The common advice often heard from doctors, helpful government agencies,
women's magazines and the back of your cereal box is that cholesterol causes
heart disease. "Artery clogging fats" are the evil to be avoided and that
everyone should monitor their blood lipids, ever vigilant against "bad" LDL. All
of this comes from two outdated, disproven hypotheses: the diet-heart hypothesis
and the lipid hypothesis. Both are both predicated on similar grounds: the fat
in your blood causes plaque and heart disease.
Fortunately science, researchers and many cardiologists have moved on.
Unfortunately most everyone else is still getting their information from the
1970's... Below is a rundown of how I understand the relationship between
cholesterol, LDL and heart disease. The short version: LDL isn't
"bad", eating fat doesn't raise your cholesterol and eating saturated fat is
actually good for you.
Recent large scale studies have shown that for women, the
higher your cholesterol is, the less likely you are to die from all causes
of death, including heart disease. For men, moderately high cholesterol was
also associated with a lower risk of death. Check out
my blog post for more detail.
What is cholesterol, LDL, etc?
I found it difficult to really digest and understand the information
about cholesterol, LDL and HDL until I learned what they really were. So
often the media, blogs, etc will throw around these terms without clearly
defining them. Check out Bio 101: HDL and LDL for
a quick overview.
How is LDL involved with Heart Disease?
- When a cell's membrane reacts with the oxygen in your blood, the
entire cell breaks down. This is oxidation.
- The by-products of oxidized LDL cause inflammation, irritating the
surrounding cells. The immune system responds by cleaning up the mess and
creates a plaque (like a scab) to protect the nearby cells. 1
- Plaque by itself doesn't cause too much harm,
but over time plaque can build up due to continued damage from oxidized LDL
particles. When this happens, the artery will
become less flexible, narrower and the likelihood of the plaque breaking off is
increased. If the plaque breaks off, it can cause a clot. Clots are
the cause of heart attacks and strokes.
- The longer a LDL particle circulates in your blood, the greater
chance that it will be oxidized.
- Small dense particles are not inherently bad but its size can be a clue that the
particle is older and thus more likely to have been oxidized.
- When you have reduced LDL receptors or they aren't functioning
efficiently, LDL isn't taken up by your cells very quickly and "lives
- Some people genetically have fewer LDL receptors. You would know
already if you fell into this category.
- LDL receptors are active when either the cell needs cholesterol or
the body sends signals that food is abundant so the cell should create more sex hormones
bile acid or more sperm, etc and generally be an active cell.
- If you have a metabolic disorder, such as obesity, thyroid
dysfunction, diabetes, etc, your cells may not respond well to these
signals or your body may not be sending them at all. I believe this is
one reason why heart disease is
correlated with metabolic disorders. If your body isn't recycling and
using LDL very often, they have extra time to oxidize and cause damage.
How does diet affect LDL?
- Saturated fats, such as butter or coconut oil, commonly raise both your
LDL and your HDL.
- Diets high in carbohydrates skew your LDL to be mostly small, dense
pattern B LDL. Diets high in saturated fat and low in carbohydrates cause
you to have mostly large, fluffy pattern A LDL.
- Your diet affects the composition of the lipoprotein cell membrane.
The food you eat are the building blocks, so if you eat saturated fat,
the membrane is made of saturated fat. If you eat unsaturated fats, then
the membrane is composed of unsaturated fats.
- Saturated fats are much less vulnerable to oxidation than
unsaturated fats (especially polyunsaturated fats which are the most
fragile). So by eating more saturated fats than polyunsaturated, you
are protecting your LDL from oxidation. Note that you make more than
just LDL out of the fat you eat, so this principle applies to more
than just LDL. Eating saturated fats protects your body from
- Similarly, when you eat antioxidants, your cells can use them
like armor to protect themselves from oxidation. So eating a variety
of whole foods (meats, organs and vegetables) gives your body
additional protection from oxidation.
So my biggest question is this: Since a LCHF (low carb high fat) diet is
associated with mostly pattern A LDL, does that mean that your risk of heart
disease is lessened? It's not entirely clear.
One potential reason that high carbohydrate diets are associate with
pattern B LDL is that it affects LDL receptors, causing LDL to live
longer. Which is not good because lesser LDL receptor activity » longer LDL
lifetime » increased oxidation » increased in heart disease risk.
Another idea is that these diets change the composition of your VLDL to
begin with such that they quickly convert from VLDL directly to pattern B
LDL, but doesn't increase the LDL lifespan. In which case maybe the
difference is irrelevant and even the new more accurate lipid tests like the
NMR and VAP tests (which measure LDL size) don't give you any better
information than you had before, simply looking at your HDL and triglyceride
I don't have an answer though I learn towards the first theory. Here's what I takeaway from all this:
- Eating saturated fats is better for my health and polyunsaturated or
fats (e.g. vegetable, canola, seed and nut oils) should be limited.
- Eating a variety of whole foods, especially organ meats, will increase my
- I want my blood lipids results to look this this:
- High HDL because it is resistant to oxidation.
- Pattern A LDL because is less likely
to have been oxidized.
- Low triglycerides because that is an indicator that I am not
badly insulin resistant.
- LDL in a safe range because when it's extremely
low/high it may be an indicator that something else is wrong.
Most of the information here is my understanding and regurgitation of an
interview with Chris Masterjohn. After listening to the interview, I read a
bit more on his website but most of it came from the first part of his
interview with Chris Kresser, aka The Healthy Skeptic.
High Cholesterol and Heart Disease - Myth or Truth? - Chris Masterjohn
The Central Role of Thyroid Hormone in Governing LDL Receptor Activity and the Risk of Heart Disease - Chris Masterjohn
The Healthy Skeptic Podcast #11 Interview with Chis Masterjohn on Cholesterol and Heart Disease (Part 1)
The Healthy Skeptic Podcast #16 Interview with Chis Masterjohn on Cholesterol and Heart Disease (Part 2)