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Cholesterol Lowering Of Phytosterol

Cholesterol lowering

The ability of phytosterols to reduce cholesterol levels was first demonstrated in humans in 1953. They were subsequently marketed as a pharmaceutical under the name Cytellin as a treatment for elevated cholesterol from 1954-1982.

Unlike the statins, where cholesterol lowering has been proven to reduce CVD risk and overall mortality under well-defined circumstances, no such effect has ever been documented with phytosterol-enriched foods or phytosterol OTC medications. While cholesterol lowering was frequently used as a surrogate endpoint for beneficial effects on CVD, counter-examples exist where specific medications for cholesterol lowering were found to have unfavorable effect on clinical endpoints, such as with ezetimibe.

Coadministration of statins with phytosterol-enriched foods increases the cholesterol-lowering effect of phytosterols, again without any proof of clinical benefit and with anecdotal evidence of dangerous adverse effects.

Statins work by reducing cholesterol synthesis by inhibiting the rate-limiting HMG-CoA reductase enzyme. Phytosterols reduce cholesterol levels by competing with cholesterol absorption in the gut, a mechanism which complements statins. Phytosterols further reduce cholesterol levels by about 9% to 17% in statin users. The type or dose of statin does not appear to affect phytosterols’ cholesterol-lowering efficacy.

Because of their cholesterol reducing properties, some manufacturers are using sterols or stanols as a food additive.

 

Triglycerides

Elevated triglyceride levels are a risk factor for CVD. Triglycerides were found to be reduced by 14% in individual supplementing 1.6 g/day of plant sterols in a fermented milk beverage for six weeks. The proposed mechanism behind the triglyceride-lowering effect of phytosterols is a reduction in triglyceride-rich VLDL particles produced by the liver. These effects of phytosterols may be more pronounced in people with elevated triglycerides

 

Cancer risk

Phytosterols may inhibit lung, stomach, ovarian and breast cancers. 24-Epibrassinolide, a brassinosteroid, modulates superoxide dismutase, catalase, and glutathione peroxidase activity.

 

Safety

Phytosterols have a long history of safe use dating back to Cytellin, the pharmaceutical preparation of phytosterols marketed in the US from 1954 to 1982. Phytosterol esters have generally recognized as safe(GRAS) status in the US. Phytosterol-containing functional foods were subject to postlaunch monitoring after being introduced to the EU market in 2000, and no unpredicted side effects were reported. 

A potential safety concern regarding phytosterol consumption is in patients with phytosterolaemia, a rare genetic disorder which results in a 50- to 100-fold increase in blood plant sterol levels and is associated with rapid development of coronary atherosclerosis. Phytosterolaemia has been linked to mutations in the ABCG5/G8 proteins which pump plant sterols out of enterocytes and hepatocytes into the lumen and bile ducts, respectively. Plant sterol levels in the blood have been shown to be positively, negatively or not associated with CVD risk, depending on the study population investigated. 

The link between plant sterols and CVD or CHD risk is complicated because phytosterol levels reflect cholesterol absorption. (See Phytosterols as a marker for cholesterol absorption).

 

Sterol vs stanol

The equivalent ability and safety of plant sterols and plant stanols to lower cholesterol continues to be a hotly debated topic. Plant sterols and stanols, when compared head to head in clinical trials, have been shown to equally reduce cholesterol levels. A meta-analysis of 14 randomized, controlled trials comparing plant sterols to plant stanols directly at doses of 0.6 to 2.5 g/day showed no difference between the two forms on total cholesterol, LDL cholesterol, HDL cholesterol, or triglyceride levels. Trials looking at high doses (> 4 g/day) of plant sterols or stanols are very limited, and none have yet to be completed comparing the same high dose of plant sterol to plant stanol.

