Importance of Cholesterol
Cholesterol is both our friend as well as our enemy. At normal levels, it is an essential substance for the body’s normal functioning. But if its levels in the blood is too high, it becomes a silent danger putting us at risk of heart attack.
Cholesterol is a sterol, being oil-based and won’t mix with blood which is water-based. It is one of three major classes of lipids which all animal cells utilize to construct their membranes. It is manufactured by all animal cells. Plant cells do not manufacture cholesterol. It is also the precursor of the steroid hormones, bile acids and vitamin D.
Cholesterol, being insoluble in water, is transported in the blood plasma within protein particles (lipoproteins). Lipoproteins are classified by their density:
- Low density lipoprotein (LDL
- Intermediate density lipoprotein (IDL)
- Very low density lipoprotein (VLDL)
- High density lipoprotein (HDL).
VLDL. LDL and IDL are collectively named non-HDL cholesterol
All lipoproteins carry cholesterol. However elevated levels of the lipoproteins other than HDL, in particular LDL-cholesterol are associated with an increased risk of atherosclerosis 動脈粥樣硬化 and coronary heart disease 冠狀動脈疾病. In the contrary higher levels of HDL cholesterol are protective. Elevated levels of non-HDL cholesterol and LDL in the blood may be a consequence of diet, obesity, genetic diseases (such as LDL receptor mutations in familial hypercholesterolemia 家族性高膽固醇血症), or the presence diabetes and underactive thyroid 甲狀腺機能低下症.
Cholesterol has five major functions, without which we could not live.
- Allows the body to produce vitamin D
- Contributes to the structure of cell walls
- Enables the body to make certain hormones.
- In the brain it triggers the release of neurotransmitters 神經遞質 which effect the data-processing and memory functions. Neurotransmitters are endogenous chemicals that transmit signals across a synapse 突觸 from one neuron (brain cell) to another ‘target’ neuron. A lack of cholesterol brain is unable functioning properly
- Makes up digestive bile acids in the intestine
Muscle aches is the beginning of damage to the muscular system. A lack of cholesterol doesn’t solely effect the brain but effects the whole human body negatively. Cholesterol acts to interlock ‘lipid molecules 脂質分子,’ which stabilize cell membranes. Cholesterol is the vital building block for all body tissues. Lowering such a vital molecule is absurdity.
Cholesterol does not damage the heart nor cause heart attacks. It helps the brain functioning properly and heals from toxins and other injuries. Without adequate amounts of cholesterol we would be in trouble to remember and to think clearly. Without cholesterol our bodies do not function properly and begin to fall apart.
Cholesterol has a water-binding capacity and is very important in repairing normal skin barrier function.
Equally LDL cholesterol is needed for gaining muscle and losing weight. People often say, ‘Get rid off all bad (LDL) cholesterol,’ but in doing so, we would die. All of us need a certain amount of both LDL and HDL keeping our bodies to function correctly.
Causes of high cholesterol
High cholesterol (hypercholesterolemia/hyperlipidemia/dyslipidemia) is a major risk factor for coronary heart disease, causing heart attacks. Reducing blood lipid levels lowers cardiovascular risk.
High levels of LDL lead to build-up of cholesterol in the arteries, whereas HDL carries cholesterol to the liver for removal from the body. The build-up of cholesterol narrows arteries (atherosclerosis) in which plaques form causing restriction of blood flow.
Causes leading to high cholesterol levels – modifiable and non-modifiable risk factors are;
- Exercise and weight.
Limiting intake of fat helps managing cholesterol levels, particularly foods containing;
- Cholesterol (from animal foods, such as egg yolks, meat and cheese)
- Saturated fat (found in some meats, dairy products, chocolate, baked goods, and deep-fried and processed foods)
- Trans fat (found in some fried and processed foods).
Being overweight or obese can lead to higher blood LDL levels. Exercise can help managing this risk factor
The primary causes of hyperlipidemia are genetic – very high LDL levels are found in the inherited condition familial hypercholesterolemia 家族性高膽固醇血症. Other genetic conditions passed down from parents are: familial combined hyperlipidemia 家族性混合型高脂血症, familial dysbetalipoproteinemia 家族性血β脂蛋白異常 and familial hypertriglyceridemia 家族性高甘油三酯血症
Abnormal cholesterol levels may also be secondary to the following:
- Drugs that increase LDL cholesterol and decrease HDL cholesterol (progestins, anabolic steroids and corticosteroids)
- Liver or kidney disease
- Polycystic ovary syndrome
- Pregnancy and other conditions that increase levels of female hormones
- Underactive thyroid gland.