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| Heart Disease |
Excess cholesterol in the blood collects on the walls of certain blood vessels, decreasing their ability to provide proper blood flow to the tissues fed by these blood vessels. For example, a heart attack occurs when the heart receives insufficient blood flow. High levels of cholesterol also increase the risk of high blood pressure, stroke, and circulation problems.
Cholesterol can be affected by consuming foods high in fat, but the body also synthesizes cholesterol. Some people that adhere to a low fat diet still have high cholesterol levels because their body synthesizes an excess amount. There are several forms in which cholesterol is present in the body, LDL (the harmful form) and HDL (the helpful form). Depending on the relative levels of these forms, along with the concentration of triglycerides (another type of body fat), certain drugs are more effective then others in correcting the abnormalities. For example, a person with elevated LDL levels and normal triglycerides may be treated with different medications than someone with only elevated triglycerides.
As with all medications, cholesterol lowering drugs have a risk of side effects, so it is important for a physician to routinely monitor people receiving these drugs. Sometimes a combination of drugs is used. In addition to cholesterol, it is important for women to have their HDL and triglyceride levels monitored because these appear to be stronger risk factors for heart disease in women than men.
This rise in the incidence of CHD at the time when estrogen levels decline has led to the common use of hormone replacement therapy (HRT) at menopause and thereafter. Estrogen has been shown to lower cholesterol levels, one of the risk factors for CHD. The use of estrogen alone can increase a womans risk for endometrial cancer, however the risk is almost eliminated when estrogen is taken in combination with progestins, compounds similar to the hormone progesterone. Women who have had hysterectomies can take estrogen alone.
In postmenopausal women without a history of heart disease, HRT appears to offer a protective effect for the heart, but in the presence of established heart disease, it doesn’t appear to prevent heart attacks. Aggressive treatment of elevated cholesterol levels with drugs other than or in addition to HRT or other substances with estrogenic activity is currently recommended.
Findings from trials currently under way will be useful for providing conclusions about the long-term use of HRT in the prevention of CHD. Currently, the use of HRT for the treatment of menopausal symptoms is often indicated. The decision to use HRT for the prevention of heart disease should be made on an individual basis, taking into account the history of the individual or their predisposition for experiencing a side effect from the therapy.
Other compounds with estrogenic activity may be used in postmenopausal women to help prevent elevations in cholesterol levels, however their effects are weak in comparison to cholesterol lowering drugs such as the statins. The selective estrogen receptor modulators (SERMs) act like estrogen in bone and cardiovascular tissue and block estrogenic effects in the breast. They do not appear to increase the risk of breast cancer that is associated with some of the traditional HRTs. SERMs decrease LDL and cholesterol levels, but the overall effectiveness in protecting the heart have not been established. Like traditional HRT, these drugs can increase the risk of blood clots.
Phytoestrogens
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| Women, Heart Disease, and High Cholesterol |
Statins
The statins are a class of drugs frequently used to reduce cholesterol. Some examples of statins are Lipitor®, Mevacor® and Baycol®. They are the most potent cholesterol reducing drugs that are currently available. An additional benefit to postmenopausal women of these drugs is that they may reduce the risk of osteoporosis and resultant fractures by stimulating bone growth. The statins are currently the most potent drugs available for lowering cholesterol levels.
Other drugs, such as Questran® and Colestid®, lower cholesterol by causing the body to increase the conversion of cholesterol to bile acids that are subsequently excreted. The B vitamin niacin may also be used to lower cholesterol, but due to its high tendency to cause severe flushing and itching, many people cannot tolerate it. Even though it is a vitamin it can have some serious side effects at the doses needed to lower cholesterol, so people receiving niacin should be supervised by a physician.
Evolve® and Cardiem® are two OTC supplements made from rice bran oil that lower cholesterol. They contain a tocotrienol that has activity similar to vitamin E. They act like the statins in decreasing the synthesis of cholesterol by the body. Although they appear to be effective, long-term studies are needed to prove their safety and effectiveness.