The debate regarding sterol vs. stanol safety is centered on their differing intestinal absorption and resulting plasma concentrations. Due to the extremely elevated levels of phytosterols seen in the rare genetic disorder phytosterolemia (sitosterolemia), which is associated with rapidly progressing CVD, it was hypothesized that plant sterols themselves may be atherogenic. suggested elevated plant sterol levels may be related to increased CVD risk because campesterol and total plant sterols correlated positively with cholesterol. Several other studies have suggested elevated plant sterol levels may be a risk factor for CVD. In these studies, though, the plant sterol levels were not as high as those seen in phytosterolemia. In phytosterolemia, the rapid development of CVD is most likely due to the improper handling of cholesterol, which is elevated and accounts for the vast majority of sterols in phytosterolemics. Because plant sterol levels actually reflect cholesterol absorption, some have concluded elevated cholesterol absorption, not plant sterols are atherogenic or otherwise associated with CVD risk.

 

 

Sources of Phytosterols

Overview

Phytosterols are compounds naturally found in plants that reduce the amount of cholesterol your body absorbs, according to Oregon State University’s Linus Pauling Institute. This can reduce blood cholesterol levels, which can help lower the risk of heart disease. Traditional diets, before the advent of processed foods, provided as much as 1000 milligrams of physterols per day. Today, someone eating a typical Western diet consumes less than half that amount. All plant foods provide some phytosterols.

Oils

Plant oils are the most highly concentrated source of phytosterols but they should be unrefined in order to preserve these heart-healthy compounds, according to the Linus Pauling Institute. A tbsp. of sesame oil provides 118 milligrams of phytosterols while the same amount of corn oil provides 102 milligrams. Other good choices include canola and olive oils. A 2002 study in the "American Journal of Clinical Nutrition" found that when phytosterols were removed from commercial corn oil, cholesterol absorption increased 38 percent. The study also found that the phytosterol content of refined oils varies greatly depending on how the product is refined.

Nuts and Seeds

Nuts and seeds are also an excellent source of phystosterols, according to the Linus Pauling Institute. Snack on pistachios and sunflower seeds, as they contain the highest amount of phytosterols among common snack foods, according to a study published in the "American Journal of Agricultural and Food Chemistry" in 2005. The researchers in the study looked at 27 different varieties of nuts and seeds. Sesame seeds and wheat germ actually provided higher concentrations of phytosterols but the researchers felt that most people don’t eat those foods in amounts large enough to make a real difference. A ½ cup of wheat germ provides 197 milligrams of phytosterols. Other good choices include peanuts, almonds and macademia nuts.

Fortified Foods

Phytosterols have been added to a number of foods in recent years and have been shown in clinical trials to help lower cholesterol, according to the Linus Pauling Institute. A tbsp. of phytosterol-enriched margarine can contain 850 to 1650 mg of phytosterols, depending on the brand. Other phytosterol-fortified foods include mayonnaise, yogurt, milk, cheese, chocolate, orange juice, vegetable oils, salad dressings, soymilk and snack bars. Read the nutrition label to find out whether and how many phytosterols a particular product contains.

Other Sources

Some grains contain significant quantities of phytosterols, according to the Linus Pauling Institute. A ½ cup of wheat bran contains 58 mg while two slices of rye bread provide 33 mg. Brussels sprouts are also high in phytosterols, providing 34 mg in a ½ cup serving. Supplements are also available in the form of beta-sitosterol pills or a soft chew. These supplements should be taken with meals that contain fat in order to reduce absorption of cholesterol, according to the Linus Pauling Institute.

 

Another Version:

Natural Sources of Plant Sterols

Naturally occurring chemicals in plants, known as phyto-chemicals, include sterols, stanols and flavanoids. Harvard Health Publications reports that eating about two grams of sterols daily can lower LDL cholesterol by about 10 percent. You can purchase many foods, such as margarine and orange juice, that are fortified with plant sterols and you can also eat plants or oil derived from plants that contain sterols.

Corn Oil

Corn oil, used for frying, cooking, in salad dressings and spreads, contains approximately 968 mg of sterols per 100 grams of oil. Like soybean oil, the chief sterol in corn oil is betasitosterol.

Soybean Oil

Oil from soybeans contains approximately 161 mg. of sterols per 100 grams of oil, according to analysis by the United States Department of Agriculture. Soybean oil is an ingredient in some salad dressings, mayonnaise and butter substitute spreads. The primary sterol in soybean oil is betasiytosterol, according to Syed Mubbasher Sabir, Imran Hyat, et al. from the Department of Biochemistry at the University College of Agriculture in Rawalakot, Pakistan, who have studied the role of plant sterols in lowering cholesterol.

