Cholesterol levels dietary control

What can be done to prevent atherosclerosis For persons with a high LDL level there is little doubt that a decreased dietary intake of cholesterol and a decrease in caloric intake are helpful. While such dietary restriction may be beneficial to the entire population, controlled studies of the effect of dietary modification on atherosclerosis have been disappointing and confusing.33 A diet that is unhealthy for some may be healthy for others. For example, an 88-year old man who ate 25 eggs a day for many years had a normal plasma cholesterol level of 150-200 mg / deciliter (3.9-5.2 mM) bb Comparisons of diets rich in unsaturated fatty acids, palmitic acid, or stearic acid have also been confusing.cc cd/dd Can it be true that palmitic acid from tropical oils and other plant sources promotes atherogenesis, but that both unsaturated fatty acids and stearic acid from animal fats are less dangerous ... 

In studying results from both chickens and man, Fisher et al. (67) concluded that pectin has a hypocholesterolemic effect only when fed with dietary cholesterol. On cholesterol-free diets, plasma cholesterol is not affected by dietary pectin. Subjects fed pectin with a cholesterol-containing diet had plasma cholesterol levels that were lower relative to those of subjects on the cholesterol control diet, but not relative to those of subjects on a cholesterol-free control diet. 

Curcumin has been proved to be an effective hypolipidaemic agent (Babu and Srinivasan, 1997). One study validated the role of dietary curcumin in maintaining healthy serum cholesterol levels in diabetic rats. Employing a high-cholesterol diet for the diabetic rats, curcumin exhibited a lowering of cholesterol and phospholipid in treated animals as compared with curcumin-free controls. Liver cholesterol, triglycerides and phospholipid elevated under diabetic conditions were lowered by dietary curcumin. Curcumin induces a... 

There have been three primary and eight secondary prevention trials in which dietary change was the only variable. Dietary modification included reduction in total fat, substitution of saturated fat by polyunsaturated oils and reduction in cholesterol intake. These changes resulted in a reduction of saturated fat intake by 27 55% and reductions in plasma cholesterol of up to 18%. However, with the exception of one study, the Lyon Diet Heart Study (de Lorgeril et al., 1994), neither total or CHD mortality was lowered significantly by the dietary interventions (Ravnskov, 1998 Parodi, 2004). In the successful Lyon Diet Heart Study, a Mediterranean-type diet was compared with the usual post-infarct prudent diet. Throughout this trial, plasma cholesterol levels were similar in both the treatment and control groups. 

Most experts recommend a food-based dietary approach to lower plasma cholesterol levels. Indeed, the FDA begins all claims about the role of diet and heart disease with ...a diet low in saturated fat and cholesterol.... Such a diet normally would include many vegetables, fruits, and limits on animal products and can also include 25 g of soy protein along with 3 to 6 g of soluble fiber. However, the role of such advice should be evaluated in terms of compliance with the advice as well as the potential efficacy of the recommended nutrition changes. The experimental evidence supporting dietary approaches to lower plasma LDL-C concentrations comes from controlled feeding trials devoid of many practical barriers that are likely to reduce the effectiveness of prescribed diets in real-life sitnations. Farther, the efficacy of recommended diets depends on compliance and the extent that... 

The primary mechanism by which lecithin lowers cholesterol is by decreasing the absorption of dietary cholesterol from the intestine to the blood stream (269, 270). There is also evidence that lecithin intake lowers cholesterol by increasing the amount of cholesterol used in the production of bile salts (271). As more cholesterol is used for bile salt synthesis, less is available to reach the blood stream and damage blood vessels. Lecithin also contributes polyunsaturated fatty acids to the diet, which may help control blood cholesterol levels. 

The interruption of enterohepatic recirculation of bile acids by the resins effectively lowers plasma cholesterol levels since cholesterol must now be diverted to de novo synthesis of bile acids. In addition, intestinal absorption of dietary cholesterol, normally facilitated by bile acids, is also reduced due to their excretion. Two significant compensatory mechanisms are called into action increased activity of hydroxymethylglutaryl coenzyme A reductase (HMG CoA reductase), which is the rate-controlling enzyme in the hepatic synthesis of cholesterol (see Fig. 11-4 and discussion to follow), and an increase in the number of LDL receptors. The latter mechanism offered the first meaningful treatment of heterozygous FH. Homozygous FH patients lacking LDL receptors, of course, do not respond. 

HMG-CoA reductase is also subject to translational control by a mevalonate-derived non-sterol regulator (D. Peffley, 1985 M. Nakanishi, 1988). Tliis component of the regulatory mechanism can be observed only when cultured cells are acutely incubated with statins, which block mevalonate formation. Under those conditions, sterols have no effect on HMG-CoA reductase mRNA translation however, mevalonate reduces the HMG-CoA mRNA translation by 80% with no change in mRNA levels. Translational control of hepatic HMG-CoA reductase by dietary cholesterol was shown in an animal model in which polysome-associated HMG-CoA reductase mRNA was analyzed in cholesterol-fed rats (C.M. Chambers, 1997). It was found that cholesterol feeding increased the portion of mRNA associated with translationally inactive monosomes and decreased the portion of mRNA associated with translationally active polysomes. The mechanism of HMG-CoA reductase translational control has not been elucidated. 

Because Ann Jeina continued to experience intermittent chest pain, in spite of good control of her hypertension and a 20-lb weight loss, her physician decided that a 2-drug regimen to lower her blood LDL cholesterol level must be added to the dietary measures aheady in place. Consequently, treatment with cholestyramine, a resin that binds some of the bile salts in the intestinal lumen, and the HMG-CoA reductase inhibitor pravastatin was initiated. 

Ans. The major fraction of the cholesterol in the blood is synthesized in the liver. Decreasing dietary cholesterol has some effect in decreasing the cholesterol level in the blood. The effect is measurable but not huge unless the person s normal diet contains excessive animal fat. However, dietary control is prudent for most people since any decrease in blood cholesterol level decreases the tendency for plaque formation. 

Olive oil is a good example of a lipid that provides numerous health benefits when included in the diet. The main type of lipid found in all types of olive oil is monounsaturated fatty acids, or MUFAs, with the 18-carbon oleic acid being the predominant component (see Table 8.1 for its formula). MUFAs are considered to be healthy lipids. There is evidence that dietary MUFAs help lower total cholesterol levels in the body, and especially the levels of undesirable low-density lipoproteins (LDLs). Some research results show that MUFAs may help maintain normal blood clotting and normal blood pressure and may aid in the control of blood sugar levels. 

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