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Cholesterol Basics
Most of us know that cholesterol is something that
should be monitored because it can affect our overall health. But not everyone
remembers exactly what a healthy range is thought to be, and many never really
understood the different types.
Cholesterol is part of the way the human body is composed.
It is synthesized primarily in the liver used to form the building blocks of the
substances that compose cell membranes and certain hormones. It is integral to
many bodily functions. It is just one of the waxy substances called lipids that
are transported in the bloodstream. It must be transported out of the blood
into the cells by specialized molecules called lipoproteins. Two of these are
named the low density lipoprotein (LDL) and the high density lipoprotein (HDL),
both of which transport cholesterol of low and high density, respectively. LDL,
also called bad cholesterol, carries most of the total cholesterol in the
bloodstream and it causes problems when the concentration is too large. It then
can build up on arterial walls that lead to two vital organs, the heart and the
brain. Together with other flotsam in the blood it can form hard plaques that
can block the arteries and slow or even stop the blood flow. This condition is
called atherosclerosis. When a blockage occurs at the entry to the heart muscle
a heart attack results, and when the blood flow to the brain is interrupted a
stroke occurs. A level of LDL cholesterol in excess of 160 mg/d of blood is a
risk factor for disease. The role of the HDL, or so-called good cholesterol, is
to transport between one-third to one-fourth of total cholesterol out of the
blood and to the liver where it is excreted from the body altogether. A high
HDL level seems to protect against heart attack and a HDL level lower than 40
mg/dL in men and 50 mg/dL in women is seen as a risk factor for heart attack and
stroke.
The body generally makes the
necessary amount of cholesterol, so the amount consumed in food is usually in
excess. The foods that contain the most cholesterol are egg yolks, meat,
poultry, fish, seafood and whole-milk dairy products and their consumption
should be limited by people who have high LDL counts. Plant foods do not
contain cholesterol and need not be limited. Saturated fatty acids, as found in
animal products act to raise blood cholesterol levels, as do transfats that are
found in bakery goods, crackers and highly processed foods. The liver does
remove some of the excess cholesterol but it is recommended that the average
cholesterol intake should be less than 200 milligrams per day. Limiting the
amount of dietary fat, especially saturated fat is the key to consuming les
cholesterol.
What does this mean in terms of general health? Individuals who
maintain a total blood cholesterol of less than 200 mg/dL are at low risk for
heart attack and stroke, unless they have other risk factors, while those with
levels between 200–239 mg/dL pose a borderline high risk. Those with a total
cholesterol level of 240 mg/dL and over are at high risk of heart disease and
stroke, and must take active measures to limit their dietary intake, and perhaps
take medication as well. Triglyceride, another blood lipid should be maintained
at a level of less than 200 mg/dL . Yearly cholesterol monitoring is
recommended for those in the higher ranges. |
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