Other drugs, such as Questran® and Colestid®, lower cholesterol by causing the body to increase the conversion of cholesterol to bile acids that are subsequently excreted. The B vitamin niacin may also be used to lower cholesterol, but due to its high tendency to cause severe flushing and itching, many people cannot tolerate it. Even though it is a vitamin it can have some serious side effects at the doses needed to lower cholesterol, so people receiving niacin should be supervised by a physician.
Evolve® and Cardiem® are two OTC supplements made from rice bran oil that lower cholesterol. They contain a tocotrienol that has activity similar to vitamin E. They act like the statins in decreasing the synthesis of cholesterol by the body. Although they appear to be effective, long-term studies are needed to prove their safety and effectiveness.
Garlic
Many alternative medicine advocates or folkloric remedies recommend garlic to lower cholesterol. In the U.S. all nutraceuticals (food substances used for their pharmacological or drug effects), such as garlic supplements, are not regulated as drugs so scientific data supporting claims are not always available. Rigid quality control standards are not required for nutriceuticals and marked variability can occur in the potency and the purity of these products.
Although garlic seems to inhibit cholesterol synthesis by the body, recent studies suggest that garlic supplements may not lower cholesterol. Garlic is composed of many sulfur containing compounds, including allinin. When garlic is crushed, allinin is converted to allicin and it is the allicin that effects cholesterol synthesis. In addition to the variability of allinin content, supplements do not contain all of the compounds found in fresh garlic. Therefore, it is not known if consumption of fresh garlic is required to have a cholesterol lowering effect.
Garlic used for cooking is generally safe, but large amounts in supplements can increase the effects of anticoagulants (blood thinners), therefore increasing the tendency for bleeding and can also interfere with blood sugar control in diabetics. Further studies are required before conclusions can be made.
Although garlic seems to inhibit cholesterol synthesis by the body, recent studies suggest that garlic supplements may not lower cholesterol. Garlic is composed of many sulfur containing compounds, including allinin. When garlic is crushed, allinin is converted to allicin and it is the allicin that effects cholesterol synthesis. In addition to the variability of allinin content, supplements do not contain all of the compounds found in fresh garlic. Therefore, it is not known if consumption of fresh garlic is required to have a cholesterol lowering effect.
Garlic used for cooking is generally safe, but large amounts in supplements can increase the effects of anticoagulants (blood thinners), therefore increasing the tendency for bleeding and can also interfere with blood sugar control in diabetics. Further studies are required before conclusions can be made.
Fiber & Whole Grains
The FDA allows health claims to be placed on foods that contain at least 51% whole grains (whole wheat, whole oats, corn, barley, and rice) stating that they reduce the risk of heart disease. The fiber in the grain appears to provide the benefits. Psyllium acts by inhibiting absorption of dietary cholesterol. The effects on cholesterol levels are generally modest. Oat bran acts in a similar manner but is more effective at lowering cholesterol than psyllium.
Vitamin E
Vitamin E has been used for its cardioprotective effect due to its ability to prevent oxidation (antioxidant) reactions. Part of the damage to blood vessels associated with high cholesterol is due to the oxidation of LDL and the action of oxidative enzymes. Vitamin E is thought to be able to slow or reverse this process.
Several recent studies have not seen a cardioprotective effect of vitamin E, but this may be due to the dose used or the possibility that combination antioxidants may be needed to see this effect. For example, vitamin C may be necessary to keep the vitamin E in an antioxidant form. Vitamin E is well tolerated, but at high doses it can increase the risk of bleeding associated with anticoagulants (blood thinners).
Several recent studies have not seen a cardioprotective effect of vitamin E, but this may be due to the dose used or the possibility that combination antioxidants may be needed to see this effect. For example, vitamin C may be necessary to keep the vitamin E in an antioxidant form. Vitamin E is well tolerated, but at high doses it can increase the risk of bleeding associated with anticoagulants (blood thinners).
Homocycteine
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| High Cholesterol |
Homocysteine levels may be an inherited trait, or may be associated with renal failure, psoriasis, certain leukemias, folate, B6 or B12 deficiencies or certain drugs. The AHA recommends consuming at least 400 mcg of folic acid per day. People with elevated homocysteine levels will require higher amounts. Adequate folic acid consumption is important in pregnancy in order to decrease the chances of the baby developing neural tube defects. People with elevated homocysteine levels will require higher amounts.
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