A year ago one of my patients began experiencing chest pain when he walked up hills. Subsequent evaluation revealed that atherosclerotic plaque (95% narrowing of a major coronary artery ) was severely reducing the blood flow to his heart muscle and was the cause of his chest pain. When this blockage was opened up with a stent he no longer had the pain.
Along with other medications (aspirin and plavix to keep his stent open) I had him start atorvastatin, the generic version of Lipitor, a powerful statin drug that has been shown to prevent progression of atherosclerotic plaque and thereby reduce subsequent heart attacks, strokes and death in patients like him
I saw him in the office the other day in follow up and he was feeling great . He asked me “Doc I read your post yesterday.s Since you say that cholesterol in the diet doesn’t matter anymore, does that mean I don’t have to take my cholesterol drug anymore.?”
His question gets at the heart of the “diet-heart hypothesis”. The concept that dietary modification, with reduction of cholesterol and fat consumption can reduce coronary heart disease.
The science supporting this hypothesis has never been strong but the concept was foisted on the American public and was widely believed. It was accepted I would say because it has a beautiful simplicity which can be summarized as follows:
“If you eat cholesterol and fat it will enter your blood stream and raise cholesterol levels. This excess cholesterol will then deposit in your arteries, creating fatty plaque , clogging them and leading to a heart attack.”
This concept was really easy to grasp and simplified the public health recommendations.
However, cholesterol blood levels are determined more by cholesterol synthesized in the liver and predicting how dietary modifications will effect these levels is not easy.
Since the public has had the diet-heart hypothesis fed to them for decades and given its beautiful simplicity it is hard to reverse this dogma. My patient’s question reflects a natural concern that if science/doctors got this crucial question so wrong, is everything we know about cholesterol treatment and heart disease wrong?
In other words, are doctors promoting a great cholesterol hoax?
Evidence Strongly Supports Statins in Secondary Prevention
For my patient the science supporting taking a cholesterol-lowering statin drug is very solid. There are multiple excellent studies showing that in patients with established coronary artery disease taking a statin drug substantially reduces their risk of heart attack and dying.
These studies are the kind that provide the most robust proof: randomized, prospective and blinded.
When cardiologists rate the strength of evidence for a certain treatment (as done for lifestyle intervention here) we use a system that categorizes the evidence as Level A, B, or C quality.
LeveleA quality (or strong) evidence consists of multiple,large, well-done, randomized trials such as exist for statins in patients with coronary heart disease.
Level B Evidence comes from a single randomized trial or nonrandomized studies.
Level C evidence is the weakest and comes from “consensus opinion of experts, case studies or standard of care.”
When treatment recommendations are based on Level C evidence they are often reversed as more solid data is obtained. Level A recommendations almost always hold up over time.
The level of evidence supporting restricting dietary cholesterol and fat to reduce heart attacks and strokes has always been at or below Level C and now it is clear that it is insufficient and should be taken out of guideline recommendations.
Evidence Strongly Supports Atherogenic Cholesterol is Related to Coronary Heart Disease
There are other lines of evidence that strongly support the concept that LDL cholesterol (bad cholesterol) or an atherogenic form of LDL cholesterol is strongly related to the development of atherosclerosis. If you are born with really high levels you are at very high risk for coronary heart disease, conversely if you are born with mutations that cause extremely low levels you are highly unlikely to get coronary heart disease.
Thus, the cholesterol hypothesis as it relates to heart disease is very much till intact although the diet-heart hypothesis is not.
Conflating the Diet-Heart Hypothesis and the Cholesterol Hypothesis
There is an abundance of misinformation on the internet that tries to conflate these two concepts. Sites with titles like “The Great Cholesterol Lie” , “The” Cholesterol Hoax”, The Cholesterol Scam” abound .
These sites proclaim that cholesterol is a vital component of cell membranes (it is) and that any attempt by diet or drugs to lower levels will result in severe side effects with no benefit
Doctors, according to these types of sites, in collusion with Big Pharma, have inflated the benefits of statin drugs and overlooked the side effects in the name of profit. Often, a “natural” alternative to statins is promoted. In all cases a book is promoted.
The Great Cholesterol Truths
It’s unfortunate that nutritional guidelines have promoted restriction of cholesterol and fat for so long. These guidelines (like most of nutritional science) were based on flawed observational studies. They should not have been made public policy without more consensus from the scientific community. The good news is that ultimately the truth prevails when enough good scientific studies are done.
It is right to question the flimsy foundation of nutritional recommendations on diet and heart disease but the evidence for statin benefits in patients with established coronary heart disease is rock solid.
Hopefully, the less long-winded explanation I provided my patient in the office will persuade him to keep on taking his atorvastatin pills while simultaneously allowing him to eat eggs, shrimp and full fat dairy without guilt.