to more hydrogen in expired breath and flatus and short-chain RESISTANT STARCH
RS (Table 5-5) is a fraction of starch found in foods that
VetBooks.ir fatty acids in stools. Animals with deranged carbohydrate potentially resists digestion in the small intestine (Englyst and
metabolism (diabetes mellitus, ketosis, glycogen storage dis-
Cummings, 1987). RS is classified according to the rapidity
eases and fructose, galactose and pyruvate enzyme deficiencies)
may have elevated urinary or plasma levels of the metabolic with which glucose is released from a starch source and is a
intermediates related to the specific disease (glucose, ketones, fraction of the total amount of starch that remains after a sam-
lactic acid, oxalate, etc.). Chapter 29 discusses treatment of the ple is incubated for 100 minutes with the enzymes pancreatin
most common disease of abnormal carbohydrate metabolism, and amyloglucosidase. Four types of RS have been identified
diabetes mellitus. (Brown, 1996):
RS = starch physically trapped within the starch granule
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Carbohydrates of Special Importance that is released during processing and chewing.
XYLOSE RS = starch granular structures (e.g., those found in raw
2
Xylose is a five-carbon sugar used in clinical veterinary med- potato, bananas and tapioca).
icine to assess intestinal absorptive capacity, alterations in GI RS = recrystallized starch formed after cooking, when the
3
emptying, bacterial overgrowth and exocrine pancreatic insuffi- starch cools or is dried.
ciency (Chapters 54, 60 and 66). When xylose is administered RS = chemically modified starch resistant to enzymatic
4
orally, approximately 48% is expected to be absorbed into the hydrolysis.
bloodstream and excreted in urine (Williams and Guilford, RS and RS represent the residues of starches that are
2
1
1996). Altered xylose absorption can be diagnostic for certain digested very slowly and incompletely in the small intestine.
diseases. The xylose absorption test is typically only recom- RS is highly resistant to digestion by intestinal enzymes and is
3
mended for use in dogs; there is too much individual variabili- fermented by colonic bacteria.
ty in results from cats (Williams and Guilford, 1996). Physiologically, RS are thought to have various functions
related to their dietary fiber-like properties including reducing
LACTULOSE the glycemic index of food, decreasing the glucose and insulin
Lactulose is a synthetic disaccharide containing galactose responses to food and improving bowel health (Brown et al,
and fructose connected by a β1,4 bond. Lactulose is formed 2001). In particular, RS can be used as a source of fiber for
when lactose (galactose and glucose) is subjected to isomeriza- gluten-free or hypoallergenic foods.
tion in aqueous alkaline solutions. Lactulose is not hydrolyzed
by mammalian enzymes, but can be digested by microbial OLIGOSACCHARIDES
enzymes; thus, it is fermented in the colon. Lactulose enhances Oligosaccharides are polymers that contain up to nine sug-
the growth of specific types of bacteria (Lactobacillus bifidus), ars. Oligosaccharides that contain fructose are termed fruc-
has laxative effects and acidifies the colon to aid in ammonia tooligosaccharides (FOS). Although FOS are the most exten-
trapping. Fermentation of excessive amounts of lactulose may sively studied oligosaccharides, other oligosaccharides include
worsen flatulence and cause diarrhea. Clinically, lactulose is mannanoligosaccharides (MOS), galactooligosaccharides
often given to help manage hepatic encephalopathy (Chapter (GOS), xylooligosaccharides (XOS), isomaltooligosaccharides
68).(It is also occasionally administered before breath hydrogen (IMOS), soybean oligosaccharides (SOS), pectic oligosaccha-
collection and used with a xylose absorption test to differenti- rides, chitooligosaccharide, lactusucrose and lactulose or other
ate among small intestinal disease, bacterial overgrowth and polysaccharide/oligosaccharide-containing sources such as
exocrine pancreatic insufficiency (Chapters 55, 60 and 66). inulin. Oligosaccharides resist digestion by enzymes in the
small intestine and enter the colon intact. In the colon, certain
GLYCOSAMINOGLYCANS bacteria (bifidobacteria and Lactobacillus spp.) readily ferment
Glycosaminoglycans are complex polysaccharides associated oligosaccharides, which enhances the bacterial growth rate
with proteins. They form integral parts of the interstitial fluid, (Roberfroid et al, 1998, 1993; Gibson and Roberfroid, 1995;
cartilage, skin and tendons. The primary glycosaminoglycans Hidaka et al, 1986; Bunce et al, 1995, Flickinger et al, 2000;
are chondroitin sulfate and hyaluronic acid. Chondroitin sulfate Grieshop et al, 2004). Increased numbers of these bacterial
is a polymer of two alternating sugar units, glucuronic acid and species may benefit the overall health of people and other ani-
N-acetylgalactosamine. Hyaluronic acid is a linear polymer of mals, including pigs, rabbits and rats (Bunce et al, 1995;
two sugars: glucuronic acid and N-acetylglucosamine. Willard et al, 1994; Howard et al, 1995).
Chondroitin sulfate and other glycosaminoglycans are available Bifidobacteria produce short-chain fatty acids that decrease
as dietary supplements with alleged benefits for arthritic condi- the intestinal pH and inhibit the growth of pathogenic bacte-
tions, degenerative joint diseases and geriatric patients in gen- ria. FOS reduce fasting blood glucose levels, cholesterol and
eral. In one study using a combination of oral chondroitin sul- low-density lipoproteins (LDL) in people with diabetes melli-
fate and glucosamine in human patients with osteoarthritis of tus (Yamishita et al, 1984). The benefits of oligosaccharides
the knee joint, there was no pain relief in the overall patient such as FOS, MOS and GOS in dogs, pigs, rabbits and rats
population, but there was some benefit for patients with mod- include improved intestinal flora (i.e., reduced numbers of
erate to severe pain (Clegg et al, 2006). pathogens), reduced mortality, improved feed efficiency,