The common thing many of us hear today is that LDL cholesterol causes heart disease but is this really accurate. Would it surprise you if I said I do not think this is accurate? Does LDL cause heart disease according to the literature or according to medical dogma? There is a study that was recently published in the journal Expert Review of Clinical Pharmacology which seems to add to a growing body of evidence that high LDL cholesterol level do not cause heart disease.
Cholesterol is an essential molecule that is found in the cellular walls of all animals, including the human variety. Cholesterol has an important role to play in the way our bodies function because the cellular wall is an important structure in a cell. Our cells can create it’s own cholesterol but we also absorb cholesterol when we eat animal based foods. The more cholesterol our bodies absorb, the less our cells make. Cholesterol is also a precursor molecule, important for the creation of vitamin D, cortisol, aldosterone, progesterone, estrogen, and testosterone. So cholesterol is important for our cells to function and for our bodies to produce it’s own vitamin d and all steroid hormones.
Everyone knows what it looks like when you have oil and water mixed together, they don’t combine but stay separated right? In our blood stream cholesterol needs a molecule to transport it because it is not soluble in our blood just as oil and water. Lipoproteins carry cholesterol in the blood stream, we have all heard of two of these as HDL (high density lipoprotein) and LDL (low density lipoprotein.) Generally speaking, LDL transports cholesterol from where it is stored or created to the cells that need it. HDL transports cholesterol to the Liver, typically for elimination or excretion. These lipoproteins are neither bad nor good because we need them both but we call LDL “bad cholesterol” anyway, cholesterol itself is not “bad”either, it is essential for our bodies to function.
Atherosclerosis is caused due to a buildup of plaque inside the walls of our arteries and that plaque is primarily made up of LDL molecules. So the traditional thought is that LDL is the cause of the plaque buildup seen in atherosclerosis, so if we reduce the amount of LDL that should reduce the plaque buildup and reduce the instance of atherosclerosis and disease associated with it. The problem is studies just like the one that started this whole post is that high-LDL appears to not be related to heart disease, a condition known to be connected to atherosclerosis. The authors of this study took a comprehensive look at the literature on cholesterol and heart disease and found that there is no evidence that shows high LDL levels cause heart disease. They point out that some papers have found an association but an association is not the same as a causation. The authors note people with low levels of LDL become just as atherosclerotic as people with high levels and their risk of suffering from heart disease is the same or higher as people with high levels of LDL. From their paper, I took away the notion that these authors are concerned that there is a different cause of heart disease out there that is being missed because the only focus for years has been on cholesterol levels. In their conclusions the authors state;
“The cholesterol hypothesis has been kept alive for decades by reviewers who have used misleading statistics, excluded the results from unsuccessful trials and ignored numerous contradictory observations.”
The common thought is that high LDL levels is the cause of heart disease but as we get more people on statins, which are great at lowering cholesterol, the rate of heart disease is not falling proportional to lowering LDL levels. LDL obviously plays a role in atherosclerosis as it is found in the plaques that form in our arteries but I think there is a cause there that many are still missing. Since this blog post is going a bit long, I’ll just say stay tuned. I will post what I think is to blame in another post to come.