heart and blood vessel disorders
Atherosclerosis
Risk Factors for Atherosclerosis
Some risk factors for atherosclerosis can be modified (can be changed by the person) (see also Prevention ). Modifiable risk factorsinclude Tobacco use High levels of cholesterol in the blood High blood pressure Diabetes Obesity Physical inactivity Low daily consumption of fruits and vegetables Risk factors that cannot be modifiedinclude Having a family history of early atherosclerosis (that is, having a close male relative who developed the disease before age 55 or having a close female relative who developed the disease before age 65) Advancing age Male sex There are many risk factors that are still being studied, such as high levels of C-reactive protein (an inflammatory protein) in the blood, high levels of some components of cholesterol such as apolipoprotein B or lipoprotein(a), and psychosocial factors (such as anxiety and low socioeconomic status). One of the most important modifiable risk factors is smoking. (Using other forms of tobacco, such as snuff and chewing tobacco, also increases risk.) A smoker‘s risk of developing some forms of atherosclerosis such as is directly related to the amount of tobacco smoked daily. The risk of a Tobacco use decreases the level of high-density lipoprotein (HDL) cholesterol—the “good” cholesterol—and increases the level of low-density lipoprotein (LDL) cholesterol—the “bad” cholesterol. Smoking increases the level of carbon monoxide in the blood, which may increase the risk of injury to the lining of the artery‘s wall. Tobacco use causes arteries already narrowed by atherosclerosis to constrict, further decreasing the amount of blood reaching the tissues. In addition, tobacco use increases the blood's tendency to clot (by making platelets stickier), so that it increases the risk of Overview of Peripheral Arterial Disease (atherosclerosis affecting arteries other than those that supply the heart and brain), People who quit using tobacco have only half the risk of those who continue to use tobacco—regardless of how long they smoked before quitting. Quitting also decreases the risk of death after coronary artery bypass surgery or a heart attack and the risk of illness and death in people who have peripheral arterial disease. The benefits of quitting tobacco use begin immediately and increase with time. Secondhand smoke (smoke breathed in from someone else‘s smoking) appears to increase risk also. It should be avoided. Smoking is an important risk factor for atherosclerosis. A high level of LDL cholesterol is another important modifiable risk factor. A diet that is high in saturated fats (see Types of Fat ) causes LDL cholesterol levels to increase in susceptible people. Cholesterol levels also increase as people age and are normally higher in men than in women, although levels increase in women after menopause. Several hereditary disorders result in high levels of cholesterol or other fats. People with these hereditary disorders can have extremely high levels of LDL cholesterol and (if untreated) die of coronary artery disease at an early age. In addition, lipoprotein(a) is an unusual hereditary cholesterol-containing particle that also contributes to heart attacks and strokes. Lowering high LDL cholesterol levels through the use of drugs can significantly reduce the risk of heart attacks, strokes, and death. Many types of lipid-lowering drugs are available (see table Lipid-Lowering Drugs ). Statins are the most common type. Not all high cholesterol levels increase the risk of atherosclerosis. A high level of HDL (good) cholesterol decreases the risk of atherosclerosis. The desired level of total cholesterol, which includes LDL cholesterol, HDL cholesterol, and triglycerides, is 140 to 200 mg/dL (3.6 to 5.2 mmol/L). Risk of a heart attack more than doubles when the total cholesterol level approaches 300 mg/dL (7.8 mmol/L). The risk is decreased when the LDL cholesterol level is below 130 mg/dL (3.4 mmol/L), and the HDL cholesterol level is above 40 mg/dL (1 mmol/L). For lipoprotein(a), levels above 50 mg/dL (100 nmol/L) are associated with an increased risk of heart disease. High-risk people, such as those who have diabetes or atherosclerotic heart disease or have had a heart attack, stroke, or bypass surgery, benefit from high doses of statins to lower their LDL cholesterol as much as possible. High triglyceride levels are often associated with low HDL cholesterol levels. However, evidence suggests that high