Cholesterol and Low Cholesterol Diets
Benefits of Eating a Low Cholesterol Diet
The liver makes most of the cholesterol in the body, but dietary cholesterol plays an important role in controlling all the cholesterol levels in the body. The levels include the total cholesterol and the good and bad cholesterol. Good cholesterol, the HDL (high-density lipoproteins), protects the heart by helping to transport excess cholesterol from the arteries back to the liver for breakdown and disposal. On the other hand, the bad LDL (low-density lipoproteins) cholesterol builds up plaque that clogs the arteries and hinders normal blood flow. A low cholesterol diet should not only reduce the total cholesterol and LDL levels, it must also increase the HDL level at the same time.
The main sources of dietary cholesterol are animal-derived foods rich in cholesterol and saturated fats, such as organ meats, egg yolk, butter and other full-cream dairy products. Trans fats (as those in deep-fried foods) and hydrogenated fats (as those in bakery items) are the other culprits. In a low cholesterol diet, you would replace saturated fats with polyunsaturated and monounsaturated fats such as oils of olive, canola, peanut, flaxseed, sunflower, and so on.
Fats to Avoid
As far as trans fats and hydrogenated fats are concerned, it is advisable to avoid them as far as possible, which means taking away French fries, crispies, cakes, cookies, pastries, and ice-creams from the low cholesterol diet menu.
Recommended Low Cholesterol Diet
Foods that should make an essential part of a low cholesterol diet must come from the following food groups:
Cereals and grains: Whole-wheat bread, unpolished rice, and oats-based cereals are foods that are rich in fiber, which helps sweep away the bad LDL cholesterol from the blood. In a low cholesterol diet it is essential to replace white bread and other refined, polished grains with whole-grain varieties.
Nuts and seeds: Nuts like almonds, peanuts, walnuts and seeds like flaxseeds are rich in antioxidants (such as vitamin E and selenium) and in good fats, called omega-3 fatty acids, which protect the heart by increasing the HDL level. Nuts and seeds are also a rich source of fiber. The best way to include flaxseeds in a low cholesterol diet is by grinding them and sprinkling over cereals and salads.
Fish: Non vegetarians can choose to have a fatty cold-water fish such as salmon or tuna twice a week to get a rich supply of omega-3 fatty acids.
Beans and legumes: Beans, legumes and lentils are rich sources of protein and fiber and are low in fat content. They make an ideal substitute for meats. Soy cheese (tofu) is another good meat substitute in a low cholesterol diet.
Fiber-rich foods: Foods like oats, barley, psyllium, apples, pears, prunes, kidney beans and Brussels sprouts are rich in soluble fiber, which acts like a broom to sweep out the cholesterol from the arteries.
Fruits and vegetables: Fresh fruits and vegetables are loaded with fiber, antioxidants, flavanoids and plant sterols, all of which help lower cholesterol and raise HDL level. Some 8–10 servings of fruits and vegetables should be included in the daily low cholesterol diet.
Garlic, onion: Some people believe garlic regulates liver functioning and dissolve the cholesterol deposits in the arteries. Others swear that including just half a raw onion in the daily low cholesterol diet can lower LDL level and increase HDL level.
Following a low cholesterol diet, with regular exercise, and cutting out on meats, full-cream dairy products, deep-fried foods and bakery items, can go a long way in lowering total cholesterol. Similarly, it lowers LDL cholesterol levels while raising the HDL level.
Help Lower Your Cholesterol - Read Food Labels
Very often shoppers don't pay enough attention to food labels while grocery shopping. People shop when they are in a rush and just can't be bothered to examine each and every item. If you suffer from high cholesterol and are attempting to stick to a "cholesterol diet" in order to lower your cholesterol it's an extremely good idea to read those food labels and find out what is actually going to be going into your mouth! It is also mandatory for food manufacturers to list pertinent and correct information about what each food is comprised of.
Here are the essential things to look for on food labels when you want to lower your cholesterol and gain or maintain good health.
The exception for having food labels is fresh produce and bulk foods. It is understood that these foods are healthy and don’t have any fat or high percentage of cholesterol.
Some eating establishments have realized the importance of food value information. They have implemented their own lists for the health-conscious patrons. Many of these restaurants have also started offering healthy meals containing minimal amounts of fat.
In summary, if you are on a cholesterol diet, increased knowledge and understanding about the different foods which raise and lower cholesterol means increased ability to make smarter and more educated choices about your health. So, read up on which foods to be careful about and make sure you read those food labels carefully!
