A review of interactions between dietary fibre and the intestinal mucosa, and their consequences on digestive health in young non-ruminant animals

Dietary fiber is a general term. It covers a wide variety of substances that belong to the family of carbohydrates that resist hydrolysis by human alimentary enzymes but are fermented by colonic microflora. The main physiological effects of dietary fiber are primarily on gastric emptying and small intestinal transit time, resulting in an improved glucose tolerance and a decreased digestion of starch: second, on colonic transit time and large bowel functions due to fermentation by ceco-colonic microbial flora or bulking action. The so-called soluble dietary fibers are fermented to a large extent by a wide variety of anaerobic bacteria that result in an increase in bacterial biomass, an increase in fecal mass, a change in intracolonic pH, and production of short chain fatty acids and various gases as metabolic end products. The insoluble fibers are only marginally fermented: they serve almost exclusively as bulking agents that result in shorter transit time and increased fecal mass. The short chain fatty acids resulting from the colonic fermentation of dietary fiber are largely absorbed via the portal blood and reach both the liver and the peripheral tissues. They induce changes in glucose and fat metabolism leading to post-prandial hypoglycemia and long-term hypolipidemia. Inulin and oligofructose are fructans with a degree of polymerization of 2 to 60 and 2 to 20, respectively. Due to the structural conformation of their osidic bridge (beta 2-1), they both resist the hydrolysis by human alimentary enzymes. Moreover, when reaching the colon, both inulin and oligofructose are almost quantitatively fermented almost exclusively by colonic bifidobacteria and bacteroides. Such an extensive fermentation causes an increase in fecal bacterial biomass, a decrease in ceco-colonic pH, and produces a large amount of fermentation products among which the short chain fatty acids that exert systemic effects on lipid metabolism. Thus, both inulin and oligofructose have most of the characteristics of a dietary fiber and the proposal is made to classify them as such. Moreover, they are bifidogenic factors, because, due to still unknown reasons, they are primarily fermented by bifidobacteria. It is concluded from this review that "nondigestible fructo-oligosaccharides," even though they are not included in the carbohydrate fraction that is quantified as dietary fiber by classic analytical methods, have most of the physiological effects of a dietary fiber.(ABSTRACT TRUNCATED AT 400 WORDS)

Dietary fiber, inulin, and oligofructose: a review comparing their physiological effects

1. The mechanism of the anti-nutritive activities of soluble non-starch polysaccharides (NSPs) in broiler diets was investigated with emphasis on the inter-relationship between viscosity and fermentation along the gut. Isolated soluble NSP were added to a control diet to effect high gut viscosity, and in vivo depolymerisation of the NSP was achieved using a commercial glycanase. 2. Addition of soluble NSPs significantly (P < 0.01) increased gut viscosity, reduced the AME of the diet and depressed the growth and FCE of the birds. Enzyme supplementation of the NSP-enriched diet reversed the adverse effects, increasing (P < 0.01) weight gain, FCE and AME. Comparisons of the viscosities (mPa) in birds fed on the NSP-enriched diet and the same diet supplemented with enzyme were respectively: 11.9 v. 2.3 in the duodenum; 78.3 v. 4.4 in the jejunum and 409.3 v. 10.8 in the ileum. 3. Caecal volatile fatty acid concentration was markedly (P < 0.01) elevated by enzyme supplementation, whereas ileal fermentation was inhibited. 4. Microscopic examination revealed that, among birds fed on the NSP-enriched diet, there had been extensive small intestinal fermentation, which was eliminated by the enzyme supplementation. 5. Addition of a synthetic antibiotic (Amoxil) had no beneficial effects. 6. The current study demonstrated that increased fermentation occurs in the small intestine when a large amount of viscous NSPs is present in the diet and this is detrimental to the performance and well-being of poultry.

Increased small intestinal fermentation is partly responsible for the anti‐nutritive activity of non‐starch polysaccharides in chickens

Viscosity is a physicochemical property associated with dietary fibers, particularly soluble dietary fibers. Viscous dietary fibers thicken when mixed with fluids and include polysaccharides such as gums, pectins, psyllium, and β-glucans. Although insoluble fiber particles may affect viscosity measurement, viscosity is not an issue regards insoluble dietary fibers. Viscous fibers have been credited for beneficial physiological responses in human, animal, and animal-alternative in vitro models. The following article provides a review of viscosity as related to dietary fiber including definitions and instrumentation, factors affecting viscosity of solutions, and effects of viscous polysaccharides on glycemic response, blood lipid attenuation, intestinal enzymatic activity, digestibility, and laxation.

