What is Cholesterol?
What Causes High Cholesterol?
Cholesterol is a lipid (fat) which is produced by the liver.
Cholesterol is vital for normal body function.
Every cell in our body has cholesterol in its outer
layer.
Cholesterol is a waxy steroid and is transported in the blood plasma of all animals.
Cholesterol is a waxy steroid and is transported in the blood plasma of all animals.
It is the main sterol synthesized by
animals - small amounts are also synthesized in plants and fungi.
A sterol is a steroid sub-group.
The word "cholesterol" comes from the Greek word chole, meaning "bile", and the Greek word stereos, meaning "solid, stiff".
The word "cholesterol" comes from the Greek word chole, meaning "bile", and the Greek word stereos, meaning "solid, stiff".
What are
the functions of cholesterol?
·It builds and maintains cell membranes
(outer layer), it prevents crystallization of hydrocarbons in the membrane
·It is essential for determining which
molecules can pass into the cell and which cannot (cell membrane permeability)
·It is involved in the production of
sex hormones (androgens and estrogens)
·It is essential for the production of
hormones released by the adrenal glands (cortisol, corticosterone, aldosterone,
and others)
·It aids in the production of bile
·It converts sunshine to vitamin D. Scientists from the Rockefeller
University were surprised to find that taking vitamin D supplements do not seem to reduce the risk
of cholesterol-related cardiovascular disease.
·It insulates nerve fibers
There are three main types of lipoproteins
Cholesterol
is carried in the blood by molecules called lipoproteins.
A lipoprotein is any complex or compound
containing both lipid (fat) and protein.
The three main types
are:
·LDL (low density
lipoprotein) - people often refer to it as bad cholesterol. LDL
carries cholesterol from the liver to cells. If too much is carried, too much
for the cells to use, there can be a harmful buildup of LDL. This lipoprotein
can increase the risk of arterial disease if levels rise too high. Most human
blood contains approximately 70% LDL - this may vary, depending on the person.
·HDL (high density
lipoprotein) - people often refer to it as good cholesterol.
Experts say HDL prevents arterial disease. HDL does the opposite of LDL - HDL
takes the cholesterol away from the cells and back to the liver. In the liver
it is either broken down or expelled from the body as waste.
·Triglycerides - these are
the chemical forms in which most fat exists in the body, as well as in food.
They are present in blood plasma. Triglycerides, in association with
cholesterol, form the plasma lipids (blood fat). Triglycerides in plasma
originate either from fats in our food, or are made in the body from other
energy sources, such as carbohydrates. Calories we consume but are not used
immediately by our tissues are converted into triglycerides and stored in fat
cells. When your body needs energy and there is no food as an energy source,
triglycerides will be released from fat cells and used as energy - hormones
control this process.
What are normal cholesterol levels?
The
amount of cholesterol in human blood can vary from 3.6 mmol/liter to 7.8
mmol/liter.
The National Health Service (NHS), UK,
says that any reading over 6 mmol/liter is high, and will significantly raise
the risk of arterial disease. The UK Department of Health recommends a target
cholesterol level of under 5 mmo/liter. Unfortunately, two-thirds of all UK
adults have a total cholesterol level of at least five (average men 5.5,
average women 5.6).
Below is a list of cholesterol levels and how most doctors would categorize them in mg/dl (milligrams/deciliter) and 5mmol/liter (millimoles/liter).
Below is a list of cholesterol levels and how most doctors would categorize them in mg/dl (milligrams/deciliter) and 5mmol/liter (millimoles/liter).
·Desirable - Less than 200 mg/dL
·Bordeline high - 200 to 239 mg/dL
·High - 240 mg/dL and above
·Optimum level: less than 5mmol/liter
·Mildly high cholesterol level: between
5 to 6.4mmol/liter
·Moderately high cholesterol level:
between 6.5 to 7.8mmol/liter
·Very high cholesterol level: above
7.8mmol/liter
Dangers of high cholesterol levels
High cholesterol levels can cause:
·Atherosclerosis - narrowing
of the arteries.
