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Journal of the Science of Food and... May 2016The human digestive system is reviewed in the context of a process with four major unit operations: oral processing to reduce particle size and produce a bolus; gastric... (Review)
Review
The human digestive system is reviewed in the context of a process with four major unit operations: oral processing to reduce particle size and produce a bolus; gastric processing to initiate chemical and enzymatic breakdown; small intestinal processing to break down macromolecules and absorb nutrients; and fermentation and water removal in the colon. Topics are highlighted about which we need to know more, including effects of aging and dentition on particle size in the bolus, effects of different patterns of food and beverage intake on nutrition, changes in saliva production and composition, mechanical effects of gastric processing, distribution of pH in the stomach, physicochemical and enzymatic effects on nutrient availability and uptake in the small intestine, and the composition, effects of and changes in the microbiota of the colon. Current topics of interest including food synergy, gut-brain interactions, nutritional phenotype and digestion in the elderly are considered. Finally, opportunities for food design based on an understanding of digestive processing are discussed.
Topics: Aging; Digestion; Food Analysis; Gastrointestinal Tract; Humans; Nutritional Physiological Phenomena
PubMed: 26711173
DOI: 10.1002/jsfa.7601 -
Cell and Tissue Research Sep 2019Living cells depend on a constant supply of energy-rich organic molecules from the environment. Small molecules pass into the interior of the cell via simple diffusion...
Living cells depend on a constant supply of energy-rich organic molecules from the environment. Small molecules pass into the interior of the cell via simple diffusion or active transport carried out by membrane bound transporters; macromolecules, or entire cells, are taken up by endocytosis/phagocytosis, and are degraded intracellularly in specialized membrane bound compartments (lysosomes). Whereas all cells are capable of transporting molecules through the membrane, the efficient procurement, digestion and uptake of nutrients have become the function of specialized cell types and organs, forming the digestive system in multicellular animals. In mammals, for example, the digestive system is comprised of glandular organs with classes of cells specialized in the secretion of enzymes for the extracellular digestion of food particles (e.g., exocrine cells of the salivary gland, pancreas), as well as other organs with absorptive function (e.g., small intestine). Numerous other cell types, such as smooth muscle cells, neurons and enteroendocrine cells, are associated with glandular cells and intestinal cells to promote the digestive process.
Topics: Animals; Biological Evolution; Digestion; Digestive System; Immune System; Phagocytosis
PubMed: 31478136
DOI: 10.1007/s00441-019-03102-x -
British Journal of Nursing (Mark Allen...This article, the second in the nutrition series, presents an outline of food chemistry and the digestion of energy-producing foods. It is hoped that this will... (Review)
Review
This article, the second in the nutrition series, presents an outline of food chemistry and the digestion of energy-producing foods. It is hoped that this will facilitate understanding of some of the principles of nutrition. A number of 'clinical points' are highlighted to emphasize the link between theory and practice. The processes by which the chemical building blocks (carbon, oxygen, hydrogen and nitrogen) are formed into more complex molecules such as proteins, carbohydrates and fats are explained. The gross anatomy of the digestive system is outlined and the sites where digestive enzymes are secreted are identified. Regulation of the digestive system by endocrine secretions and the nervous system is described and tabulated.
Topics: Carbohydrate Metabolism; Digestion; Digestive System; Digestive System Physiological Phenomena; Fats; Gastrointestinal Hormones; Humans; Proteins
PubMed: 9470654
DOI: 10.12968/bjon.1997.6.22.1285 -
Biomedicine & Pharmacotherapy =... Jan 2007This paper reviews the in vitro digestion models developed to assess the stability digestion of food allergens, as well as the factors derived from the methodology and... (Review)
Review
This paper reviews the in vitro digestion models developed to assess the stability digestion of food allergens, as well as the factors derived from the methodology and food structure that may affect the assay results. The adequacy of using the digestion stability of food allergens as a criterion for assessing potential allergenicity is also discussed. Data based on the traditional pepsin digestibility test in simulated gastric fluid are discussed in detail, with special attention to the influence of the pH and pepsin: allergen ratio in the pepsinolysis rate. This review points out the importance of using physiologically relevant in vitro digestion systems for evaluating digestibility of allergens. This would imply the sequential use of digestive enzymes in physiological concentrations, simulation of the stomach/small intestine environment (multi-phase models) with addition of surfactants such as phospholipids or bile salts, as well as the consideration of the gastrointestinal transit and the effect of the food matrices on the allergen digestion and subsequent absorption through the intestinal mucosa. In vitro gastrointestinal digestion protocols should be preferably combined with immunological assays in order to elucidate the role of large digestion-resistant fragments and the influence of the food matrix on the stimulation of the immune system.
