In this article I will discuss the basics of ‘cholesterol’ (lipoproteins) and cardiovascular diseases. What the relationship is between LDL cholesterol and cardiovascular disease and how diet can influence this. This article is part 2 of a two-part series, the first part covering the role of the molecule cholesterol and lipoproteins in the body and is recommended reading before continuing with this article.
The information in this article comes mainly from this interview by Rhonda Patrick, PhD, with Dr. Ronald Krauss, MD. Dr. Krauss discusses his experience with research into cholesterol, lipoproteins, nutrition and cardiovascular disease. This is a conversation between professional and very in-depth as such. Here, I have summarized the essential message into figures and a brief description (as brief as I could manage 😉 ).
Traits of atherogenic dyslipidemia
To get straight to the point: high LDL cholesterol is not the cause of cardiovascular disease! This issue is far more complex! Dr. Krauss lists the following traits as predictive of cardiovascular issues, so-called atherogenic dyslipidemia:
- High levels of free triglycerides in the blood.
- Low levels of HDL cholesterol.
- High level of small dense LDL particles.
Be aware: these traits are not necessarily the cause of cardiovascular disease, but are commonly found in patients. They are predictive, not causal. In addition, these traits must be present simultaneously.
What is sdLDL
In the previous post I mentioned that lipoproteins are roughly categorized in main categories, but that subcategories can also be made. Most of the time, those subcategories aren’t relevant to understanding the general process, but in this case some LDL subcategories are needed to clarify the process.
Dr. Krauss makes a clear distinction between small dense LDL (sdLDL) and large buoyant LDL (lbLDL). This figure summarizes the main differences.
A) lbLDL and sdLDL differ in size and stickiness to the artery lining. sdLDL is much stickier and smaller than lbLDL. As a result, sdLDL is more likely to get trapped inside the artery wall when the lining is damaged and gaps open up.
B) The liver has special receptors to catch and recycle LDL particles from the blood. lbLDL particles fit much better onto these receptors and are easily cleared. sdLDL particles don’t fit quite as well on the receptor, causing a looser grip on the particle. As a result, sdLDL particles tend to circulate longer than lbLDL particles.
The danger of sdLDL with atherosclerosis
There are several properties of lipoproteins in general and sdLDL in particular that may contribute to atherosclerosis.
- Lipoproteins scavange for (catch) bacterial toxins in the blood. The liver then catches the lipoproteins to remove the bacterial toxins from the body. All lipoproteins have this property, not just LDL.
- LDL particles can contain damaged fats depending on what type of fat is consumed. Polyunsaturated fats are more prone to damage than saturated fats. Damaged fats can trigger an inflammatory response.
- Inflammation is critical in the development of atherosclerosis. Inflammation is damaging to the arterial wall, especially when the cause is not removed and the irritation persists.
- Patients with cardiovascular diseases have higher sdLDL particle levels than healthy controls.
These properties, together with the characteristics of sdLDL particles, provide a more probable theory for the cause of atherosclerosis than simply naming high LDL cholesterol in general as the cause.
sdLDL particles can cause cardiovascular disease because they
- contain damaged fats and bind toxins (which are both inflammatory).
- remain in the blood for longer
- get stuck inside the artery wall very easily.
Nutrition and cardiovascular disease
I expect you’ll agree that it is important to lower sdLDL cholesterol as much as possible to prevent cardiovascular disease. Dr. Krauss speaks about the relationship between nutrition and lipoproteins.
- Eating saturated fats increases lbLDL particles, but not sdLDL. The consequence is likely a higher total LDL cholesterol, but we already discussed that this is not a problem by itself. Saturated fat also increases HDL, which is possibly protective.
- Unsaturated fats from vegetable oils lower LDL but also HDL.
- A high-carbohydrate diet lowers LDL and lbLDL, but increases sdLDL. This effect is especially clear when a large portion of carbohydrates come from sugars, especially fructose.
You may have noticed that the so-called ‘heart-healthy’ diet (low saturated fats, vegetable oils, carbohydrate-rich) most increases sdLDL! In my opinion it is not surprising that more and more people suffer from cardiovascular issues since the introduction of this ‘heart-healthy’ diet. Additionally, many chronic illnesses that plague the developed world (diabetes type II, obesity, Alzheimer’s, cancer) are related to each other through the same heart-destroying diet!
Statins and cardiovascular disease
Statins are drugs prescribed to people with an increased risk of having a heart attack. Statins increase the liver’s ability to take up LDL through the LDL receptor. sdLDL is taken up at a lower rate than lbLDL, but the increased uptake is sufficient to significantly lower the risk of a heart attack.
Statins are very effective at lowering LDL, but they are not without side effects. Dr. Krauss emphasizes the importance of careful selection of at-risk populations. For the right group of patients, statins can be lifesaving. For healthy people or those with lower risk, the statins can cause unjustifiable side effects. Elevated LDL cholesterol by itself is not enough to warrant statin use; other risk factors (we covered them earlier) must also be present.
Dr. Krauss expects that adopting a different diet to reduce sdLDL will have benefits, but mentions that there haven’t been any major studies to substantiate this yet. These are very expensive studies and there are no large stakeholders willing to invest in it. It’s up to the doctor and patient to consider whether dietary changes are potentially beneficial.
- Elevated total LDL cholesterol is not a risk factor for cardiovascular disease.
- Atherogenic dyslipidemia is predictive of heart disease and has these three traits:
- High free triglycerides
- Low HDL cholesterol
- High sdLDL cholesterol
- LDL cholesterol can be subdivided into several categories, including sdLDL and lbLDL.
- A high-sugar diet increases risk factors for cardiovascular disease, while a high-saturated-fat diet lowers these risk factors.
These is of course much more to discuss regarding cardiovascular disease and research is still ongoing. e will have to continue in a future article. For now you have a brief overview of the topics discussed in the interview with Dr. Krauss, as best as I was able to understand and portrait them. I hope this offers a new perspective and clarity on this important but complex topic.