Cholesterol fiber

There has been much publicity about fiber in the diet reducing cholesterol. Fiber does bind cholesterol, and it certainly causes some decrease in tlie amount in the blood. The reduction, expressed as a percentage, is higher in cases in which the original level of cholesterol is higher. There is, however, no definitive evidence that lowering cholesterol via the ingestion of fiber results in less heart disease. 

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. 

In our study, consumption of rye bread or rye bread with phloem did not have an effect on serum lipids (total, LDL or HDL cholesterol or triglycerides) (Table 14.4). This is contrary to a recent finding suggesting that soluble fiber from rye bread decreased the concentrations of cholesterol (Leinonen et al., 2000). In that study ingestion of rye bread (220 g/d) with naturally high amounts of insoluble (18 g/d) and soluble fiber (4 g/d) decreased the LDL concentrations by 8% in hypercholesterolemic men. The researchers speculated that soluble fiber, maybe P-glucan, was responsible for the hypocholesterolemic effect. The amount of rye bread (70 g/d vs 220 g/d), the amount of total (5.9-11.8 g/d vs 22.1 g/d) and soluble fiber (0.6-1.3 g/d vs 4 g/d) ingested in this study was considerably less, and could explain the lack of effects on blood lipids in our study. 

BROWN L, ROSNER B, wiLLET w w, SACKS F M (1999) Cholesterol-loweiing effeects of dietary fiber a meta-analysis, American Journal of Clinical Nutrition, 69, 30-42. 

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. 

Therapeutic lifestyle changes should be the first approach tried in all patients (Table 9—7).3 An adequate trial of TLC should be employed in all patients, but pharmacotherapy should be instituted concurrently in higher-risk patients. This includes dietary restrictions of cholesterol and saturated fats as well as regular exercise and weight reduction. In addition, therapeutic options to enhance LDL cholesterol lowering such as consumption of plant stanols/sterols (which competitively inhibit incorporation of cholesterol into micelles) and dietary fiber should be encouraged. These therapeutic options collectively may reduce LDL cholesterol by 20% to 25%. 

Therapeutic lifestyle changes should be continued and intensified (consider adding plant sterols/stanols and increase fiber) after 6 weeks if not below LDL cholesterol target. For those patients above their LDL cholesterol target after adequate trial of TLC (12 to 18 weeks), pharmacotherapy should be strongly considered. 

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. 

Trettnak W., Wolfbeis O.S., Fiber optic cholesterol biosensor with an oxygen optrode as the transducer Anal. Biochem. 1990 184 124. 

Martin-Carron N, Goni I, Larrauri JA, Garcia-Alonso A and Saura-Calixto F. 1999. Reduction in serum total and LDL cholesterol concentrations by a dietary fiber and polyphenol-rich grape products in hypercholesterolemic rats. Nutr Res 19 1371-1381. 

Leontowicz M, Gorinstein S, Bartnikowska E, Leontowicz H, Kulasek G and Trakhtenberg S. 2001. Sugar beet pulp and apple pomace dietary fibers improve lipid metabolism in rats fed cholesterol. Food Chem... 

Monounsaturated fat Carbohydrates Cholesterol Dietary fiber Plant sterols Protein Total calories... 

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). 

Experimental. A second study was conducted with nine postmenopausal women age 51-65 yr. The subjects were fed standardized meals for 19 weeks. The mean composition for the 7-day menus of natural foods as % of total calories was 15% protein, 50% carbohydrate, 35% fat with a P/S ratio of 0.7, 10 g/day crude fiber, and less than 300 mg/day cholesterol. In addition, the diets supplied 1289 mg calcium, 1832 mg phosphorus, 2561 mg sodium and 5099 mg potassium daily. The diets met the RDA for all other nutrients. Calorie levels were adjusted to maintain body weight. The experimental meals were fed during the last six weeks of this 19-week period. No more than one liquid meal was consumed by each subject in one week. Fasting and postprandial samples of blood and urine were collected as in the previous study. Diuresis was induced by scheduled consumption of water. 

In the studies discussed, wheat bran, cellulose, and psyllium fiber feeding resulted in increased fecal fat losses and in lowered blood serum cholesterol and triglyceride levels (14,15,32,41) as well as increased fecal losses of calcium. Possible involvement of dietary fat with high or low dietary fiber intake has not been extensively investigated. However, that calcium is involved in intestinal fat absorption is generally accepted (42-45). 

Self-selected, 40% or less calories from fat < 10 g fiber > 500 g cholesterol 1462a 498a 762a 52. la 47.9a 202a... 

Controlled, 30% calories from fat, 30 g fiber, < 50 g cholesterol 1440a 425b 995a 69. lb 30.9b 21b... 

These results apparently support those in the previous study however, because dietary fiber was higher in the low fat diet than in the high fat diet, it is impossible to separate the effects of fat, fiber and possibly cholesterol. The alterations used in the low fat, controlled diet were essentially those recommended in the U.S. Dietary Goals/Guidelines while the moderately high fat, self-selected diets resembled usual American dietary intake patterns. 

Furthermore, addition of lysine to soy protein markedly increased the rate of lipid absorption and addition of arginine to casein slowed lipid absorption. The slowed absorption of lipids in animals fed soy protein is similar to that reported for soluble fibers such as pectin and guar gum that act to lower serum cholesterol concentrations in a number of animal species, including humans. 

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