Viscosity as Related to Dietary Fiber: A Review

1 The mechanism of the anti-nutritive activity of isolated wheat pentosans was investigated by examining the roles of digesta viscosity and gut microflora in broiler chickens 2 Wheat pentosans were isolated by alkaline extraction and purified by sequential treatment with pancreatin, alpha-amylase and lichenase, and high-speed centrifugation Some of the pentosans were depolymerised using a beta-xylanase, which reduced the relative viscosity of the polysaccharides 4 fold 3 Inclusion of 35 g alkali-extractable pentosans (containing 854 g arabinoxylans/kg DM) per kg diet significantly (P less than 005) depressed broiler performance and the viscosity of the digesta of these birds was significantly (P less than 005) higher than that of controls Addition of the same amount of depolymerised pentosans had no significant effect on bird performance and had less effect on digesta viscosity 4 Supplementation of the diet containing wheat pentosans (30 g/kg) with procaine penicillin (150 mg/kg) did not improve bird performance 4 It is concluded that the wheat pentosans elicit their anti-nutritive activity predominantly through increasing the viscosity of digesta

Anti‐nutritive effect of wheat pentosans in broiler chickens: Roles of viscosity and gut microflora

Effects of viscous indigestible polysaccharides on the pancreas exocrine function were investigated in growing rats. Rats were fed a nonfiber diet or a diet containing approximately 5% of one of the following fibers: apple pectin, lambda-carrageenan, locust bean gum, gum xanthan, guar gum or sodium (Na) alginate. Pancreatic-bile secretion was found to be elevated in rats fed for 2 wk the highly viscous polysaccharides, sodium alginate, locust bean gum, gum xanthan and guar gum. The polysaccharides may have interfered with the digestion and absorption of nutrients, resulting in a decreased digestibility and an enlargement of digestive organs. When alginic acid and calcium alginate, insoluble polysaccharides that did not contribute to viscosity, were given to rats, they had no effect on pancreatic and biliary secretion compared with sodium alginate. The results demonstrate that consumption of viscous indigestible polysaccharides leads to changes in the exocrine pancreatic-biliary function and may depress the process of digestion and absorption. Rats may compensate for the inefficiency of digestion and absorption with a hyperplasia/hypertrophy of digestive organs and an increased secretion of digestive juice.

Effect of viscous indigestible polysaccharides on pancreatic-biliary secretion and digestive organs in rats

血糖値の変化に対する大麦の影響を明らかにするために正常動物と実験的糖尿病発症動物を用いて検討した。実験にはSprague Dawley系雄ラットを用い, 糖尿病動物はストレプトゾトシン (40mg/kg体重) を腹腔内投与して作成した。実験Iでは4週齢ラットに大麦食, 玄米食, 小麦ふすま食, α-コーンスターチ食を64日間摂取させた。その後すべてのラットを糖尿病とした。糖尿病を発症させた後のラットの体重は大麦食と玄米食のみ増加が見られたが大麦食では飼料摂取量はもっとも低かった。正常期ラットの飼料摂取後およびグルコース負荷後の血糖値は大麦食摂取ラットで低く, 糖尿病発症後でもグルコース負荷後の血糖値は大麦食での抑制が顕著であった。大麦食-糖尿病ラットでは腹腔内へのグルコース負荷でも血糖値の上昇が抑制されており, 体内における糖代謝の改善が認められた。さらに塘尿病発症後の空腹時血糖値は, 25日目には大麦食ではほぼ塘尿病発症前のレベルに回復し, 47日後の血清インスリンはα-コーンスターチ群より有意に高くなっていた。実験IIでは大麦とα-コーンスターチ食を摂取させて, 正常ラットと糖尿病ラットの間で比較した。糖尿病発症後33日目では大麦食ラットは, グルコース負荷後の血糖値の変化はα-コーンスターチ食-正常ラットよりむしろ低くなっていた。以上の結果より, 大麦は糖尿病患者の治療食として用いた場合に糖代謝の改善が期待されることが示唆された。

Effect of Barley on Development of Experimental Diabetes in Rats.

