cholesterol

(redirected from Clestral)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

cholesterol

 [ko-les´ter-ol]
a steroid alcohol found in animal fats and oils, bile, blood, brain tissue, milk, egg yolk, myelin sheaths of nerve fibers, liver, kidneys, and adrenal glands. It is a precursor of bile acids and steroid hormones, and it occurs in the most common type of gallstone, in atheroma of the arteries, in various cysts, and in carcinomatous tissue. Most of the body's cholesterol is synthesized by the liver, but some is obtained in the diet from animal-derived foods. Plant-derived foods are cholesterol-free. Cholesterol is not transported free in the blood but is bound to certain proteins to form lipoproteins. Two important fractions of the serum lipoproteins are high-density lipoproteins (HDL) and low-density lipoproteins (LDL).

High levels of total serum cholesterol have been shown to be associated with a high risk for coronary artery disease and myocardial infarction. Research has drawn a distinction between HDL-C, the cholesterol carried on high-density lipoproteins and LDL-C, the cholesterol carried on low-density lipoproteins. The balance between HDL-C and LDL-C is more significant than the total concentration of cholesterol in the blood. The risk of coronary heart disease increases as LDL-C increases and HDL-C decreases.

Because HDL-C promotes the removal of excess cholesterol from the cells and its excretion from the body, it is thought to be beneficial rather than harmful. In contrast, LDL-C picks up cholesterol from ingested fats and from cells that synthesize it in the body and delivers it to blood vessels and muscles where it is deposited in the cells. The concentration of cholesterol in cells within the linings of the arteries contributes to the build-up of atherosclerotic plaques. (See also atherosclerosis.)

A third type of lipoprotein is known as very-low-density lipoprotein (VLDL). There is a preponderance of triglyceride and very little cholesterol in VLDL. Triglyceride is the basic type of lipid used for the storage of energy. The role of serum triglyceride in the formation of atherosclerotic plaques is not known. Those persons who are at high risk for heart disease, already have a heart condition, or are obese should limit the amount of fats and cholesterol in the foods they eat. LDL-C levels can be reduced by limiting dietary intake of saturated fat and cholesterol. Organ meats and egg yolks are high in cholesterol. HDL-C levels can be raised by exercise, stopping cigarette smoking, and losing excess body fat.
Structure and metabolism of cholesterol. From Dorland's, 2000.
Blood Cholesterol. Laboratory testing of cholesterol in the blood is often used as a preliminary test for a disorder of blood lipids. Although the normal values for total blood cholesterol vary according to age, diet, and nationality, levels above 200 mg/dl indicate a need for further testing and efforts to reduce the cholesterol level. In general, as the total cholesterol level rises above 150 mg/dl, the risk for coronary artery disease gradually increases. Persons with cholesterol levels above 260 mg/dl may require medication to lower their LDL-C levels and reduce the risk of heart disease.

Increased levels of cholesterol in the blood are found in cardiovascular disease and atherosclerosis, obstructive jaundice, hypothyroidism, nephrosis, and uncontrolled diabetes mellitus. Cholesterol exists in both a free and esterified form; the ratio of free to esterified cholesterol is significant in the diagnosis of certain diseases. For example, there is a markedly abnormal ratio of these two forms of cholesterol in hepatic biliary disease, infectious diseases, and extreme cholesterolemia.

Decreased levels of cholesterol in the blood are noted when there is malabsorption of cholesterol from the intestinal tract as in pernicious anemia, hemolytic jaundice, hyperthyroidism, and terminal cancer.

cho·les·ter·ol

(kō-les'ter-ol),
5-cholesten-3β-ol (cholestane with a 5,6 double bond and a 3β-hydroxyl group); the most abundant steroid in animal tissues, especially in bile and gallstones, and present in food, especially food rich in animal fats; circulates in the plasma complexed to proteins of various densities and plays an important role in the pathogenesis of atheroma formation in arteries; a precursor of steroid hormones.
See also: lipoprotein.

cholesterol

/cho·les·ter·ol/ (kah-les´ter-ol) a eukaryotic sterol that in higher animals is the precursor of bile acids and steroid hormones and a key constituent of cell membranes. Most is synthesized by the liver and other tissues, but some is absorbed from dietary sources, with each kind transported in the plasma by specific lipoproteins. It can accumulate or deposit abnormally, as in some gallstones and in atheromas. Preparations are used as emulsfiers in pharmaceuticals.
Enlarge picture
Structure and metabolism of cholesterol.

