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Digestion of lipids

A and B are in cis position relative to each other (see p. 54). One to three hydroxyl groups (in a position) are found in the steroid core at positions 3, 7, and 12. Bile acids keep bile cholesterol in a soluble state as micelles and promote the digestion of lipids in the intestine (see p.270). Cholic add and cheno-deoxychoMc acid are primary bile acids that are formed by the liver. Their dehydroxylation at C-7 by microorganisms from the intestinal flora gives rise to the secondary bile acids lithocholic acid and deoxycholic acid. [Pg.56]

Ultracet 5.1 (0.2) 5.6 (0.2) A pancreatic enzyme that is involved in the digestion of lipids, proteins, and carbohydrates. [Pg.58]

Mun, S., Decker, E.A., McClements, D.J. (2007). Influence of emulsifier type on in vitro digestibility of lipid droplets by pancreatic lipase. Food Research International, 40, 770-781. [Pg.75]

In another set of studies, it has been reported that the in vitro digestibility of lipid droplets by pancreatic lipase is significantly affected by emulsifier type (Mun et al, 2006, 2007 Park et al., 2007). Intuitively, one might expect that a thick dense layer of strongly bound protein-polysaccharide complex at the oil-water interface would reduce considerably the in vivo accessibility of lipases, and hence would reduce the rate of human metabolism of fats. Establishment of the validity of this hypothesis must still await consolidation of a substantial body of detailed results from independent systematic studies on a broad range of mixed biopolymer systems. [Pg.343]

Multicomponent starchy foods such as cereals also become more digestible after irradiation, but noncarbohydrate components, particularly vitamins, undergo decomposition.230 However, another report shows that the in vivo digestibility of starch in irradiated food is decreased, along with some other side effects (such as reduced digestibility of lipids and proteins), after 8 months of feeding.231... [Pg.292]

In addition to bile salts, which facilitate the digestion of lipids, five major classes of steroid hormones are derived from cholesterol progestagens, glucocorticoids, mineralocorticoids, androgens, and estrogens. Hydroxylations by P450 monooxygenases that use NADPH and O2 play an important role in the synthesis of steroid hormones and bile salts from... [Pg.1095]

Bile Salts Enable the Digestion of Lipids Cholesterol is the precursor of both steroids and bile salts and is an integral component of cell membranes. It is eliminated from the body via conversion to bile salts and direct secretion into the bile. In fact, the word cholesterol (from the Greek chole (bile) and stereos (solid)) was used originally to describe the material of which gallstones are made. In the process of degradation, it is converted to the primary bile acids cholic acid and chenodeoxycholic acid in approximately equal amounts. The salts of these acids are excreted in bile. They perform two important functions in the digestive tract ... [Pg.1550]

Figure 4. Emulsification and digestion of lipids, leading to accumulation of micelles and vesicles (Rigler et al., 1986) reproduced with permission. Figure 4. Emulsification and digestion of lipids, leading to accumulation of micelles and vesicles (Rigler et al., 1986) reproduced with permission.
Bile acids The major metabolites of cholesterol, which are synthesized in the liver and stored in the gallbladder for use as emulsifiers in the digestion of lipids. Primary bile acids are those synthesized directly from cholesterol in the liver Secondary bile acids are metabolites of primary bile acids produced by the action of intestinal bacteria. [Pg.304]

Steroids are a naturally occurring family of organic molecules of biochemical and medical interest. A great deal of controversy has surrounded various steroids. We worry about the amount of cholesterol in the diet and the possible health effects. We are concerned about the use of anabolic steroids by athletes wishing to build muscle mass and improve their performance. However, members of this family of molecules derived from cholesterol have many important functions in the body. The bile salts that aid in the emulsification and digestion of lipids are steroid molecules, as are the sex hormones testosterone and estrone. [Pg.534]

Beyond its physiologic role in the intestinal digestion of lipids and lipid-soluble vitamins, the bUe also plays an important role in the excretion of xenobio-tics, including drugs and their metabolites. This includes a diverse array of compounds, both polar and lipophilic, including, anions, cations, and neutral molecules. In humans, the molecular threshold is approximately 500 to 600, with renal excretion being the primary route of excretion for smaller molecules. [Pg.188]

After cholesterol is formed, it can be converted to other steroids of widely varying physiological function. The smooth ER is an important site for both the synthesis of cholesterol and its conversion to other steroids. Most of the cholesterol formed in the liver, which is the principal site of cholesterol synthesis in mammals, is converted to bile acids, such as cholate and glycocholate (Figure 21.30). These compounds aid in the digestion of lipid droplets by emulsifying them and rendering them more accessible to enzymatic attack. [Pg.633]

The liver has many functions and is critical to metabolism. The liver produces bile, consisting of bile salts and other chemicals, which is required for the digestion of lipids. The liver is also responsible for the conversion of waste products from protein metabolism into urea, which is eliminated in the urine. [Pg.559]

The functions of bile acid conjugates within the small intestine during lipid absorption have been studied extensively (Senior, 1964 Hofmann and Small, 1967). The bile salts are utilized to emulsify lipids, to facilitate digestion of lipids, and to maintain the products of digestion in micellar suspension. Hence, they have a central role in the absorption of fat and lipid-soluble substances such as vitamin D, vitamin K, and carotene. [Pg.100]


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Lipid digestion

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