Cardiovascular disease, or CVD, (which includes heart disease and stroke) is a major cause of death and illness in the U.S. Important risk factors include obesity, high blood cholesterol level, high blood pressure, and type 2 diabetes. CVD is also largely preventable. Although death rates from CVD are falling, it is still a major cause of premature death. According to the American Heart Association, cardiovascular disease claimed the lives of over 800,000 people in 2006, representing 29% of all deaths in the U.S. Estimates for the year 2006 are that 81,100,000 people in the United States had one or more forms of cardiovascular disease.
What is CVD?
There are two main events that lead to CVD. The first of these is the process called atherosclerosis, which causes narrowing of the blood vessels. It happens when a type of fat in the blood called low density lipoprotein cholesterol (LDL cholesterol) accumulates and also oxidizes (becomes damaged) in the vessel walls. The walls of the blood vessel become thicker because of an overgrowth of wall tissue and an accumulation of blood clot material, forming a hardened plaque. This leads to a reduced flow of blood to the heart and may cause chest pain (angina), particularly during exercise.
The second event is called thrombosis. This is when a large blood clot forms in the vessel, sometimes as a result of the rupture of an atherosclerotic plaque, if it stops the blood supply from reaching the heart this is a heart attack. If it stops the blood supply from reaching the brain, this is a stroke. Blood clots form when cells in the blood called platelets stick together. Certain dietary factors can increase or decrease this tendency. For example, eating oily fish (eg, salmon, mackerel, sardines, herring) regularly (eg, once a week) can reduce the risk.
What is cholesterol?
Cholesterol is a type of fat that is essential for the body in small amounts. It is produced in the liver and some is also obtained from the diet. It is a constituent of cells in the body, such as brain cells. Cholesterol is carried around the body in the blood by particles called lipoproteins (for example low-density lipoprotein, LDL, and high-density lipoprotein, HDL). LDL is also often called “bad cholesterol” because high levels of LDL in the blood promote the accumulation of fat in the vessel walls. HDL is often called “good cholesterol” because it retrieves cholesterol from body’s tissues and helps to transfer it to the liver for elimination. The level of cholesterol in the blood depends partly on genetic factors but diet is also very important.