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==What is Fibre?==

==What is Fibre?==

Fibres are [[Nutrition Glossary#Polysaccharides|'''polysaccharides''']] that are resistant to hydrolysis by mammalian digestive enzymes. These include substances such as '''cellulose, hemi-cellulose, pectin''' and '''lignin''' which are '''key structural components of plant cell walls'''. Although fibre is most commonly associated with plant materials, fibre like substances such as chitin are present in fungi, crustaceans and insects. Over recent years the definition of dietary fibre has been expanded to include substances such as resistant starch, inulin and non-digestible oligosaccharides

Fibres are [[Nutrition Glossary#Polysaccharides|'''polysaccharides''']] that are resistant to hydrolysis by mammalian digestive enzymes. These include substances such as '''cellulose, hemi-cellulose, pectin''' and '''lignin''' which are '''key structural components of plant cell walls'''. Although fibre is most commonly associated with plant materials, fibre like substances such as chitin are present in fungi, crustaceans and insects. Over recent years the definition of dietary fibre has been expanded to include substances such as '''resistant starch, inulin''' and '''non-digestible oligosaccharides'''.

Fibre is resistant to degradation because mammalian digestive enzymes cannot break the glycoside linkages between sugar monomers.

Fibre is resistant to degradation because mammalian digestive enzymes cannot break the glycoside linkages between sugar monomers.

Fibres, can be classified by their capacity to dissolve in water (soluble or insoluble), form a gel-like consistency (viscous or non-viscous), and/or for fermentation by colonic bacteria (fermentable or non-fermentable)<ref>Luptin JR and Turner ND. Dietary Fiber. In Biochemical and Physiological Aspects of Human Nutrition. 2000 Philadelphia, PA: WB Saunders Company p.143-154.</ref>. Soluble, viscous, fermentable fibres are those that form gels within the gastrointestinal tracts, such as pectin, gums, mucilage, and some hemicelluloses. Insoluble, non-viscous, non-fermentable fibres remain relatively unchanged after consumption and include cellulose, lignin, and some hemicelluloses. Resistant starches are formed from absorbable starch during the cooking process and will act as fermentable fibre in the intestinal lumen.

'''Fibres can be classified by their capacity to dissolve in water (soluble or insoluble), form a gel-like consistency (viscous or non-viscous), and/or for fermentation by colonic bacteria (fermentable or non-fermentable)'''<ref>Luptin JR and Turner ND. Dietary Fiber. In Biochemical and Physiological Aspects of Human Nutrition. 2000 Philadelphia, PA: WB Saunders Company p.143-154.</ref>.  

*Soluble, viscous, fermentable fibres are those that form gels within the gastrointestinal tracts, such as pectin, gums, mucilage, and some hemicelluloses.  

*Insoluble, non-viscous, non-fermentable fibres remain relatively unchanged after consumption and include cellulose, lignin, and some hemicelluloses.  

*Resistant starches are formed from absorbable starch during the cooking process and will act as fermentable fibre in the intestinal lumen.

==Why is it Important?==

==Why is it Important?==

==Roles in the Body==

==Roles in the Body==

Increasing viscosity of ingesta will slow transit out of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] and through the [[:Category:Small Intestine - Anatomy & Physiology|small intestine]]<ref>Bueno L, et al. Effect of dietary fiber on gastrointestinal motility and jejunal transit time in dogs. Gastroenter 1980;80:701-707.</ref><ref>Lewis LD, et al. Stool characteristics, transit time, and nutrient digestibility in dogs fed different fiber sources. J Nutr 1994;124:2716S-2718S.</ref>. This can promote a feeling of satiety, but can also delay or hinder nutrient absorption. The presence of viscous fibres can interfere with fat absorption<ref>Muir HE, et al. Nutrient digestion by ileal cannulated dogs as affected by dietary fibers with various fermentation characteristics. J Anim Sci 1996;74:1641-8.</ref><ref name="Mimura">Mimura K, et al. Impact of commercially available diabetic prescription diets on short term postprandial serum glucose, insulin, triglyceride and free fatty acid concentrations of obese cats. J Vet Med Sci 2013;75:929-937.</ref> and can slow starch digestion and glucose absorption, dampening post-prandial rises in blood sugar<ref name="Mimura"/><ref>Nguyen P, et al. Glycemic and insulinemic response after ingestion of commercial foods in healthy dogs: Influence of food composition. J Nutr 1998;128:2654S-2658S.</ref>.

