Often referred to as ‘bad’ cholesterol, LDL (low-density lipoprotein) particles are actually made of a combination of fat and protein and can carry cholesterol and other fats through the blood. When it’s carrying cholesterol, it can be known as LDL-cholesterol (LDL-C). Another type of lipoprotein that can carry cholesterol is HDL (high-density lipoprotein), which is sometimes known as ‘good’ cholesterol. So, what gives LDL such a bad rep compared to HDL? If both seemingly perform similar tasks, why aren’t they both detrimental to people’s health?
When comparing the function of the two lipoproteins, HDL picks up cholesterol and carries it to the liver to be flushed from the body.1 Whereas LDL particles carry cholesterol and other fats around the body, but can interact with and enter the artery wall, triggering the process of plaque development.2 Therefore, high amounts of LDL-C can lead to a buildup of plaque in the blood vessels. In turn, this buildup narrows the inside of the blood vessels or can rupture and cause a clot, blocking blood flow to and from the heart or other organs.
When cardiologists are worried about their patient’s high cholesterol levels, it’s likely due to the link between high LDL-C and heart disease. But should people really be worried about their LDL-C levels in terms of their cardiovascular health? How about HDL-C? Let’s take a deeper look.
Does LDL-Cholesterol Cause Heart Disease?
There is so much misinformation and confusion around LDL-cholesterol that it’s impossible for most people to come to conclusions about its role in heart disease. The two arguments I hear for LDL-C not being a concern are that those with lower LDL-C tend to have worse health outcomes and the fact that a large number of heart attacks happen in people with “normal” LDL-C levels.
The first point is sometimes true. In older populations, we find that those with lower LDL-cholesterol levels can have higher mortality rates.3 The issue is that these studies are not designed to determine if lower LDL-C is the cause, they only identify an association. It turns out that as people age and/or become more ill, the lower their LDL-C can drop.3,4 There are some diseases, such as cancer, that may lower LDL-C levels, and the sicker people get, the less they may eat, also leading to lower LDL-cholesterol. So, their LDL-C levels are low because they’re sick, not the other way around. In fact, individuals who have had genetically low LDL-cholesterol their entire lives have a lower risk of mortality.5,6
On the second point, again it’s true that a “normal” LDL-cholesterol range doesn’t necessarily protect against heart disease. If we look at people with normal LDL-C levels, without other cardiovascular risk factors, we find that the higher the LDL-C level while remaining within the “normal” range, the more atherosclerosis (plaque in the arteries) is present (Figure 1).7 In fact, if you drop LDL-C levels down to 50-70mg/dl (1.3-1.8mmol/L), atherosclerosis is virtually non-existent!8 Therefore, it may be the level that is ideal for humans, meaning that our “normal” range is too high, and a diet group that consistently maintains average LDL-C levels near or below 70mg/dl are vegans.9
The controversy around cholesterol is prevalent in the blogosphere, but there is consensus in most medical circles. You’d be hard pressed to find many cardiologists who don’t think elevated LDL-C leads to heart disease and the European Atherosclerosis Society Consensus Panel has determined that LDL causes atherosclerosis after reviewing the bounties of research on the topic!10 The controversy of the two arguments defending LDL-cholesterol is largely based on misinterpreted data.
Does HDL-Cholesterol Protect Against Heart Disease?
We’ve covered LDL-C, now it’s time to discuss what the deal is with HDL-cholesterol. High HDL-C levels were once thought to be protective against cardiovascular disease (CVD), but that may now be an outdated idea.11 The reason it was believed to be protective is because those with higher levels tend to have lower rates of heart disease, however, this could be a result of HDL-C being a marker for a healthier diet and lifestyle in the general population.
We now know that those with genetically higher levels are not typically protected against heart disease, and drugs that increase HDL-C similarly do not offer protection.12,13 On the other hand, LDL-cholesterol can cause heart disease, as mentioned above, since those with genetically higher levels are at increased risk, and medications or dietary therapies that lower LDL-C protect against CVD.14
When adopting a plant-based diet, HDL-C and LDL-C levels can both decrease, which is a good thing with respect to LDL-C, but some individuals can become concerned with lower HDL-cholesterol levels.15 However, diet and lifestyle changes can also influence the types of HDL particles we have, with plant-based dietary patterns improving cholesterol clearance, and lower saturated fat (typically found in animals) and higher polyunsaturated fat consumption possibly leading to more potent anti-inflammatory properties in HDL particles, which I’ve even heard being referred to as “Super HDL!”16,17 So, it’s the function of the HDL that matters, not necessarily the amount in terms of cardiovascular health.
What’s the Verdict with Cholesterol Levels?
In conclusion, studies have shown that increased levels of LDL-cholesterol in the blood stream put people at greater risk for developing heart disease. Ultimately, HDL-C levels don’t seem to be much of a concern, and far more attention should be placed on lowering LDL-C to protect against cardiovascular disease.
For those wanting to find out how to lower LDL-cholesterol levels, I can provide specific strategies to do so. Click here to book an appointment today.
Matthew Nagra is a Naturopathic Doctor and is a passionate advocate for evidence-based nutrition as medicine. I have a particular passion for plant-based/vegan nutrition, physical medicine, and chronic disease. With additional training in nutrition, I hold a Plant-Based Nutrition Certification from Cornell University and the T. Colin Campbell Center for Nutrition Studies where I’ve authored multiple articles on the subject.