The present experiments were conducted to clarify the effects of organochlorine pesticides on the lipid components of serum and liver, and lipid peroxide in the liver of rats. Male Sprague Dawley rats aged 4 weeks were fed diets containing seven pesticides (TPN, chlorbenzilate, β-HCH, p, p′-DDT, heptachlor, dieldrin and endrin) for 2 weeks. The changes of biochemical parameters caused by inducers (phenobarbital and 3-methylcholanthrene) and the pesticides were compared.1. Total cholesterol and HDL-cholesterol in serum increased in rats fed p, p′-DDT, heptachlor, dieldrin and the inducers. Phospholipid in serum increased in rats fed p, p′-DDT, heptachlor and the inducers.2. Phospholipid and cholesterol in liver increased in rats fed β-HCH, p, p′-DDT and the inducers, and in rats fed chlorbenzilate, β-HCH, p, p′DDT and the inducers, respectively.An increase of total lipid in liver was observed in rats fed p, p′-DDT, heptachlor, dieldrin and the inducers, accompanied with an increase of triglyceride in rats fed p, p′-DDT, heptachlor and phenobarbital.3. Hepatic lipid peroxide significantly increased in rats fed p, p′-DDT, heptachlor and phenobarbital. Induction of cytochrome c reductase was observed in rats fed the pesticides except TPN and endrin, and phenobarbital. Production of lipid peroxide was closely related to triglyceride concentration and activity of cytochrome c reductase.

https://www.jstage.jst.go.jp/article/shokueishi1960/32/4/32_4_284/_pdf

Changes in Lipid Components in Liver and Serum and Production of Lipid Peroxide in Liver by Organochlorine Pesticides in Rats

酵素-重量法によって, 52種の食品の食物繊維含量を分析した。穀類では12種の食品を分析した。精白米, もち米の食物繊維含量は0.87%と0.66%ときわめて低かった。小麦粉, そば粉, 大麦, ライ麦, オートミールでは, NDF法によって測定されている値よりかなり高くなった。いも類は3種を分析したが, NDF法による値よりも高く, また, じゃがいも, さつまいもは蒸すことによって食物繊維含量は高くなった。豆類では8種を分析したが, 15～20%と高い食物繊維含量であった。これらはNDF法で得られている分析値の約2倍である。野菜類は15種を分析したが, 1～3%の範囲に入るものが多かった。ごぼうは10.89%と食物繊維含量が高かった。きのこ類は8種を分析したが, 生のものでは1～3%の範囲に入るものが多かった。NDF法で得られている値より低くなったが, その理由は明らかではない。海藻類は16種を分析したが, いずれも食物繊維含量が高かった。こんぶ, わかめ, ひじきの硫酸分画法による分析値が報告されているが, それらの値の1.5～3.2倍の値であった。

Determination of total dietary fiber in foods and food products by the enzymatic-gravimetric method.

DFの簡便な定量法として従来から用いられてきた中性デタージェント法 (ND法) と, 最近提案された酵素-重量法について, それぞれ数機関によるクロスチェックを行い, 問題点を明らかにし, その改良を試みた。ND法は, 5種の同一試料 (穀類) を用いて6機関で, まずはじめにそれぞれの機関における方法で分析を行った。その結果にもとづいて酵素反応時間を短縮するためにターマミル60Lを用い, また濾過補助剤としてセライトを用いることによって濾過時間の短縮をはかり, 改めて2回目の分析を行ったところ, 変動係数に大きな改良がみられた。酵素-重量法は, ProskyらおよびAOAC法を基本として, 試料の処理方法, セライトの洗浄, 酵素反応時間, 計算式などを改良した。この方法により, 穀類, 豆類および精製DFなど6種の同一試料を4機関で分析した。その結果, Proskyらの報告にくらべて変動係数の大幅な改善がみられたが, 精白米のようにDF含量が少なく, デンプンの多い食品では変動係数が大きくなることがわかった。酵素-重量法とSouthgate法を5種の試料に適用したところ, 同一試料についての両者で求めた総DF量の値の差は比較的小さかった。しかし大麦については, ND法の値が酵素-重量法の値のほぼ2分の1であったので, 酵素-重量法とSouthgate法で分画を試みたところ, 水溶性ヘミセルロースが多いことがわかった。また, 大麦DF各画分の構成糖の分析も行った。

https://www.jstage.jst.go.jp/article/jsnfs1983/41/1/41_1_43/_pdf

Fumie Tsuchihashi

Papers

Effect of viscous indigestible polysaccharides on pancreatic-biliary secretion and digestive organs in rats

Effect of Barley on Development of Experimental Diabetes in Rats.

Changes in Lipid Components in Liver and Serum and Production of Lipid Peroxide in Liver by Organochlorine Pesticides in Rats

Determination of total dietary fiber in foods and food products by the enzymatic-gravimetric method.

Problems and modifications of the neutral detergent method and enzymatic-gravimetric method for determination of total dietary fiber.