Mustard

In analysis published in the "Pakistan Journal of Nutrition," in 2003, mustard oil, derived from mustard plants, contained the highest concentration of plant sterols of the species tested, 6400 mgs. of sterols per 100 grams of mustard oil. Eating mustard greens is another way to consume sterols, though in a less concentrated form than you'd get from plant oils. Mustard and other members of the cabbage or brassica family, such as kale, brocolli and cabbage contain brassicasterol.

Tree Nuts

Nuts also contain plant sterols. USDA analysis determined that pecans contain 108 mg. of sterols per 100 grams of nuts, while almond contain 143 mg. and cashews 158 mg. Nuts also contain monosaturated fats and fiber, which can also be helpful in lowering cholesterol.

Beans and Peanuts

Beans and peanuts are another good source of sterols in your diet. The USDA determines peanuts contain 220 mg. of sterols per 100 grams of nuts, while kidney beans and garbanzo beans contain 127 mg. and 35 mg. respectively.

 

 

 

Benefits of Phytosterols

Overview

Phytosterols are compounds found in plants that resemble cholesterol. The National Institutes of Health report that there are over 200 different phytosterols, and the highest concentrations of phytosterols are found naturally in vegetable oils, beans and nuts. Their benefits are so recognized that foods are being fortified with phytosterols. At the supermarket, you may see orange juice or margarine advertising phytosterol contents. After reviewing the health benefits, you may want to add phytosterol-rich foods to your diet.

 

Cholesterol-Lowering Benefits

The most well-known, and scientifically proven, benefit of phytosterols is their ability to help lower cholesterol. A phytosterol is a plant compound that is similar to cholesterol. A study in the 2002 issue of "Annual Review of Nutrition" explains that phytosterols actually compete for absorption with cholesterol in the digestive tract. While they prevent the absorption of regular dietary cholesterol, they themselves are not easily absorbed, which leads to a total lower cholesterol level. The cholesterol-lowering benefit does not end with a good number on your blood work report. Having lower cholesterol leads to other benefits, such as a reduced risk for heart disease, stroke and heart attacks.

 

Cancer Protection Benefits

Phytosterols have also been found to help protect against the development of cancer. The July 2009 issue of the" European Journal of Clinical Nutrition" offers encouraging news in the fight against cancer. Researchers at the University of Manitoba in Canada report that there is evidence that phytosterols help prevent ovarian, breast, stomach and lung cancer. Phytosterols do this by preventing the production of cancer cells, stopping the growth and spread of cells that are already in existence and actually encouraging the death of cancer cells. Their high anti-oxidant levels are believed to be one way phytosterols help fight cancer. An anti-oxidant is a compound that fights free radical damage, which is negative effects on the body produced by cells that are unhealthy.

 

Skin Protection Benefits

A lesser known benefit of phytosterols involves skin care. One of the contributing factors in the aging of the skin is the breakdown and loss of collagen -- the main component in connective skin tissue -- and sun exposure is a major contributor to the problem. As the body ages, it is not able to produce collagen as it once did. The German medical journal "Der Hautarzt" reports a study in which various topical preparations were tested on skin for 10 days. The topical treatment that showed anti-aging benefits to the skin was the one that contained phytosterols and other natural fats. It is reported that phytosterols not only stopped the slow-down of collagen production that can be caused by the sun, it actually encouraged new collagen production.

 

Heart Protective Benefits

Several studies indicate that plant sterols lower LDL cholesterol and total serum cholesterol by inhibiting the intestinal absorption of dietary and liver-synthesized cholesterol. Because beta-sitosterol is very similar in structure to cholesterol, it displaces cholesterol in micelles in the small intestines. Micelles are tiny complexes of emulsified fat that arises during digestion. Each micelle carries dozens of bile acids and fatty acids.Only 50 percent of dietary cholesterol is assimilated. Unabsorbed cholesterol is returned to the liver or ferried out with bile acids for excretion. In normal healthy persons, less than five percent of plant sterols is assimilated, and less than 0.5 percent plant stanols are absorbed.


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