Is Cholesterol Bad for Health?
Should This Vital Substance be Eliminated From the Diet?
Oct 21, 2009
Almost everyone seems to know about cholesterol. Middle aged adults are especially encouraged to get their blood cholesterol levels checked because too much circulating cholesterol is bad for your heart. This represents the view of the majority of doctors involved in the treatment of heart disease.
The Role of Cholesterol
Cholesterol is a vital component in the body. It forms the basis of the steroid hormones and is essential for building cell membranes and the myelin sheath that provides the insulation for nerves.
Cholesterol is transported around the body attached to carrier molecules called lipoproteins. Low-density lipoproteins (LDL) carry the most and have a tendency to deposit cholesterol where it isn't wanted – the arterial walls, for example. High density lipoproteins (HDL) take cholesterol away from the blood and back to the liver and so help reduce cholesterol deposits; hence, HDL and LDL are called good and bad cholesterol respectively.
Cholesterol and Coronary Vascular Disease
Most heart disease and cases of stroke can be attributed to atherosclerosis: the build up of fatty deposits (atheromatic plaques), including cholesterol, on arterial walls. This deposit causes narrowing of the blood vessels and slowing down the flow of blood. This in turn tends to promote clotting and the formation of blood clots which may completely block blood flow.
When this happens in arteries supplying the heart, the cardiac muscles are starved of oxygen and a heart attack results. If the same thing occurs in an artery supplying the brain, then a stroke occurs.
As a good deal of the atheromatic material contains cholesterol, the theory goes that high cholesterol in the blood tends to promote the formation of these deposits.
Framingham Heart Study
Some of the earliest evidence linking cholesterol levels to heart attack and stroke came from an epidemiological study on 5000 residents of the town of Framingham in Massachusetts USA.
The study, which started in 1948 and is still going, has provided much valuable information on the relationships between lifestyle, medication and biochemical parameters and cardiovascular disease. Many, but not all, of the findings from this ongoing research have been supported by other studies.
Controlling Cholesterol
The Framingham study has indirectly generated many millions of dollars. The food industry cottoned on to the fact some cholesterol comes from the diet and this stimulated heavy marketing of low-fat, low-cholesterol foods, a move supported by most Western governments anxious to see reductions in cardiovascular disease and obesity.
A further boost for the food industry came with the introduction of foods – spreads and yoghurt mostly – which contain plant compounds that bind cholesterol in the gut and stop it being absorbed.
Patients who are thought to be at greater risk of heart disease or stroke – and this for some doctors means all middle aged adults - are recommended to take low-fat foods and or cholesterol lowering foods, along with increasing exercise which also helps lower cholesterol.
However, since most of the cholesterol in the body is made by the liver and is not delivered in the diet, these approaches are only likely to be partially effective. For the definitive cholesterol-lowering agent, the statin drugs have been developed.
Statins and Cholesterol
Statins are a class of drugs that inhibit the production of cholesterol by the liver. Statins are popular with doctors and governments. They have been shown to reduce the risk of cardiovascular disease in middle aged men. Their effectiveness in women has been questioned . Like all drugs, they have side effects, sometimes causing pain in some and muscle destruction in a few.
The orthodox view on the prevention of cardiovascular disease is that statins should be used extensively to lower cholesterol levels. In the UK, statins are now available over the counter.
The Alternative View
Although the majority of doctors see a very clear connection between cholesterol levels and cardiovascular disease not all of them do so: some experts are skeptical about the cholesterol hypothesis.
One of the leading figures in the "cholesterol skeptic" movement is Dr. Uffe Ravnskov, who works in Sweden. He and others dispute the conclusions drawn from the Framingham study and the related subsequent work, usually citing methodological flaws as the basis for their criticism.
Ravnskov believes that atheromatic plaque formation is part of an inflammatory process possibly stimulated by infection.
Not only do the skeptics believe that there is no firm evidence to link cholesterol to cardiovascular disease, they feel it is wrong to discourage people from eating animal fats and other cholesterol containing foods such as eggs.
Because cholesterol is a vital component not only in hormone production but in the manufacture of cell membranes they believe that such dietary limitations may harm immunity and make people more prone to infections.
This article is for information only, if you have any health concerns you should consult your doctor.
Resources
www.framinghamheartstudy.org/about/background.html
www.ravnskov.nu/cholesterol.htm
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