Increasing viscosity of ingesta will slow transit out of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] and through the [[:Category:Small Intestine - Anatomy & Physiology|small intestine]]<ref>Bueno L, et al. Effect of dietary fiber on gastrointestinal motility and jejunal transit time in dogs. Gastroenter 1980;80:701-707.</ref><ref>Lewis LD, et al. Stool characteristics, transit time, and nutrient digestibility in dogs fed different fiber sources. J Nutr 1994;124:2716S-2718S.</ref>. This can promote a feeling of satiety, but can also delay or hinder nutrient absorption. The presence of viscous fibres can interfere with [[Digestibility of Fat|fat absorption]]<ref>Muir HE, et al. Nutrient digestion by ileal cannulated dogs as affected by dietary fibers with various fermentation characteristics. J Anim Sci 1996;74:1641-8.</ref><ref name="Mimura">Mimura K, et al. Impact of commercially available diabetic prescription diets on short term postprandial serum glucose, insulin, triglyceride and free fatty acid concentrations of obese cats. J Vet Med Sci 2013;75:929-937.</ref> and can slow [[Digestibility of Carbohydrates|starch digestion]] and glucose absorption, dampening post-prandial rises in blood sugar<ref name="Mimura"/><ref>Nguyen P, et al. Glycemic and insulinemic response after ingestion of commercial foods in healthy dogs: Influence of food composition. J Nutr 1998;128:2654S-2658S.</ref>.

Fermentable dietary fibres are utilized by bacteria within the large intestine to produce H₂ (hydrogen gas), CO₂ (carbon dioxide), CH₄ (methane), and the short-chain fatty acids, acetate, propionate, and butyrate. Acetate and propionate are rapidly absorbed across the large intestinal mucosa with [[Sodium - Nutrition|sodium]] (Na²⁺) and are responsible for water absorption in the [[:Category:Large Intestine - Anatomy & Physiology|large intestine]]<ref>Herschel DA, et al. Absorption of volatile fatty acids and H2O by the colon of the dog. AJVR 1981;42:1118-1124.</ref>. Acetate and propionate can then be further utilized by the host animal, and can contribute up to 10% of energy intake<ref>Rerat A. Digestion and absorption of carbohydrates and nitrogenous matters in the hindgut of the ombivorous nonruminant animal. J Anim Sci 1978;46:1808-1837.</ref>. Butyrate remains in the large intestine where it is used as the preferred energy substrate by colonocytes. Increased intake of fermentable fibre has been shown to increase colonic weight and villus height in dogs<ref>Reinhart GA, et al. Source of dietary fiber and its effects on colonic microstructure, function and histopathology of beagle dogs. J Nutr 1994;124:2701S-2703S.</ref>.

Fermentable dietary fibres are utilized by bacteria within the large intestine to produce H₂ (hydrogen gas), CO₂ (carbon dioxide), CH₄ (methane), and the short-chain fatty acids, acetate, propionate, and butyrate. Acetate and propionate are rapidly absorbed across the large intestinal mucosa with [[Sodium - Nutrition|sodium]] (Na²⁺) and are responsible for water absorption in the [[:Category:Large Intestine - Anatomy & Physiology|large intestine]]<ref>Herschel DA, et al. Absorption of volatile fatty acids and H2O by the colon of the dog. AJVR 1981;42:1118-1124.</ref>. Acetate and propionate can then be further utilized by the host animal, and can contribute up to 10% of energy intake<ref>Rerat A. Digestion and absorption of carbohydrates and nitrogenous matters in the hindgut of the ombivorous nonruminant animal. J Anim Sci 1978;46:1808-1837.</ref>. Butyrate remains in the large intestine where it is used as the preferred energy substrate by colonocytes. Increased intake of fermentable fibre has been shown to increase colonic weight and villus height in dogs<ref>Reinhart GA, et al. Source of dietary fiber and its effects on colonic microstructure, function and histopathology of beagle dogs. J Nutr 1994;124:2701S-2703S.</ref>.

Insoluble fibres will also increase faecal bulk and dry matter content<ref>Fahey GC Jr, et al. Dietary fiber for dogs. II. Isolated total dietary fiber (TDF_ additions of divergent fiber sources to dog diets and their effects on nutrient intake, digestibility, metabolic energy and digesta mean retention time. J Anim Sci 1990;68:4229-4235.</ref>, a feature that is used in some pet foods to dilute calorie density for weight management, though efficacy at decreasing energy intake is inconsistent<ref>German AJ, et al. A high protein high fibre diet improves weight loss in obese dogs. Vet J 2010;183:294-297. </ref><ref>Butterwick FR, et al. Effect of level and source of dietary fiber on food intake in the dog. J Nutr 1994;124:2695S-2700S.</ref>. Increased dietary fibre intake has also been used as an adjunct therapy to insulin administration to improve [[Nutrition Glossary#Glycaemic Response|glycaemic response]] in diabetic cats and dogs<ref>Nelson RW. The role of fiber in managing diabetes mellitus. Vet Med 1989;84:1156-1160.</ref><ref>Nelson RW, et al. Effect of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus. JAVMA 2000;216:1082-1088.</ref>. Decreased cholesterol and triglyceride absorption may also occur with increased intake of soluble, fermentable fibre<ref>Ikedo I, et al. Interrelated Effects of Dietary Fiber and Fat on Lymphatic Cholesterol and Triglyceride Absorption. J Nutr 1989;199:1383-1387.</ref>.

