Does Cholesterol Cause Artery Disease?
Starting in the 1950’s, a raging debate began as to whether high levels of cholesterol caused heart attacks and strokes. Those involved in alternative medicine pointed to studies showing elevated rates of heart attack and stroke in people who consumed diets high in fat and cholesterol.
On the other side were conventional doctors and the FDA who adamantly proclaimed that there was no relationship between cholesterol and artery disease. The FDA actually published in the Federal Register that it was illegal to disseminate information on food labels that cholesterol was a causative factor in the development of artery disease. To document the government’s unscientific position on the cholesterol issue, we have re-printed (on the last page of this article) excerpts from what the FDA published in the Federal Register in 1959 and 1965.
Starting in the 1990’s, the dangers of high LDL-cholesterol became so apparent that the FDA backed away from interfering with companies who stated that consuming foods low in cholesterol (such as fruits, vegetables, fiber) might help prevent heart attack and stroke.(1-3)
It is now accepted that cholesterol levels above 200 increase the risk for heart attacks and strokes.(4-11) Having a cholesterol reading above 240 may be particularly dangerous. Studies dating back to the 1970’s show that maintaining high levels of beneficial HDL cholesterol may be as important as suppressing high LDL-cholesterol readings.(12-16)
The cholesterol debate, however, has carried on to this day, as newer human studies produce conflicting results as to how dangerous high cholesterol really is. There are some nutritionally-oriented doctors who think that LDL-cholesterol is not dangerous as long as it is protected against oxidation by antioxidant supplements such as vitamin E and coenzyme Q10.(17-20) Others who question the risks of high cholesterol point to studies showing that people suffering heart attacks often have normal cholesterol levels.(21-28) While there is merit to these theories, they do not justify health-conscious people ignoring high cholesterol levels.
We now know that LDL-cholesterol is only one of several known artery-disease risk factors in the blood. High levels of homocysteine, fibrinogen, triglycerides and C-reactive protein are all independent risk factors for developing a heart attack or stroke.(29-50) The presence of high levels of these other risk factors can result in a person suffering a cardiovascular event, even though their cholesterol level is low. This does not mean, however, that chronically high levels of LDL-cholesterol should be ignored.
As far as guarding against LDL-cholesterol oxidation, this may help to protect against atherosclerosis,(51) but it is still critical to keep cholesterol levels in check for those who intend to live a long and healthy life.(52) In other words, a person who takes antioxidant supplements may protect against LDL-cholesterol oxidation, but at some point, chronically high levels LDL levels could still cause a heart attack or stroke, perhaps much later in life. Evidence for this can be seen in 80-year-old people who develop coronary artery disease.(53-55) There appears to be a point in the aging process in some people when the atherosclerosis process accelerates, meaning that even slightly elevated cholesterol levels can be lethal.(56, 57)
One reason LDL-cholesterol becomes more dangerous as people age was documented in a recent study that found LDL-cholesterol is more susceptible to oxidation when there is a deficiency of DHEA. These scientists showed that DHEA is part of an integral shield against LDL oxidation and that vitamin E does not fully protect against oxidation unless adequate levels of DHEA are present. The scientists pointed out that the amount of DHEA in LDL-cholesterol “disappears to almost undetectable levels during aging.” When these scientists replaced DHEA in the LDL-cholesterol molecule, protection against oxidation was regained.(53)
A number of published studies show that people with high cholesterol who take certain cholesterol lowering drugs have a significantly lower risk of suffering a heart attack or stroke.(58) These studies cannot be ignored, as they indicate that cholesterol plays a role in the development of heart disease and stroke at least in some people.
Based on a review of all the published literature, it would appear that the ideal cholesterol level to maintain is between 180 to 200 (milligrams per deciliter of blood). Cholesterol levels above 200, increase the risk for heart attacks and strokes. (59, 60)
It is important to point out that cholesterol levels that are too low can also be lethal. An interpretation from existing published findings indicates that cholesterol levels should not drop too far below 180 in middle-aged people,(61-63) and that cholesterol levels below 150 might increase the risk of a hemorrhagic stroke (also known as a cerebral hemorrhage).(64) When it comes to stroke, high cholesterol definitely increases the risk of the more widespread ischemic stroke,(65) but cholesterol levels that are too low appear to be a factor in the less common hemorrhagic stroke. Fortunately, enough published data exists to confidently recommend that maintaining cholesterol levels between 180 and 200 is the best way of protecting against either type of stroke.(66-68)