Topics: Allergens; Digestion; Digestive System; Humans; Hypersensitivity; Intestinal Absorption; Models, Biological
PubMed: 17188456
DOI: 10.1016/j.biopha.2006.10.005 -
Neurogastroenterology and Motility Mar 2006Gastroduodenal physiology is traditionally understood in terms of motor-secretory functions and their electrical, neural and hormonal controls. In contrast, the... (Review)
Review
Gastroduodenal physiology is traditionally understood in terms of motor-secretory functions and their electrical, neural and hormonal controls. In contrast, the fluid-mechanical functions that retain and disperse particles, expose substrate to enzymes, or replenish the epithelial boundary with nutrients are little studied. Current ultrasound and magnetic resonance imaging allows to visualize processes critical to digestion like mixing, dilution, swelling, dispersion and elution. Methodological advances in fluid mechanics allow to numerically analyse the forces promoting digestion. Pressure and flow fields, the shear stresses dispersing particles or the effectiveness of bolus mixing can be computed using information on boundary movements and on the luminal contents. These technological advances promise many additional insights into the mechanical processes that promote digestion and absorption.
Topics: Animals; Diagnostic Imaging; Diagnostic Techniques, Digestive System; Digestion; Duodenum; Gastrointestinal Motility; Humans; Models, Biological; Stomach
PubMed: 16487408
DOI: 10.1111/j.1365-2982.2006.00759.x -
Bioengineered Dec 2021Digestive systems in human, animals, and fish are biological reactors and membranes to digest food and extract nutrients. Therefore, static and dynamic models of... (Review)
Review
Digestive systems in human, animals, and fish are biological reactors and membranes to digest food and extract nutrients. Therefore, static and dynamic models of digestion systems are developed to study e.g. novel food and feed before studies. Such models are well developed for human, but not to the same extent for animals and fish. On the other hand, recent advances in aquaculture nutrition have created several potential fish meal replacements, and the assessment of their nutrient digestibility is critical in the application as a fish meal replacement. Using an method, the assessment of an ingredient digestibility could be faster and less expensive compared to using an experiment. An method has been widely used to assess food nutrient digestibility for humans; however, its application for fish is still in the early stages. Both the human and fish as monogastric vertebrates share similar gastrointestinal systems; thus, the concept from the application for humans could be applied for fish. This review aims to improve the digestion protocol for fish by adapting the concept from then study for humans, summarizing the current available digestion model developed for human and fish digestion study, identifying challenges specifically for fish required to be tackled and suggesting an engineering approach to adapt the human gastrointestinal model to fish. Protocols to conduct digestion study for fish are then proposed.
Topics: Animal Feed; Animals; Aquaculture; Bioreactors; Digestion; Fishes; Gastrointestinal Tract; Humans; Models, Biological; Nutrients
PubMed: 34187302
DOI: 10.1080/21655979.2021.1940769 -
Complementary Medicine Research 2020Before the spleen was discovered to be a lymphatic blood organ, it had for centuries been considered to be a digestive organ. Concepts of a regulative, secretory and... (Review)
Review
BACKGROUND
Before the spleen was discovered to be a lymphatic blood organ, it had for centuries been considered to be a digestive organ. Concepts of a regulative, secretory and resorptive function in the digestive system were based mainly on a postulated connection between the stomach and the spleen. Splenogastric vascular connections have recently been rediscovered by modern surgery.
SUMMARY
To test the hypothesis that the spleen has a digestive function, this article reviews the literature focusing on the interaction between the spleen and the stomach. We examine the historical medical view of the spleen and stomach system and the reasons why a digestive function was abandoned in the 17th and 18th centuries. We then review the rediscovery of the splenogastric system and the present-day state of knowledge (anatomical origin, variability, haemodynamics) and present it in terms of the phylogenetic and embryological development of the spleen and stomach system. Key Message: Splenogastric arteries and gastrosplenic veins form a portal system which directly connects the spleen and stomach parenchyma. Despite its mesodermal anlage, phylogenetically and embryologically the spleen is intimately interconnected with the entodermal stomach parenchyma but detaches from this in the course of development. Further study is required to establish whether the splenogastric system is merely an evolutive remnant or actually a part of a functioning spleen-stomach system as postulated in complementary and integrative medicine.
Topics: Digestion; Humans; Phylogeny; Spleen; Stomach
PubMed: 32229731
DOI: 10.1159/000506390 -
Food Research International (Ottawa,... Jul 2022Two kinds of tofu with obvious differences in texture ["GDL" and "CaSO", standing for tofus made with the application of either glucono-δ-lactone (GDL) or calcium...
