Cholesterol is a waxy, fat like substance classified as a waxy steroid of fat. It is vital structural component of cell membranes, required for cell function. Cholesterol is also used for the production of steroid hormones, bile acids, and Vitamin D.
Blood cholesterol level is considered an indicator of those individuals that are prone to coronary heart disease. The build-up of cholesterol in the artery form plaque that may lead to narrowing (high blood pressure) or complete blockage (heart attack or stroke) of the vessel. Interestingly, Garret (1964) found no correlation between either dietary cholesterol or blood cholesterol levels and severity of atherosclerosis in patients receiving surgical treatment for atherosclerotic vascular disease.
To suggest reducing cholesterol to fight heart disease is like proposing to reduce the number of emergency 911 phone calls to fight crime, since 911 calls are related to the incidence of crime. Even if there were a strong relationship between cholesterol and heart disease, a relationship does not imply causality. Elevated blood cholesterol appears to be a reaction to chronic inflammation rather than a cause of cardiovascular disease.
Substantially elevated blood cholesterol is certainly a health concern, but lowering blood cholesterol or having too low of blood cholesterol is associated with other health risks. For example, low serum cholesterol or lowering serum cholesterol concentrations by diet, drugs, or both may increase risk of deaths due to suicide or violence (Engleberb 1992, Golomb 1998 & 2000, Colin 2003). It is thought that low cholesterol decreases the number of serotonin receptors in the brain. One of the functions of serotonin in the central nervous system is the suppression of aggressive impulses.
Total Cholesterol Standards
Total cholesterol after a 12 hour fast is used to screen and assess risk of coronary heart disease. The American Heart Association recommends cholesterol screening every five years for people 20 years or older.
The standards suggest if levels rise above 180 mg/dl, the risk for developing coronary heart disease increases. A cholesterol value of 220 mg/dl correlates to nearly a two-fold elevation in incidence of coronary heart disease as compared to 180 mg/dl. A reduction of 1% is shown to reduce the risk of coronary artery disease by 2% for levels over 200 mg/dl.
The following chart lists accepted values and risk levels for total cholesterol for men and women in the various age groups:
|Age||Goal||Moderate Risk||High Risk|
|(75th Percentile)||(90th Percentile)|
|40 and over||<200||>240||>260|
These are recommendations of the National Cholesterol Education Program (National Institutes of Health) :
|Classifications of total cholesterol||Recommendation|
|Acceptable||less than 200 mg/dL||Have test repeated every five years|
|Borderline high||200-239 mg/dL||If you have two other heart disease risk factors (see below), you should have your physician do a complete lipid profile and get medical advice based on that test.|
|If you have no other risk factors, you improve your diet and have another screening within a year.|
|High||240 mg/dL and above||You should see a physician within two months of screening for medical advice and treatment.|
Heart disease risk factors which can be changed include high blood cholesterol, high blood pressure, cigarette smoking, obesity, and sedentary lifestyle. Those risk factors which cannot be changed include family history, gender and advancing age (men >45; women >55). Diabetes is a risk factor that in some cases can be changed or controlled.
The problem with these guidelines and with looking at total cholesterol alone is that they make no distinction between HDL and small LDL. For example a total cholesterol reading of 240 could conceivably be considered healthy if the ratio of lipids is favorable. Furthermore, focusing on cholesterol in general does not measure the underlining cause of plaque build up.
In the Framingham study, 80% of the subjects who later went on to have Cardiovascular Disease had the same total cholesterol concentrations as those who did not (Superko 2002).
Colin A, Reggers J, Castronovo V, Ansseau M (2003). Lipids, depression and suicide. Encephale. 29(1), 49-58.
Engelberg H (1992). Low serum cholesterol and suicide. Lancet. 339(8795), 727-9.
Golomb BA (1998). Cholesterol and violence: is there a connection? Ann Intern Med. 128(6), 478-87.
Golomb BA, Stattin H, Mednick S (2000). Low cholesterol and violent crime. J Psychiatr Res. 34(4-5), 301-9.
Superko HR, Nejedly M, Garrett B (2002). Small LDL and its clinical importance as a new CAD risk factor: a female case study. Prog Cardiovasc Nurs. 17, 167–73.