HDL cholesterol , high-density–lipoprotein cholesterol (HDL-C) the serum cholesterol carried on high-density lipoproteins, approximately 20 to 30 per cent of the total.
LDL cholesterol , low-density–lipoprotein cholesterol (LDL-C) the serum cholesterol carried on low-density lipoproteins, approximately 60 to 70 per cent of the total.

cholesterol

(kə-lĕs′tə-rôl′, -rōl′)
n.
A white crystalline substance, C27H45OH, that is found in animal tissues and various foods and is important as a constituent of cell membranes and a precursor to steroid hormones. Cholesterol is normally synthesized by the liver and is transported through the bloodstream by different types of lipoproteins, two of which (HDL and LDL) are routinely measured in blood tests.

cholesterol

[kəles′tərôl]
Etymology: Gk, chole + steros, solid
a waxy lipid soluble compound found only in animal tissues. A member of a group of compounds called sterols, it is an integral component of every cell in the body. It facilitates the absorption and transport of fatty acids. Cholesterol acts as the precursor for the synthesis of various steroid hormones, including cortisol, cortisone, and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone. It sometimes precipitates along with other compounds in the gallbladder to form gallstones. Cholesterol is found in foods of animal origin and is continuously synthesized in the body, primarily in the liver. Increased levels of low-density lipoprotein cholesterol may be associated with the pathogenesis of atherosclerosis, whereas higher levels of high-density lipoprotein cholesterol appear to lower the person's risk for heart disease. Normal adult levels of blood cholesterol are 150 to 200 mg/dL or 3.9 to 5.2 mmol/L (SI units). Also called cholesterin. See also high-density lipoprotein, low-density lipoprotein, sterol.
enlarge picture
Chemical structure of cholesterol

cholesterol

A 27-carbon precursor of steroid hormones and bile acids which is an integral component of cell membranes and plasma lipoproteins; it is a precursor of bile acids and important in the synthesis of steroid hormones. It is the main component of the most common type of gallstones and is a major constituent of arterial atheromas; increased cholesterol is associated with ASHD, CAD, increased risk of death due to acute MIs and strokes.
 
Sources
Animal fat, bile, blood, brain, milk, egg yolk, myelin sheaths, liver, kidneys, adrenal gland.

Metabolism
Cholesterol is absorbed from ingested foods—diets high in saturated (animal) fats increase cholesterol levels—and synthesised in the liver. HDL-C is metabolised efficiently, and thus is “good” cholesterol; “bad cholesterol”, LDL-C, is inefficently metabolised; when the total cholesterol (TC) is increased (usually = 200 mg/dL), it is common practice to measure the levels of HDL-cholesterol and LDL-cholesterol.
 
Lab
TC is measured in routine chemistry panels; cholesterol is transported in the circulation by carrier proteins, which are classified according to their density (HDL, LDL, VLDL) based on density-gradient ultracentrifugation.
 
High risk for ASHD
• TC > 6.21 mmol/L—US: > 240 mg/dL;
• LDL-C > 160 mg/dl;
• HDL-C < 35 mg/dl.
Borderline risk
• TC = 5.17–6.18 mmol/L—US: 200–239 mg/dL;
Low risk
• TC < 5.17 mmol/L—US: 200 mg/dL;
• LDL-Cl < 130 mg/dL;
• HDL-C > 55 mg/dL.
 
Increased in
Hypercholesterolemia, nephrotic syndrome, hypothyroidism, biliary cirrhosis, high saturated fats in diet.
 
Decreased in
Malnutrition, hyperthyroidism, colorectal CA.
 
