Cholesterol is regarded as a risk factor for cardiovascular diseases because high levels in the blood clog up blood vessels narrowing their lumen. They interact with fibrous tissue to form atherosclerosis (hardened cholesterol deposits) in the inner surface of the walls of blood vessels. This blocks the flow of blood to vital organs like the heart or brain, and if the blockage becomes significant, it leads to heart attack or stroke respectively.
We get our cholesterol from two sources. The body produces the cholesterol it needs from the liver for cell growth and production of certain hormones, and we also get cholesterol from animal based foods, such red meat, poultry and dairy products.
Dietary cholesterol has for long been linked with cardiovascular diseases. However recent studies are showing that dietary cholesterol may not be as significant as we once thought. More emphasis is now being placed on saturated fatty acids and trans fats. However these same substances are present in the same foods that are rich in cholesterol. When we ingest much of these fatty acids they are converted to cholesterol by the liver, which raises the blood cholesterol level.
There are two main types of cholesterol in the blood. The low-density lipoprotein (LDL) cholesterol, regarded as the bad cholesterol and the high-density lipoprotein (HDL) cholesterol, regarded as the good cholesterol. The bad cholesterol is responsible for the formation of atherosclerosis that blocks and reduces the flexibility of blood vessels. While the good cholesterol removes cholesterol from the blood and takes them to the liver for disposal.
The cardiovascular disease risk of cholesterol is not dependent only on the total cholesterol in the blood, but also the ratio of the good and the bad cholesterol in the system. This is more important. High level of bad cholesterol and low level of good cholesterol increases the risk of cardiovascular diseases, while low level of bad cholesterol and high level of good cholesterol is preferable.
Another fatty substance associated with cholesterol is triglyceride; it is also a determinant of cardiovascular diseases. It is a type of fat carried in the blood, and a high level increases the risk of cardiovascular disease, especially in association with high LDL and low HDL cholesterol.
Recommendations for blood cholesterol reduction include, eating a healthy diet, such as foods low in saturated fatty acids and trans fat. American Heart Association recommends keeping saturated fat in our diet to below 5 to 6 percent of the daily calories and avoiding trans fats as much as possible. Replace saturated fat with unsaturated fat whenever possible. Increase the fiber in our diet; these can lower cholesterol level by as much as 10%.
Examples of foods rich in saturated fat include, sweet treats and pastries such as donuts, cakes, and cookies, red meat, fatty meat, and highly processed meat, many fried foods, whole-fat dairy products such as milk, butter, cheese, and cream.
Sedentary lifestyle lowers the good cholesterol, while regular aerobic exercise lowers the bad cholesterol and blood pressure.
Smoking lowers the good cholesterol, including passive smoking. Weight gain especially if you become obese or overweight will increase your bad cholesterol and reduce your good cholesterol.