Bile acids fiber

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

Dietary fiber and fiber-rich food fractions bind bile acids and bile salts in vitro. This interaction is more pronounced for the lignin component. 

OILE ACID SEQUESTRANTS. Fhtients taking the antihyperlipidemic dragp, particularly the bile acid sequestrants, may experience constipation. The dragp can produce or severely worsen preexisting constipation. The nurse instructs the patient to increase fluid intake, eat foods high in dietary fiber, and exercise daily to help prevent constipation. If the problem persists or becomes... 

Explains possible need for vitamin A and D therapy and high-fiber foods if patient is receiving bile acid sequestrant. 

Various mechanisms have been proposed to explain the hypocholesterolemic effect of GA (Annison et al., 1995 Tiss et al., 2001). Some studies have suggested that the viscosity of fermentable dietary fiber contributes substantially to the reduction of lipids in animals and humans (Gallaher et al., 1993 Moundras et al., 1994). However, other studies suggested that this property is not related to plasma lipids (Evans et al., 1992). The mechanism involved is clearly linked to increased bile acid excretion and fecal neutral sterol or a modification of digestion and absorption of lipids (Moundras et al., 1994). 

NORMAND F L, ORY R L, MOD R R (1987) Binding of bile acids and trace minerals by soluble hemicelluloses of rice The ability of rice fiber components to bind bile acids may play a role in lowering serum cholesterol. Food Technology, 41(2) 86-90. 

Similarly, dietary fibers are known to interact with bile acids in the intestinal limien and thus increase bile salt excretion in feces, resulting in decreased munbers... 

Pectin, the substance that makes jellies and jams so jelly-like, can help lower blood cholesterol levels by forcing the body to make more bile acids. Pectin is a type of fiber, and like most fiber, pectin cannot be digested by the human body. Instead, the fiber moves slowly through the small intestines. When pectin encounters sugar and acid, its molecules trap water within its long chains, turning into a gel-like mass. This gel traps and eventually eliminates bile acids from the gut. When this happens, the body must make more bile acids, reducing the amount of cholesterol in the blood. 

Increased intake of soluble fiber in the form of oat bran, pectins, certain gums, and psyllium products can result in useful adjunctive reductions in total and LDL cholesterol (5% to 20%), but these dietary alterations or supplements should not be substituted for more active forms of treatment. They have little or no effect on HDL-C or triglyceride concentrations. These products may also be useful in managing constipation associated with the bile acid resins (BARs). 

Bile acids and salts have been found to enhance the absorption of both calcium and vitamin D hence, to increase calcium absorption both directly and indirectly (3,37). However, the ability of some dietary fibers such as lignin and pectin to absorb conjugated and deconjugated bile salts onto their surfaces to be excreted in the feces (a mechanism credited to the hypocholesterolemic effect of some dietary fibers) may result in an overall decrease in calcium absorption from the gastrointestinal tract (7,33,38-40). 

The mechanisms by which various forms of dietary fiber influence calcium bioavailability apparently also differ. In some cases, apparent dietary fiber effects on calcium bioavailability may be secondary to effects on bile acid and salt secretion and reabsorption or to other dietary components. 

A high fiber diet will help by redirecting fat soluble metabolites to the colon rather than bladder. THC is eliminated primarily in the stool via bile acids. Both EMIT and RIA detect a secondary metabolite which is reabsorbed from the intestines. Thus a person with a high fiber diet will excrete a majority of THC [metabolites] in the stool [Anonlj. A fiber-based laxitive will also help by binding bile-acids. Use caution. Fiber laxitives can alter one s bowel schedule and lead to dependancy. 

B. Sundberg, P. Aman, and H. Anders- HV083 son. Oat beta-glucan increases bile acid excretion and a fiber-rich barley fraction increases cholesterol excretion in ileostomy subjects. Amer J Clin HV084... 

Bile acid synthesis stimulation. Fiber, administered in ration of male rats at a dose of 5% of the diet, produced a higher total bile acid pool size compared to rats fed cellulose. It also lowered the hydrophobicity of the bile acid pool """. 

Fecal steroid and lipid excretion. Fiber supplements from sugar cane residue (bagasse), administered to volunteers for 12 weeks, increased stool weights and stool fat excretion. Bagasse increased the daily loss of acid steroids and decreased transit time without alteration in fecal flora. The increased excretion of bile acids and fatty acids failed to lower the plasma cholesterol and TGs after 12 weeks ". 

A. Southgate. The effects of two di- SO084 etary fiber supplements on gastrointestinal transit, stool weight and frequency, and bacterial flora, and fecal bile acids in normal subjects. Me- SO085 tabolism 1977 26(2) 117-128. 

Bile salts secreted into the intestine are efficiently reabsorbed (greater than 95 percent) and reused. The mixture of primary and secondary bile acids and bile salts is absorbed primarily in the ileum. They are actively transported from the intestinal mucosal cells into the portal blood, and are efficiently removed by the liver parenchymal cells. [Note Bile acids are hydrophobic and require a carrier in the portal blood. Albumin carries them in a noncovalent complex, just as it transports fatty acids in blood (see p. 179).] The liver converts both primary and secondary bile acids into bile salts by conjugation with glycine or taurine, and secretes them into the bile. The continuous process of secretion of bile salts into the bile, their passage through the duodenum where some are converted to bile acids, and their subsequent return to the liver as a mixture of bile acids and salts is termed the enterohepatic circulation (see Figure 18.11). Between 15 and 30 g of bile salts are secreted from the liver into the duodenum each day, yet only about 0.5 g is lost daily in the feces. Approximately 0.5 g per day is synthesized from cholesterol in the liver to replace the lost bile acids. Bile acid sequestrants, such as cholestyramine,2 bind bile acids in the gut, prevent their reabsorption, and so promote their excretion. They are used in the treatment of hypercholesterolemia because the removal of bile acids relieves the inhibition on bile acid synthesis in the liver, thereby diverting additional cholesterol into that pathway. [Note Dietary fiber also binds bile acids and increases their excretion.]... 

Dietary fiber has a pronounced effect on the characteristics of the fecal mass and on the rate of passage of digest through the G1 trad, High fiber diets also play a role in the excretion of bile acids and cholesterol. 

Despite these variables, it appears that the primary attribute of soluble fibers that inhibit cholesterol absorption is the ability to form a viscous matrix when hydrated. Many water-soluble fibers become viscous in the small intestine (Eastwood and Morris, 1992). It is believed that increased viscosity impedes the movement of cholesterol, bile acids, and other lipids and hinders micelle formation, thus reducing cholesterol absorption and promoting cholesterol excretion from the body. Consumption of viscous fibers was shown to increase the thickness of the unstirred water layer in humans (Flourie et al., 1984 Johnson and Gee, 1981) and reduce the amount of cholesterol appearing in the lymph of cannulated rats (Ikeda et al., 1989b Vahouny et al., 1988). Turley et al. (1991, 1994) reported that... 

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