Management, hypercholesterolemia
Diet (decreased saturated fats), weight loss, regular exercise, medications.

cholesterol

Biochemistry A precursor of steroid hormones and bile acids; it is an integral component of cell membranes and plasma lipoproteins, and found in animal fats, bile, blood, brain, milk, egg yolk, myelin sheaths, liver, kidneys, and adrenal glands; it is absorbed from the diet and synthesized in the liver; diets high in saturated–animal fats ↑ cholesterol levels; it is the main component of the most common type of gallstones, and integral to arterial atheromas, in cysts and in malignancy; it is a precursor of bile acids and important in the synthesis of steroid hormones; diets low in saturated fats ↓ cholesterol levels, as does exercise; ↑ cholesterol is associated with ASHD, CAD, ↑ risk of death due to acute MIs and strokes; total cholesterol–TC is measured in routine chemistry panels; cholesterol is transported in the circulation by carrier proteins, which are classified according to their density–high-density lipoprotein—HDL, LDL, VLDL, based on density gradient ultracentrifugation; HDL-C is metabolized efficiently, and thus is 'good' cholesterol; 'bad cholesterol,' LDL-C, is inefficently metabolized High risk for ASHD TC > 6.21 mmol/L–US > 240 mg/dL; LDL-C > 160 mg/dl, HDL-C
< 35 mg/dl Borderline risk 5.17-6.18 mmol/L–US: 200-239 mg/dL Low risk < 5.17 mmol/L–US 200 mg/dL, LDL-Cl < 130 mg/dL, HDL-C > 55 mg/dL ↑ in Hypercholesterolemia, nephrotic syndrome, hypothyroidism, biliary cirrhosis ↓ in Malnutrition, hyperthyroidism, colorectal CA Management, ↑ cholesterol Diet–↓ saturated fats, weight loss, regular exercise, medications. See Bad cholesterol, Fish, Good cholesterol, HDL, Hypercholesterolemia, LDL, RLP, VLDL.

cho·les·ter·ol

(kŏ-les'tĕr-ol)
The most abundant steroid in animal tissues; circulates in the plasma complexed to proteins of various densities; plays an important role in the pathogenesis of atheroma formation in arteries.

cholesterol

An essential body ingredient found in all human cells, mainly as part of the structure of the cell membranes. It is needed to form the essential steroid hormones, CORTISOL, corticosterone and ALDOSTERONE, the male and female sex hormones and the bile acids. It is synthesized in the liver and a large quantity of cholesterol passes down the bile duct into the intestine every day. Most of it is reabsorbed. A diet high in saturated fats encourages high blood cholesterol levels. Soluble dietary fibre and various drugs can bind intestinal cholesterol and prevent its reabsorption. Cholesterol is carried to the tissues in tiny cholesterol carriers called low density lipoproteins (LDLs). Oxidation of these allows cholesterol to be deposited in the walls of arteries causing dangerous narrowing (ATHEROSCLEROSIS).

cholesterol

a steroid that occurs in the cell membranes of animal cells, but not in plants. Cholesterol is produced in the liver and when in excess is excreted in the bile but is partly reabsorbed by the ileum. It may precipitate gallstones in the gallbladder or bile duct. Alternatively, if there is excess cholesterol in the blood, it may be deposited on the walls of the blood vessels, obstructing them and often leading to an intravascular clot which if it occurs in the region of the heart gives rise to a ‘heart attack’ or coronary thrombosis. Cholesterol is the precursor of animal steroid hormones and bile acids.

Cholesterol

A fat-like substance that is made by the human body and eaten in animal products. Cholesterol is used to form cell membranes and process hormones and vitamin D. High cholesterol levels contribute to the development of atherosclerosis.

cholesterol

a sterol which is essential for the formation of cell membranes and for the synthesis of steroid hormones and bile acids. Some is ingested in foods such as egg yolk, but most is made in the liver. Circulates in the blood combined with high-density and low-density lipoproteins (HDL and LDL). HDL-cholesterol removes excess cholesterol from cells and transports it to the liver for excretion; LDL-cholesterol delivers cholesterol to cells of all organs and tissues. An abnormally high concentration of total and particularly LDL-cholesterol increases uptake of cholesterol by the cells of arterial walls, promoting atherosclerosis.