·Higher coronary heart
disease risk
- an abnormality of the arteries that supply blood and oxygen to the heart.
·Heart attack - occurs
when the supply of blood and oxygen to an area of heart muscle is blocked,
usually by a clot in a coronary artery. This causes your heart muscle to die.
·Angina - chest
pain or discomfort that occurs when your heart muscle does not get enough blood.
·Other cardiovascular
conditions
- diseases of the heart and blood vessels.
·Stroke and mini-stroke - occurs
when a blood clot blocks an artery or vein, interrupting the flow to an area of
the brain. Can also occur when a blood vessel breaks. Brain cells begin to die.
If both blood cholesterol and
triglyceride levels are high, the risk of developing coronary heart disease
rises significantly.
Symptoms of high cholesterol (hypercholesterolaemia)
Symptoms of high cholesterol (hypercholesterolaemia)
Symptoms
of high cholesterol do not exist alone in a way a patient or doctor can
identify by touch or sight.
Symptoms of high cholesterol are
revealed if you have the symptoms of atherosclerosis,
a common consequence of having high cholesterol levels.
These
can include:
·Narrowed coronary arteries in the
heart (angina)
·Leg pain when exercising - this is
because the arteries that supply the legs have narrowed.
·Ruptured plaques - this can
lead to coronary thrombosis (a clot forming in one of the arteries that
delivers blood to the heart). If this causes significant damage to heart muscle
it could cause heart failure.
·Xanthomas - thick
yellow patches on the skin, especially around the eyes. They are, in fact,
deposits of cholesterol. This is commonly seen among people who have inherited
high cholesterol susceptibility (familial or inherited hypercholesterolaemia).
What causes high cholesterol?
Lifestyle causes
·Nutrition - although
some foods contain cholesterol, such as eggs, kidneys, eggs and some sea foods,
dietary cholesterol does not have much of an impact in human blood cholesterol
levels. However, saturated fats do! Foods high in saturated fats include red
meat, some pies, sausages, hard cheese, lard, pastry, cakes, most biscuits, and
cream (there are many more).
·Sedentary lifestyle - people
who do not exercise and spend most of their time sitting/lying down have
significantly higher levels of LDL (bad cholesterol) and lower levels of HDL
(good cholesterol).
·Bodyweight - people
who are overweight/obese are much more likely to have higher LDL levels and
lower HDL levels, compared to people who are of normal weight.
·Smoking - this can
have quite a considerable effect on LDL levels.
·Alcohol - people
who consume too much alcohol regularly, generally have much higher levels of
LDL and much lower levels of HDL, compared to people who abstain or those who
drink in moderation.
Treatable medical conditions
These medical conditions are known to cause LDL levels to rise. They are all conditions which can be controlled medically (with the help of your doctor, they do not need to be contributory factors):
These medical conditions are known to cause LDL levels to rise. They are all conditions which can be controlled medically (with the help of your doctor, they do not need to be contributory factors):
·High levels of triglycerides
·Kidney diseases
·Liver diseases
·Under-active thyroid gland
Risk factors which cannot be treated
These are known as fixed risk factors:
These are known as fixed risk factors:
·Your genes 1 - people
with close family members who have had either a coronary heart disease or a
stroke, have a greater risk of high blood cholesterol levels. The link has been
identified if your father/brother was under 55, and/or your mother/sister was
under 65 when they had coronary heart disease or a stroke.
·Your genes 2 - if you
have/had a brother, sister, or parent with hypercholesterolemia (high
cholesterol) or hyperlipidemia (high blood lipids), your chances of having high
cholesterol levels are greater.
·Your sex - men have
a greater chance of having high blood cholesterol levels than women.
·Your age - as you
get older your chances of developing atherosclerosis increase.
