What Cholesterol Myth? (part 3)

There’s some people out there, smart ones even, who don’t believe that elevated cholesterol levels are dangerous for your health. One reader recently read The Cholesterol Myth by U. Ravnskov, MD, PhD and wrote to ask my opinion on his anti-cholesterol rhetoric. Is the whole cholesterol thing a scam, a phony issue, a myth?

The mainstream story goes like this:  Animal products and some tropical oils have high levels of saturated fat. Eating a lot of saturated fat increases blood cholesterol levels. Having elevated blood cholesterol increases the chance of dying from a heart attack.

But, well, does it? Does eating saturated fat in the form of meat and whole milk and cheese and eggs and all that other good stuff really lead to heart attacks? Ravnskov’s point is that there is surprisingly little support from good randomized and controlled clinical trials to prove it.

But since Ravnskov stepped down from his soapbox there’s been some new evidence supporting the role of dietary intake of saturated fat (and that means cholesterol as the body sees it) in the development of heart disease. A Harvard study reviewed the literature to date (as of June, 2009) and pooled the existing research to look for an overall effect of replacing saturated fat with poly-unsaturated fat in the form of vegetable and fish oils.

They found that people who replaced saturated fat in their diets with poly-unsaturated fat had a 19% reduced risk of heart disease troubles like heart attacks. For each 5% energy increase of poly-unsaturated fat in the diet substituting for saturated fat, there was a 10% reduction in risk.  It was “dose dependent” so a little reduction of saturated fat helped a little and a big reduction helped a lot. The longer people stuck to the diet change, the greater the benefit that was seen.

The risk of heart disease was reduced by 24% for each 1 mmol/l reduction in total cholesterol. This finding is consistent with results of observational studies of total cholesterol levels and the risk of heart disease.

The Harvard review provides proof from randomized, controlled clinical trials – the gold standard for medical evidence that reducing saturated fat in the diet (and thus cholesterol) and replacing it with poly-unsaturated fat reduces heart attacks. It’s not a myth.

And nobody’s talking drugs here. This is about diet. It’s about what you put into your body.

But there’s one caveat. Because the trials included in this study looked only at replacing saturated with poly-unsaturated fat, it’s not possible from this evidence alone to distinguish between the benefits of reducing saturated fat and the benefits of increasing poly-unsaturated fat. It’s likely they work in concert.

Other studies looking at replacing saturated fat with carbohydrates weren’t so supportive. This may be because of the choice of carb. If participants were eating more refined grains and sugar, then the inflammatory condition inspired by their choices may have counterbalanced any beneficial effect of lowering saturated fat. We know that fructose without fiber (Dr. Lustig’s poison without its antidote) increases triglycerides and the small, dense (ie dangerous) form of LDL. That small form of LDL is what climbs up under the lining of blood vessel walls and forms atherosclerotic plaques of cholesterol that eventually rupture causing a heart attack.

What Cholesterol Myth? (part 2)

The only effective way to lower cholesterol is with drugs, but neither heart mortality or total mortality have been improved with drugs the effect of which is cholesterol-lowering only. On the contrary, these drugs are dangerous to your health and may shorten your life.

Whoa! What kind of nonsense is this? “The only effective way to lower cholesterol is with drugs.” That’s total hogwash. It’s about the diet, baby. What you put into your temple affects what happens inside that temple.

Many people I know just don’t care to eat right. They think they can eat whatever they want and then take a pill to fix it. I see it all the time, even in my own family. I watch my relatives eat fried pork chops, cheeseburgers, and french fries and then go fill their prescriptions for a statin. Poor strategy. ALL drugs have side effects.

But some people have a genetic variation which requires an additional boost from medicine on top of a strict diet. They have to weigh the risk of dying from a heart attack, the leading cause of death in the United States, to the risks of taking a drug which can have harmful side effects. This is an independent, personalized decision.

When it comes to improving mortality, there’s plenty of controversy about using a drug for primary prevention. That means that just because your blood level of cholesterol is high, if you don’t already have heart disease, then you’re probably not getting enough benefit for the risk. The data isn’t really there. But if you have already had a heart attack, then a cholesterol lowering drug may significantly reduce the chances you’ll have another one – or that a second one is fatal. Those drugs work partly by reducing cholesterol, but there is also an indication that they stabilize the cholesterol plaques, preventing that second factor which works in concert, like inflammation or infection, from exploding it.

See a related post of mine here about the potential for harm from cholesterol medications.

 

6  The modern cholesterol-lowering drugs, the statins, do prevent cardiovascular disease, but this is due to other mechanisms than cholesterol-lowering. Unfortunately, they also stimulate cancer in rodents, disturb the functions of the muscles, the heart and the brain and pregnant women taking statins may give birth to children with malformations more severe than those seen after thalidomide.

Um… why can’t it be both? They lower cholesterol and they work by other mechanisms such as stabilizing plaques.

While I’m far, far away from believing that statins should be added to the water supply, there are a few people whose risk-to-benefit ratio makes them useful tools in a total plan that should primarily include diet, exercise, good sleep, stress reduction and weight loss. The trick is to do every freakin’ thing you can to lower your cholesterol to safer levels, and take a drug as a very, very, very last resort. If possible, use it as a bridge for the absolute shortest time possible. They’re not candy. Theyre not a free pass that lets you eat whatever unhealthy food you want. They can be dangerous. It’s not something to take, or to prescribe, lightly.

 

7  Many of these facts have been presented in scientific journals and books for decades but are rarely told to the public by the proponents of the diet-heart idea.

I’m not sure what this means. Science is a long and difficult PROCESS. There are good studies and bad ones, or rather different studies with different kinds of bias and flaws. For almost everything, you can find a study that shows exactly the opposite of what another study shows. The trick is to gather as much information as you can, as much evidence as possible, and then interpret the whole big picture. And the conclusions drawn may very well change over time as data trickles in. That’s good. It means we’re learning. We can’t just snap our fingers and know everything about the human body in an instant. If we could, that would be really awesome.

8  The reason why laymen, doctors and most scientists have been misled is because opposing and disagreeing results are systematically ignored or misquoted in the scientific press.

Um, what I said above.

References:

Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med. 2010 Mar 23;7(3):e1000252.

Fung TT, et al “Low-carbohydrate diets and all-cause and cause-specific mortality” Ann Intern Med 2010; 153: 289-298.

American Heart Association Dietary Guidelines: Revision 2000

http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3full.pdf

Cholesterol Myth Points (part 1)

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.

  1.  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.

  1. 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.
  2. 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.
  3. 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