cholesterol

most abundant naturally occurring steroid; raised blood cholesterol levels link strongly to atheroma formation and vascular disease (normal values = 3.5-6.5 mmol/L; ideally < 5.2 mmol/L)

cholesterol (k·lesˑ·ter·l),

n organic compound produced in the liver and absorbed from food that is essential to the production of metabolic products and hormones.
Enlarge picture
Cholesterol.

cho·les·ter·ol

(kŏ-les'tĕr-ol)
The most abundant steroid in animal tissues; circulates in the plasma complexed to proteins of various densities; plays an important role in the pathogenesis of atheroma formation in arteries.

cholesterol (kəles´tərôl),

n a lipid common to all animal, but not plant, cells. As a sterol, it contains the cyclopentanophenanthrene nucleus. High levels are found in nerve tissue, atheromas, gallstones, and cysts. Normally 140 to 220 mg are present in 100 ml of blood.

cholesterol

a steroid alcohol found in animal fats and oils, bile, blood, brain tissue, milk, egg yolk, myelin sheaths of nerve fibers, liver, kidneys and adrenal glands. It is a necessary component of all cell surface and intracellular membranes and a constituent of myelin in nervous tissue; it is a precursor of bile acids and steroid hormones, and it occurs in the most common type of gallstone, in atheroma of the arteries, in various cysts, and in carcinomatous tissue. Most of the body's cholesterol is synthesized, but some is obtained in the diet.
The preoccupation in human medicine with the relationship between cholesterol and the development of atheromatous plaques in the coronary arteries is not reflected in veterinary medicine. The importance of cholesterol to the veterinarian is limited to the measurement of blood cholesterol levels as an indicator of liver disease or thyroid activity.

cholesterol pneumonia
see endogenous-lipid pneumonia.

Patient discussion about cholesterol

Q. How to lower high cholesterol? The Doctor told my husband that his cholesterol levels are very high and that he has to lower them immediately. What foods are low in cholesterol and what foods should I be cooking for him to eat?

A. Any treatment of high cholesterol first begins with some lifestyle changes. This involves three simple, yet often difficult to execute, steps: improved diet, increased physical activity, and weight management.
Make sure your Husband is eating unsaturated fats instead of saturated and trans fats, avoiding cholesterol, increasing dietary fiber, and consuming more plant sterols/stanols. Increase his vegetables and whole grains intake, but decrease the fat, salt and sugar intakes.
Also, it will be easier for him to stick to his diet if the whole family changes their eating habits and eats healthier too. Start cooking healthy meals for the whole family and not just for him.

Q. I have high cholesterol. What I need to do in order to reduce him?

A. How to Eat to Lower Your Cholesterol
Things You’ll Need:
Flaxseed
Fruits
Garlic
Kidney Beans
Oatmeal
Soy Foods Like Tofu
Vegetables
White Beans
Step1Eat more garlic. Add it to pasta, soups and vegetables.
Step2Increase your intake of soy foods. Enjoy more tofu, green soybeans (edamame), tempeh and TVP (texturized vegetable protein).
3Add beans to your diet three to five times a week. Try lentil soup, black beans and rice, and hummus, and toss kidney beans into green salads.
Step4Include a serving of fiber-rich fruit or vegetables at every meal and snack.
For full article: http://www.ehow.com/how_12776_eat-lower-cholesterol.html?ref=fuel&utm_source=yahoo&utm_medium=ssp&utm_campaign=yssp_art Hope this helps.

Q. Which cholesterol is the bad cholesterol and what level is considered high cholesterol? I keep on hearing about cholesterol and how it is bad for you though I understand that there are two kinds of cholesterol and that only one of them is bad, which is it? Also, what level is considered high cholesterol?

A. Cholesterol can’t dissolve in the blood. It has to be transported to and from the cells by carriers called lipoproteins. Low-density lipoprotein, or LDL, is known as “bad” cholesterol. High-density lipoprotein, or HDL, is known as “good” cholesterol. These two types of lipids, along with triglycerides and Lp(a) cholesterol, make up your total cholesterol count, which can be determined through a blood test. If your total cholesterol is 200 mg/dL or greater, or if your HDL is less than 40 mg/dL, then you will probably need treatment.

More discussions about cholesterol