A reader asks for comments on some specific points:
“I was wondering what are your thoughts concerning these issues from a book, “The Cholesterol Myth?”
My comments in response to Ravnskovs cholesterol myth points are below in blue.
- Cholesterol is not a deadly poison, but a substance vital to the cells of all mammals. There are no such things as good or bad cholesterol, but mental stress, physical activity and change of body weight may influence the level of blood cholesterol. A high cholesterol is not dangerous by itself, but may reflect an unhealthy condition, or it may be totally innocent.
Cholesterol is definitely NOT a deadly poison. It is a substance vital to all the cells of all mammals. It’s a matter of balance and of finding the optimum level of ingestion so that the body gets an overall benefit, not a negative effect. There are different forms of cholesterol and some are disease promoting, like the small LDL which is tiny enough to get underneath the lining of blood vessel walls and cause narrowing of arteries. Some are more helpful, like HDL, the “garbage truck” of the system that goes around to pick up all the excess poorly deposited cholesterol that it can. A sedentary lifestyle, stress, and excess weight can all lead to higher cholesterol levels. MOST data indicate that cholesterol is a serious risk factor for heart attacks. To be dangerous, that doesn’t mean it has to act “by itself.” For instance, the high cholesterol must first form a plaque in the lining of the blood vessel wall. Then a stimulus comes along, some form of inflammation or infection, which makes the cholesterol plaque explode. It is the explosion that is the heart attack. One factor without the other wouldn’t do much.
2 A high blood cholesterol is said to promote atherosclerosis and thus also coronary heart disease. But many studies have shown that people whose blood cholesterol is low become just as atherosclerotic as people whose cholesterol is high.
This statement is pretty simplistic for a few reasons.
- Blood cholesterol levels are affected by what you eat and when you eat it. Put most people on a low-fat diet for 3 weeks and the cholesterol level of their blood test will be low. But if before that 3 weeks someone was eating tons of saturated fat, then they’ve got years of cholesterol buildup stuck beneath the lining of the blood vessel wall. It WILL reverse on a low-fat diet, but it takes time. At a year you can see some regression. At five years you see more.
- There are genetic differences. Some people have more of the small LDL but yet their total cholesterol levels are not so terribly high. Or they process things differently so that low levels can still wreak havoc.
- There are other reasons for heart attacks. High cholesterol is a serious risk factor. It’s not everything.
3 Your body produces three to four times more cholesterol than you eat. The production of cholesterol increases when you eat little cholesterol and decreases when you eat much. This explains why the “prudent” diet cannot lower cholesterol more than on average a few per cent.
Yes, the body produces much, much more cholesterol from the intake of saturated fat than it gets from actually ingesting cholesterol itself. That’s part of why eggs and shellfish aren’t so evil. They may have relatively high levels of cholesterol, but ingested cholesterol is not nearly as important as saturated fat which the body turns into cholesterol. The body is efficient. If you eat a unit of cholesterol, then that’s one less unit the metabolic machinery of the body has to manufacture. That does NOT explain “why the prudent diet cannot lower the cholesterol more than on average a few percent.” In fact, it can. In the Lifestyle Heart Trial, LDL cholesterol dropped 40% without the help of any medication. That’s about as much as is seen with Lipitor, one of the most widely prescribed pharmaceuticals.
“Cholesterol-rich foods that are relatively low in saturated fatty acid content (notably egg yolks and, to a lesser extent, shellfish) have smaller effects on LDL cholesterol levels.” American Heart Association Dietary Guidellines: Revision 2000
“Saturated fat is the principal dietary determinant of LDL cholesterollevels.” American Heart Association Dietary Guidelines: Revision 2000.
4 There is no evidence that too much animal fat and cholesterol in the diet promotes atherosclerosis or heart attacks. For instance, more than twenty studies have shown that people who have had a heart attack havent eaten more fat of any kind than other people, and degree of atherosclerosis at autopsy is unrelated with the diet.
This one is simply not true. A recent meta-analysis of existing data shows that lowering saturated fat in the diet reduces the risk of having a heart attack by 20%.
Another recent large study examining the Atkins Diet found that people who eat animal fat, which is primarily saturated fat, are more likely to die sooner than those eating only vegetable fat, which is un-saturated fat, while on a low-carb diet.
“The major food components that raise LDL cholesterol are saturated fatty acids, trans-unsaturated fatty acids, and, to a lesser extent, cholesterol.” American Heart Association Dietary Guidelines: Revision 2000