Cholesterol
 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 levels 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
recommend cholesterol screening every five years for people 20
year 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 for 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) |
|
20-29 |
<180 |
>200 |
>220 |
|
30-39 |
<200 |
>220 |
>240 |
|
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 advise 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 advise 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.
Limitations
The problem with these guidelines and with looking at total
cholesterol alone is that they makes 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 are 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).
C-Reactive Protein
A blood test called 'high-sensitive C-reactive protein' (HS
CRP) can measure your C-reactive protein level, which is an index
of chronic inflammation and may be an even greater predictor
of risk than LDL cholesterol. Chronic
inflammation increases risk of coronary heart disease and other
disorders. (Ridker 2007)
|
CVD Risk: |
Low |
Intermediate |
High |
|
CRP Level (mg/l) |
<1 |
1-3 |
>3 |
References
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. 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.
Ridker PM, JE Buring, N Rifai, NR Cook (2007). Development
and validation of improved algorithms for the assessment of global
cardiovascular risk in women: The Reynolds Risk Score. JAMA 297(6),
611-19.
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.
|