Insoluble fibres will also increase faecal bulk and dry matter content<ref>Fahey GC Jr, et al. Dietary fiber for dogs. II. Isolated total dietary fiber (TDF_ additions of divergent fiber sources to dog diets and their effects on nutrient intake, digestibility, metabolic energy and digesta mean retention time. J Anim Sci 1990;68:4229-4235.</ref>, a feature that is used in some pet foods to dilute calorie density for weight management, though efficacy at decreasing energy intake is inconsistent<ref>German AJ, et al. A high protein high fibre diet improves weight loss in obese dogs. Vet J 2010;183:294-297. </ref><ref>Butterwick FR, et al. Effect of level and source of dietary fiber on food intake in the dog. J Nutr 1994;124:2695S-2700S.</ref>. Increased dietary fibre intake has also been used as an adjunct therapy to [[insulin]] administration to improve [[Nutrition Glossary#Glycaemic Response|glycaemic response]] in diabetic cats and dogs<ref>Nelson RW. The role of fiber in managing diabetes mellitus. Vet Med 1989;84:1156-1160.</ref><ref>Nelson RW, et al. Effect of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus. JAVMA 2000;216:1082-1088.</ref>. Decreased cholesterol and triglyceride absorption may also occur with increased intake of soluble, fermentable fibre<ref>Ikedo I, et al. Interrelated Effects of Dietary Fiber and Fat on Lymphatic Cholesterol and Triglyceride Absorption. J Nutr 1989;199:1383-1387.</ref>.

==Consequences of Fibre Deficiency==

==Consequences of Fibre Deficiency==

==Toxicity==

==Toxicity==

Excessive intake of non-absorbable carbohydrates (both fermentable and non-fermentable dietary fibres) may potentially result in either diarrhoea or constipation in healthy dogs and cats depending on fibre type (viscous, fermentable vs. non-fermentable, respectively). Increased dietary fibre can also decrease protein digestibility<ref name="Kerr"/><ref>Silvio J, et al. Influences of fiber fermentation on nutrient digestion in the dog. Nutr 2000;16:289-295.</ref>, which may be contraindicated in animals with underlying intestinal disease, and high dietary fibre intake can interfere with mineral absorption<ref>Fernandez R and Phillips SF. Components of fiber impair iron absorption in the dog. Am J Clin Nutr 1982:35:107-112.</ref>. High intake of dietary fibre also results in energy dilution and animals may be unable to consume sufficient amounts of food to meet energy needs.

Excessive intake of non-absorbable carbohydrates (both fermentable and non-fermentable dietary fibres) may potentially result in either [[diarrhoea]] or [[Colonic Impaction - Dog and Cat|constipation]] in healthy dogs and cats depending on fibre type (viscous, fermentable vs. non-fermentable, respectively). Increased dietary fibre can also decrease [[Digestibility of Protein|protein digestibility]]<ref name="Kerr"/><ref>Silvio J, et al. Influences of fiber fermentation on nutrient digestion in the dog. Nutr 2000;16:289-295.</ref>, which may be contraindicated in animals with underlying intestinal disease, and high dietary fibre intake can interfere with mineral absorption<ref>Fernandez R and Phillips SF. Components of fiber impair iron absorption in the dog. Am J Clin Nutr 1982:35:107-112.</ref>. High intake of dietary fibre also results in energy dilution and animals may be unable to consume sufficient amounts of food to meet energy needs.

==Dietary Sources==

==Dietary Sources==

Dietary fibre is found in fruits, vegetables, cereal grains, and pulses (i.e., legumes). Chitin is present in fungi and the exoskeleton of crustaceans and insects. Common pet food fibre sources, such as beet pulp and fruit (e.g., citrus, tomato, apple) pomaces are derived from the human food industry.  

Dietary fibre is found in fruits, vegetables, cereal grains, and pulses (i.e., legumes). Chitin is present in fungi and the exoskeleton of crustaceans and insects. Common pet food fibre sources, such as beet pulp and fruit (e.g., citrus, tomato, apple) pomaces are derived from the human food industry.  

Crude fibre as listed on a pet food label is a measure of insoluble, non-fermentable fraction of total dietary fibre and does not reflect the actual amount or distribution of fibre within a commercial diet<ref>Farcas AK, et al. Evaluation of fiber concentration in dry and canned commercial diets formulated for adult maintenance or all life stages of dogs by use of crude fiber and total dietary fiber methods. JAVMA 2013;242:936–940.</ref>.

'''Crude fibre as listed on a pet food label is a measure of insoluble, non-fermentable fraction of total dietary fibre and does not reflect the actual amount or distribution of fibre within a commercial diet'''<ref>Farcas AK, et al. Evaluation of fiber concentration in dry and canned commercial diets formulated for adult maintenance or all life stages of dogs by use of crude fiber and total dietary fiber methods. JAVMA 2013;242:936–940.</ref>.

==Diagnosing Fibre Deficiency==

==Diagnosing Fibre Deficiency==

[[Category:Carbohydrates]]

[[Category:Carbohydrates]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition GGP]]

[[Category:To Do - Nutrition preMars]]