·Early menopause - women
whose menopause occurs early are more susceptible to
higher cholesterol levels, compared to other women.
·Certain ethnic groups - people
from the Indian sub-continent (Pakistan, Bangladesh, India, Sri Lanka) are more
susceptible to having higher cholesterol levels, compared to other people.
How is high cholesterol diagnosed?
Cholesterol
levels may be measured by means of a simple blood test. It is important not to
eat anything for at least 12 hours before the blood sample is taken. The blood
sample can be obtained with a syringe, or just by pricking the patient's
finger.
The blood sample will be tested for LDL and HDL levels, as well as blood triglyceride levels. The units are measure in mg/dl (milligrams/deciliter) or 5mmol/liter (mill moles/liter).
Researchers at the Sree Sastha Institute of Engineering and Technology, India, developed a photographic cholesterol test, which they describe as a completely non-invasive way to test cholesterol levels.
People who have risk factors should consider having their cholesterol levels checked.
The blood sample will be tested for LDL and HDL levels, as well as blood triglyceride levels. The units are measure in mg/dl (milligrams/deciliter) or 5mmol/liter (mill moles/liter).
Researchers at the Sree Sastha Institute of Engineering and Technology, India, developed a photographic cholesterol test, which they describe as a completely non-invasive way to test cholesterol levels.
People who have risk factors should consider having their cholesterol levels checked.
What are the treatments for high cholesterol?
Lifestyle
Most people, especially those whose only risk factor has been lifestyle, can generally get their cholesterol and triglyceride levels back to normal by:
Most people, especially those whose only risk factor has been lifestyle, can generally get their cholesterol and triglyceride levels back to normal by:
·Doing plenty of exercise
·Eating plenty of fruits, vegetables,
whole grains, oats, good quality fats
·Avoiding foods with saturated fats
·Getting plenty of sleep (8 hours each
night)
·Bringing your bodyweight back to
normal
·Avoiding alcohol
·Stopping smoking
Many experts say that people who are at
high risk of developing cardiovascular disease will not lower their risk just
by altering their diet. Nevertheless, a healthy diet will have numerous health
benefits.
Cholesterol-controlling medications
If your cholesterol levels are still high after doing everything mentioned above, your doctor may prescribe a cholesterol-lowering drug. They may include the following:
Cholesterol-controlling medications
If your cholesterol levels are still high after doing everything mentioned above, your doctor may prescribe a cholesterol-lowering drug. They may include the following:
·Statins (HMG-CoA
reductase inhibitors) - these block an enzyme in your liver that
produces cholesterol. The aim here is to reduce your cholesterol levels to
under 4 mmol/liter and under 2 mmol/liter for your LDL.
Statins are
useful for the treatment and prevention of atherosclerosis.
2. fluvastatin,
3. lovastatin,
4. pravastatin,
6.
simvastatin
are examples
of statins.
·Aspirin - this
should not be given to patients under 16 years of age.
·Drugs to lower triglyceride
levels
- these are fibric acid derivatives and include
1.
gemfibrozil,
3.
clofibrate.
·Niacin - this is a
B vitamin that exists in various foods. You can only get very high doses with a
doctor's prescription.
Niacin
brings down both LDL and HDL levels.
Side effects
might include itching, headaches, hot flashes (UK: flushes), and tingling
(mostly very mild if they do occur).
·Anti hypertensive drugs - if you
have high blood pressure your doctor may prescribe
1.
Angiotensin-converting enzyme (ACE)
inhibitors,
2.
Angiotensin || receptor blockers (ARBs),
3.
Diuretics,
4.
Beta-blockers,
5.
Calcium channel blockers.
In
some cases cholesterol absorption inhibitors (ezetimibe) and bile-acid sequestrants
may be prescribed.
They have more side effects and require
considerable patient education to achieve compliance (to make sure drugs are
taken according to instruction).
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