Digestion and absorption

Malabsorption Because they sequester bile acids, these resins may interfere with normal fat absorption and digestion and may prevent absorption of fat-soluble vitamins such as A, D, E, and K. 

An intact functional GIT is essential for complete absorption and digestion of nutrients. Short bowel syndrome (SBS) is a disease state imposed by significant resection of the small bowel, which results in the malabsorption of nutrients and fluids. Morbidity and mortality due to gastrointestinal failure in SBS patients has been improved by interventional nutrition with PN and EN. The goal of nutritional... 

Most general EN formulas contain an equal balance of nonprotein energy between carbohydrate and fat. Elemental or chemically defined products are the exception because they are intended to be high-carbohydrate, low-fat formulas to enhance absorption and digestion. In pulmonary patients administration of a high-carbohydrate formula... 

Following is the structural formula of cholic acid (Section 19.4A), a component of human bile whose function is to aid in the absorption and digestion of dietary fats ... 

Figure 19.10 shows a structural formula for cholic acid, a constituent of human bile. The molecule is shown as an anion, because it would be ionized in bile and intestinal fluids. Bile acids, or, more properly, bile salts, are synthesized in the liver, stored in the gallbladder, and secreted into the intestine, where their function is to emulsify dietary fats and thereby aid in their absorption and digestion. Furthermore, bile salts are the end products of the metabolism of cholesterol and, thus, are a principal pathway for the elimination of that substance from the body. A characteristic structural feature of bile salts is a cis fusion of rings A/B. 

Williamson G. Possible effects of dietary polyphenols on sugar absorption and digestion. Mol Nutr Food Res. 2013 57(11 48-57. 

The main bile adds are cholic acid and chenodeoxycholic acid (3-126). These acids are excreted from the liver as glycine salts or taurine conjugates (see Section 5.15) into the gallbladder and then into the small intestine. In the duodenum, bile adds act as emulsifiers in the absorption and digestion of fats and fat soluble vitamins. 

Raw foods were freeze-dried and analyzed for carbon isotopes using mass spectrometry. Cooked foods were prepared following historic recipes, then were freeze-dried prior to analysis. For the trace element analysis, foods (both raw and cooked) were wet ashed using nitric acid in Teflon lined pressure vessels and digested in a CEM Microwave oven. Analysis of Sr, Zn, Fe, Ca and Mg was performed using Atomic Absorption Spectrometry in the Department of Geology, University of Calgary. 

Although products of fat digestion, including cholesterol, are absorbed in the first 100 cm of small intestine, the primary and secondary bile acids are absorbed almost exclusively in the ileum, and 98—99% are returned to the liver via the portal circulation. This is known as the enterohepatic circulation (Figure 26—6). However, lithocholic acid, because of its insolubility, is not reabsorbed to any significant extent. Only a small fraction of the bile salts escapes absorption and is therefore eliminated in the feces. Nonetheless, this represents a major pathway for the elimination of cholesterol. Each day the small pool of bile acids (about 3-5 g) is cycled through the intestine six to ten times and an amount of bile acid equivalent to that lost in the feces is synthesized from cholesterol, so that a pool of bile acids of constant size is maintained. This is accomplished by a system of feedback controls. 

The chapters on integration of metabolism, nutrition, digestion and absorption, and vitamins and minerals have been completely re-written. 

MiCHAELSEN s, OTTE J, SIMONSEN L-0 and SORENSEN H (1994) Absorption and degradation of individual intact glucosinolates in the digestive tract of rodents , Acta Agric. Scand. Sect. A. Animal Sci., 44 25-37. 

All the actual or putative functional benefits of carotenoids are dependent on their bioavailability amounts consumed, amounts released from the food structure during digestion and extent of absorption and tissue distribution. The following three sections deal with each of these issues in turn. 

MORAis M B, FESTE A, MILLER R G, LiFSCHiTZ c H (1996) Effect of resistant and digestible starch on intestinal absorption of calcium, iron, and zinc in infant pigs. Pediatr Res. 39 872-6. 

Ferruzzi, M.G. and Blakeslee, J., Digestion, absorption and cancer preventative activity of dietary chlorophyll derivatives, Nutr. Res., 21, 1, 2007. 

In this model, no attempt is made to reproduce the in vivo physiochemical conditions occurring in the lumen of the human small intestine during digestion. This cell culture model only provides information about the intestinal absorption and metabolism processes of the compound. Using this cell culture system in con-... 

The growth of ectomycorrhizal trees is frequently improved by their increased phosphorus (P) accumulation (3), and this, in turn, is related to the intensity of the mycorrhizal infection. Ectomycorrhizal fungi solubilize insoluble forms of A1 and Ca phosphates as well as inositol hexaphosphates, though a wide interstrain variability has been recorded (112). These complex P forms are digested by the secretion of extracellular acid and alkaline phosphomono- and phosphodi-ester-ases. Pi in soil solutions is easily taken up by ectomycorrhizal hyphae and then translocated to the host roots. Its absorption and efflux are probably regulated... 

The food, now in a liquid form known as chyme, passes through the pyloric sphincter into the duodenum, where stomach acid is neutralized. There is wide variation in lengths of the components of the small intestine (i.e., duodenum, jejunum, and ileum) between individuals (Table 98-1). Most absorption of digested carbohydrate and protein occurs within the jejunum. Most fat absorption occurs within the jejunum and ileum. In the small bowel, breakdown of macronutrients (i.e., carbohydrate, protein, and fat) occurs both within the lumen of the gut and at the intestinal mucosal membrane surface. The absorptive units on the intestinal mucosal membrane are infoldings known as... 

Food-control laboratories seeking to be accredited for the purposes of the Directive should include, as a minimum, the following techniques in generic protocols HPLC, GC, atomic absorption and/or ICP (and microscopy). A further protocol on sample preparation procedures (including digestion and solvent dissolution procedures) should also be developed. Other protocols for generic methods which are acceptable to UKAS may also be developed. Proximate analyses should be addressed as a series of specific methods including moisture, fat, protein and ash determinations. 

Sarr MG, Kelly KA, Phillips SF. Canine jejunal absorption and transit during interdigestive and digestive motor states. Am J Physiol 1980 239 G167-G172. 

The liver is an organ of more than average interest to biochemists its functions are intimately related to digestion, absorption, and metabolism. It varies in shape like other internal organs (Fig. 6), and... 

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