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Facts About Cholesterol

Cholesterol is a special kind of fat, which is an essential structural component of cell membranes - ensuring proper membrane permeability and fluidity (1).

Cholesterol is produced in your body and is a precursor of important substances such as the steroid hormones, sex hormones, bile acids, and vitamin D.

A person of average weight synthesizes about 1 g of cholesterol in the body each day. The total body content of cholesterol is about 35 g - mainly located in the cell membranes.

The amount of synthesized cholesterol in the body depends on the amount absorbed from the diet. If much is absorbed from the diet, synthesis in the body decreases. If little is absorbed, synthesis in the body increases.

Therefore, cholesterol intake in food has little effect on total body cholesterol content or concentrations of cholesterol in the blood.

Since cholesterol is insoluble in blood, it is transported in the circulatory system within lipoproteins.

There are several types of lipoproteins called, in order of increasing density, chylomicrons, very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) .

The different lipoproteins contain apolipoproteins, which serve as ligands (binding molecules) for specific receptors on cell membranes. In this way, the lipoprotein particles are molecular addresses that determine the endpoints for cholesterol transport.

HDL cholesterol is a powerful antioxidant. It scavenges free radicals and prevent oxidative damage in the system. Hence the term “good cholesterol” for HDL cholesterol.

Atherosclerosis

For many years cholesterol has been considered the obvious cause of atherosclerosis The atherosclerotic lesion(arteriosclerotic vascular disease or ASVD).

This is a condition in which arterial walls react to injury with chronic inflammation with accumulation of white blood cells and low-density lipoproteins (LDL) containing cholesterol. Hence the term “bad cholesterol” for LDL cholesterol.

Such formation of atherosclerotic plaques (see picture) leads to narrowing and stiffening of the arteries and may be complicated by thrombosis formation, which in turn may cause myocardial infarction (heart attack) or stroke.

The presence of LDL cholesterol in the inflammatory atherosclerotic plaques led to the hypothesis that elevated cholesterol concentration in the blood is the cause of atherosclerosis. It has even been postulated that the more LDL there is in the blood, the more rapidly atherosclerosis develops.  

Does it help to lower cholesterol in the blood?

A total of 22 controlled clinical trials including 127,116 individuals have studied the effect of lowering cholesterol in the blood using drugs or diet. The very clear overall result was that lowering cholesterol does not reduce total mortality or mortality from coronary heart disease (2).   

It has also been shown that the degree of atherosclerosis, and atherosclerotic growth, are independent of the concentration or the change of LDL-cholesterol in almost all studies performed (3).

In recent years the effects of statins have been studied (4). Statins are drugs that can lower cholesterol levels by inhibiting its production.

In people with established coronary heart disease (CHD), statins have a slight effect in reducing the risk of subsequent heart attacks (secondary prevention). Whether statins can prevent coronary heart disease and stroke in people with elevated cholesterol levels but without signs of any such disease (primary prevention) is questionable.   

Statins can have severe adverse effects, particularly muscle damage. Other possible adverse effects include cognitive loss, neuropathy, pancreatic and hepatic dysfunction, and sexual dysfunction. Furthermore, statins may cause diabetes mellitus, which is a risk factor for atherosclerosis (se below). Some doctors believe statins are overprescribed.

Futhermore, the effect of the statins on cardiovascular disease seems not clearly associated with the cholesterol lowering effect. It seems that the statins work mainly by improving endothelial function and modulating the inflammatory response in the atherosclerotic plaques.

In fact cholesterol may have a protective anti-infectious effect as supported by highly significant inverse correlations between total-cholesterol concentration in the blood and mortality from infectious causes (5).

Indeed a high cholesterol concentration in the blood may be an attempt to combat inflammatory processes in the body including those taking place in the atherosclerotic plaques.

Thus an elevated cholesterol may be an effect of atherosclerosis rather than its cause.

At this time there seems to be increasing evidence that the cause of atherosclerosis may be infection (6).

Factors associated with atherosclerosis

The most important risk factors for atherosclerosis are:

• diabetes mellitus (the elevated and varying blood sugar                  concentrations damage the vascular lining)

• high blood concentration of LDL (however, as decribed this may be an                effect of atherosclerosis)

• low blood concentration of HDL (however, this could also be an effect                of atherosclerosis)

• tobacco smoking (substances in the smoke damage the vascular                 lining)

• hypertension (elevated blood pressure - damages the vascular lining)

• elevated blood C-reactive protein (CRP) concentrations (indicative of                inflammation)

• advanced age

• male gender

• atherosclerosis in the close family

Damage of the vasular lining may facilitate an infection being established in the arteries.

How to prevent atherosclerosis

First of all you should try to reduce the risk factors mentioned above. You can reduce the risk of type 2 diabetes mellitus by cutting carbohydrate and avoiding being overweight. Abstaining from tobacco smoking and having an elevated blood pressure treated are also important.

Any signs of chronic infection should be treated with adequate antimicrobial therapy.

A certain amount of exercise and sufficient amounts of protein, essential fatty acids, vitamins and minerals are also important.  

Don’t be an anti-cholesterol fanatic. Cholesterol is necessary for your body. It is even produced in the body, where - as previously mentioned - it has very important functions.


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