Two kinds of tofu with obvious differences in texture ["GDL" and "CaSO", standing for tofus made with the application of either glucono-δ-lactone (GDL) or calcium sulfate, with measured hardness 23.1 ± 3.3 g and 105.2 ± 25.1 g, respectively] were used as to investigate the in vitro progress and extent of tofu digestion, using an independently-developed artificial gastric digestion system (AGDS). The particle size distributions of both CaSO and GDL tofu shifted towards smaller particles as the digestion time increased, while the viscosity of the gastric digesta also increased. Tofu proteins were hydrolyzed in the simulated stomach, with GDL tofu showing a higher hydrolysis rate, based on the temporal evolution of SDS-PAGE bands, and had a higher amino acids accumulation than CaSO tofu at the end of gastric digestion. In the absence of peptic enzymes, the protein was acidically-hydrolyzed, but the degree of hydrolysis was much lower than in the presence of enzymes; these findings are in accord with the changes in microstructure observed by scanning electron microscopy. The results indicated that the in vitro extent of tofu digestion is related to its hardness, which is in turn related to its microstructure; they also indicated the potential of our developed in vitro dynamic stomach in studying semi-solid foods.
Topics: Digestion; Hardness; Soy Foods; Stomach; Viscosity
PubMed: 35761694
DOI: 10.1016/j.foodres.2022.111458 -
Clinical and Experimental Pharmacology... Oct 20091. The best characterized mammalian circadian rhythms follow a light-entrained central master pacemaker in the suprachiasmatic nucleus and are associated with... (Review)
Review
1. The best characterized mammalian circadian rhythms follow a light-entrained central master pacemaker in the suprachiasmatic nucleus and are associated with fluctuations in the activities of clock genes, including Clock, Bmal1, Per and Cry, the products of which bind to sequences in the promoters of effector genes. This is the central clock. 2. In the present review, we discuss evidence for an independent, but interacting, gut-associated circadian clock, the peripheral clock, which is entrained by food. 3. Disruption of circadian rhythms is associated with a wide range of pathologies, most prominently metabolism linked, but the effects of disruption of circadian rhythms on the digestive system are less well studied, although also likely to lead to functional consequences. There are clues suggestive of links between gastrointestinal disorders related to inflammation, cancer and motility and disruption of peripheral rhythms. Research aimed at understanding these links is still in its infancy. 4. We also discuss practical aspects of the presence of circadian rhythms in gastrointestinal tissues for researchers related to experimental design, data interpretation and the choice of animal models. 5. There is currently sufficient evidence to suggest that circadian rhythms are important to gut function, metabolism and mucosal defence and that further investigation will uncover connections between disordered rhythms and gastrointestinal malfunction.
Topics: Animals; Circadian Rhythm; Digestion; Digestive System Physiological Phenomena; Gastroenteritis; Gastrointestinal Motility; Gastrointestinal Tract; Humans; Immune System; Models, Biological; Time Factors
PubMed: 19566817
DOI: 10.1111/j.1440-1681.2009.05254.x -
Journal of Dairy Science Oct 1991Physical and chemical processing of feed ingredients and feeding management strategies are major instruments of manipulating amount and site of starch digestion in the... (Review)
Review
Physical and chemical processing of feed ingredients and feeding management strategies are major instruments of manipulating amount and site of starch digestion in the gastrointestinal tract. Generally, as rumen escape of starch increases, postruminal starch digestion increases, and there does not appear to be a limitation to intestinal starch digestion. However, the efficiency with which postruminal starch is digested decreases, which represents a limitation that warrants investigation. Even though digestible dietary starch is presented to the intestine, there is no net glucose absorption at the portal vein, and plasma glucose levels remain relatively unaffected. This result may be associated with the large metabolic requirement for postruminally absorbed glucose, which is preferentially used for oxidative metabolism at the visceral tissue level. In addition, peripheral glucose concentration is highly regulated. A possible implication is that the exogenous glucose supply may spare endogenously synthesized glucose for gut metabolism, allowing more to be directed to the mammary gland. Amino acids also may be spared (less metabolism of dietary and tissue amino acids in the gut). Current production studies yield no clear evidence as to the benefits of postruminal digestion of starch to enhance milk yield or to change its composition. However, studies suggest that starch digested postruminally is used more efficiently for milk synthesis than that digested in the rumen.
Topics: Animals; Cattle; Dietary Carbohydrates; Digestion; Digestive System Physiological Phenomena; Female; Intestine, Small; Lactation; Milk; Rumen; Starch
PubMed: 1744284
DOI: 10.3168/jds.S0022-0302(91)78552-4