Lynn Ruder is a mother and an active health researcher with a lot of knowledge about health related subjects. To learn more about ways to lower cholesterol visit her site http://www.lowercholesterol.blogspot.com
Cholesterol is a steroid, a lipid, and an alcohol, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. Most cholesterol is not dietary in origin, it is synthesized internally. It is present in higher concentrations in tissues which either produce more or have more densely packed membranes; for example the liver, spinal cord, brain and atheroma. Cholesterol plays a central role in many biochemical processes, but is best known for the association of cardiovascular disease with various lipoprotein cholesterol transport patterns in the blood.
History of the name
The name originates from the Greek chole- (bile) and stereos (solid), as researchers first identified cholesterol in solid form in gallstones.
Physiology of cholesterol
Synthesis and intake
Cholesterol is primarily synthesized from acetyl CoA through the HMG-CoA reductase pathway in many cells/tissues. About 20–25% of total daily production (~1 g/day) occurs in the liver, other sites of higher synthesis rates include the intestines, adrenal glands and reproductive organs. For a person of about 150 pounds (68 kg), typical total body content is about 35 g, typical daily internal production is about 1 g and typical daily dietary intake is 200 to 300 mg. Of the 1,200 to 1,300 mg input to the intestines (via bile production and food intake), about 50% is typically reabsorbed into the bloodstream.
Cholesterol is minimally soluble in water; it cannot dissolve and travel in the water-based bloodstream. Instead, it is transported in the bloodstream by lipoproteins; protein "molecular-suitcases" which are water soluble and carry cholesterol and fats internally. The proteins forming the surface of the given lipoprotein particle determine from what cells cholesterol will be removed and to where it will be supplied.
The largest lipoproteins, which primarily transport fats from the intestinal mucosa to the liver are called chylomicrons. They carry mostly triglyceride fats and cholesterol (both from food and especially internal cholesterol secreted by the liver into the bile). In the liver, chylomicron particles give up triglycerides and some cholesterol and are converted into low-density lipoprotein (LDL) particles which carry triglycerides and cholesterol on to other body cells. In healthy individuals the LDL particles are large and relatively few in number. Conversely, large numbers of small LDL particles are strongly associated with promoting atheromatous disease within the arteries. (Lack of information on LDL particle number and size is one of the major problems of conventional lipid tests.)
High density lipoprotein (HDL) particles transport cholesterol back to the liver for excretion, but vary considerably in their effectiveness for doing this. Having large numbers of large HDL particles correlates with better health outcomes. Conversely, having small amounts of large HDL particles is strongly associated with atheromatous disease progression within the arteries. (Note that the concentration of total HDL does not indicate the actual number of functional large HDL particles, another of the major problems of conventional lipid tests.)
The cholesterol molecules present in LDL cholesterol and HDL cholesterol are identical. The difference between the two cholesterol derives from the carrier protein molecules; the lipoprotein component.
Biosynthesis of cholesterol is directly regulated by the cholesterol levels present, though the homeostatic mechanisms involved are only partly understood. A higher intake in food leads to a net decrease in endogenous production and vice versa. The main regulatory mechanism is the sensing of intracellular cholesterol in the endoplasmic reticulum by the protein SREBP (Sterol Regulatory Element Binding Protein 1 and 2). In the presence of cholesterol, SREBP is bound to two other proteins: SCAP (SREBP-cleavage activating protein) and Insig-1. When cholesterol levels fall, Insig-1 dissociates from the SREBP-SCAP complex, allowing the complex to migrate to the Golgi apparatus, where SREBP is cleaved by S1P and S2P (site 1/2 protease), two enzymes that are activated by SCAP when cholesterol levels are low. The cleaved SREBP then migrates to the nucleus and acts as a transcription factor to bind to the "Sterol Regulatory Element" of a number of genes to stimulate their transcription. Amongst the genes transcribed are the LDL receptor and HMG-CoA reductase. The former scavenges circulating LDL from the bloodstream, while HMG-CoA reductase leads to an increase of endogenous production of cholesterol.
A large part of this mechanism was clarified by Dr Michael S. Brown and Dr Joseph L. Goldstein in the 1970s. They received the Nobel Prize in Physiology or Medicine for their work in 1985.
The average amount of blood cholesterol varies with age, typically rising gradually until one is about 60 years old. A study by Ockene et al. showed that there are seasonal variations in cholesterol levels in humans, more on average in winter.
Cholesterol is an important component of the membranes of cells, providing stability; it makes the membrane's fluidity stable over a bigger temperature interval. The hydroxyl group on cholesterol interacts with the phosphate head of the membrane and the bulky steroid and the hydrocarbon chain is embedded in the membrane. It is the major precursor for the synthesis of vitamin D, of the various steroid hormones, including cortisol, cortisone, and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone. The presence of cholesterol has a direct effect on the fluidity of the membrane. Further recent research shows that cholesterol has an important role for the brain synapses as well as in the immune system, including protecting against cancer.