triglyceride levels alone may also slightly increase the risk of atherosclerosis. Uncontrolled High Blood Pressure is a risk factor for heart attack and stroke, which are caused by atherosclerosis. The risk of cardiovascular disease starts increasing when blood pressure levels are above 110/75 mm Hg. Reducing high blood pressure clearly lowers risk. Doctors usually try to achieve a blood pressure of less than 140/90 mm Hg, and often less than 130/80 mm Hg in people at risk of cardiovascular disease, such as people with diabetes or kidney disease. People who have Diabetes Mellitus (DM) tend to develop disease that affects small arteries, such as those in the eyes, nerves, and kidneys, leading to vision loss, nerve damage, and Obesity , particularly abdominal (truncal) obesity, increases the risk of Physical inactivity appears to increase the risk of developing coronary artery disease, and much evidence suggests that regular exercise even to a moderate degree reduces this risk and decreases mortality. Exercise can also help modify other risk factors for atherosclerosis—by lowering blood pressure and cholesterol levels and by helping with weight loss and decreasinginsulinresistance. There is substantial evidence that regular vegetable and fruit consumption can decrease the risk of coronary artery disease. It is unclear whether fruits and vegetables appear beneficial due to the substances (phytochemicals) they contain, or whether people who eat a lot of fruits and vegetables also eat less saturated fat and are more likely to take fiber and vitamins. However, phytochemicals called flavonoids (in red and purple grapes, red wine, black teas, and dark beers) appear especially protective. High concentrations in red wine may help explain why the French have a relatively low incidence of coronary artery disease, even though they use more tobacco and consume more fat than Americans do. But no studies prove that eating flavonoid-rich foods or using supplements instead of foods prevents atherosclerosis. Increased fiber content in certain vegetables may decrease total cholesterol and may decrease blood glucose andinsulinlevels. However, excessive fiber interferes with the absorption of certain minerals and vitamins. In general, foods rich in phytochemicals and vitamins are also rich in fiber. Fat is an essential part of the diet. The notion that eating less fat is important to a healthy diet is only partly true because the type of fat also matters. The main types of fats are Saturated and trans fats Unsaturated fats (polyunsaturated and monounsaturated—see Types of Fat ) Fats may be soft (or liquid) or firm at room temperature. Soft fats, such as oils and some margarines, tend to be higher in polyunsaturated and monounsaturated fats. Hard fats, such as butter and shortening, tend to be higher in saturated and trans fats. Saturated and trans fats are more likely to cause atherosclerosis. Thus, whenever possible, people should limit the amount of saturated and trans fats in their diet and choose foods with monounsaturated or polyunsaturated fats instead. Saturated and trans fats are found in red meat, many fast food and junk food items, full-fat dairy products (such as cheese, butter, and cream), and hard (stick) margarines. However, the evidence regarding dangers of natural trans fats remains unclear. Monounsaturated fats are found in canola and olive oil, soft margarines with no trans fat, nuts, and olives. Polyunsaturated fats are found in nuts, seeds, oils, and mayonnaise. Two types of polyunsaturated fats—omega-3 and omega-6 fats—are essential to a healthy diet. Omega-3 fats are found in fatty fish such as salmon, omega-3 eggs, canola oil, and walnuts. Omega-6 fats are found in some nuts and seeds and in safflower, sunflower, and corn oils. Eating a healthy diet can help decrease the risk of atherosclerosis. However, it is less clear whether supplementing the diet with vitamins, phytochemicals, trace minerals, or coenzyme Q10 also helps reduce the risk. Alcohol increases the level of HDL cholesterol (good cholesterol), and it also decreases the risk of blood clots and inflammation and helps protect the body from the by-products of cell activity. However, more than moderate alcohol consumption (more than 14 drinks per week for men and more than 9 drinks per week for women) can cause significant health problems and increase the risk of death. People who drink greater amounts of alcohol should cut back. People who do not drink alcohol should not start. 