Cholesterol is excreted from the liver in bile and reabsorbed from the intestines. Under certain circumstances, when more concentrated, as in the gallbladder, it crystallises and is the major constituent of most gallstones, although lecitin and bilirubin gallstones also occur less frequently.
Role in atheromatous disease
In conditions with elevated concentrations of LDL particles, especially small LDL particles, cholesterol promotes atheroma plaque deposits in the walls of arteries, a condition known as atherosclerosis, which is a major contributor to coronary heart disease and other forms of cardiovascular disease. (Conversely, HDL particles have been the only identified mechanism by which cholesterol can be removed from atheroma. Increased concentrations of large HDL particles, not total HDL particles, correlate with lower rates of atheroma progressions, even regression.)
There is a world-wide trend that lower total cholesterol levels tend to correlate with lower atherosclerosis event rates. However, the primary association of atherosclerosis with cholesterol has always been specifically with cholesterol transport patterns, not total cholesterol per se. For example, total cholesterol can be low, yet made up primarily of small LDL and small HDL particles and atheroma growth rates are high. Conversely, if LDL particle number is low (mostly large particles) and a large percentage of the HDL particles are large (HDL is actively reverse transporting cholesterol), then atheroma growth rates are usually low, even negative, for any given total cholesterol concentration.
Multiple human trials utilizing HMG-CoA reductase inhibitors or "statins", have repeatedly confirmed that changing lipoprotein transport patterns from unhealthy to healthier patterns significantly lower cardiovascular disease event rates, even for people with cholesterol values currently considered low for adults; however, no statistically significant mortality benefit has been derived to date by lowering cholesterol using medications in asymptomatic people, i.e. no heart disease, no history of heart attack, etc. In fact many cholesterol trials show a trend towards higher cancer mortility in the older popultations. The statins produce a mortality benefit in many populations independently of their cholesterol lowering capability. [This data is somewhat controversial and incideary, though, you have to read the statistics/materials methods to convince yourself. Be wise, always discern if the author(s) have a conflict of interest in the results of their trials.]
Some of the better recent randomized human outcome trials studying patients with coronary artery disease or its risk equivalents include the Heart Protection Study (HPS), the PROVE IT trial, and the TNT trial. In addition, there are trials that have looked at the effect of lowering LDL as well as raising HDL and atheroma burden using intravascular ultrasound. Small trials have shown prevention of progression of coronary artery disease and possibly a slight reduction in atheroma burden with successful treatment of an abnormal lipid profile.
The American Heart Association provides a set of guidelines for total
(fasting) blood cholesterol levels and risk for heart disease:
However, as today's testing methods determine LDL ("bad") and HDL ("good") cholesterol separately, this simplistic view has become somewhat outdated. The desirable LDL level is considered to be less than 100 mg/dl (2.6 mmol/L),although a newer target of <70 mg/dl can be considered in higher risk individuals based on some of the above mentioned trials. A ratio of total cholesterol to HDL —another useful measure— of far less than 5:1 is thought to be healthier. Of note, typical LDL values for children before fatty streaks begin to develop is 35 mg/dl.
Patients should be aware that most testing methods for LDL do not actually measure LDL in their blood, much less particle size. For cost reasons, LDL values have long been estimated using the formula: Total-cholesterol - total-HDL - 20% of the triglyceride value = estimated LDL.
Increasing clinical evidence has strongly supported the greater predictive value of more sophisticated testing which directly measures both LDL and HDL particle concentrations and size as opposed to the more usual estimates/measures of the total cholesterol carried within LDL particles or the total HDL concentration. There are three commercial labs in the United States which offer more sophisticated analysis using different methodologies. As outlined above, the real key is cholesterol transport which is determined by both the proteins which form the lipoprotein particles and the proteins on cell surfaces with which they interact.
Cholesteric liquid crystals
Some cholesterol derivatives, (among others simple cholesteric lipids) are known to generate liquid crystalline phase called "cholesteric". The cholesteric phase is in fact a chiral nematic phase and changes colour when its temperature changes. Therefore cholesterol derivatives are commonly used as temperature sensitive dyes, in liquid crystal thermometers, and in temperature sensitive paints.
Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults US National Institutes of Health Adult Treatment Panel III
The Weston A. Price Foundation is a group that questions the connection between cholesterol and atheroma.
Cholesterol and Health (alternative views on cholesterol's relationship to disease)
The Cholesterol Myths Uffe Ravnskov, M.D., Ph.D.