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Writter:
DM, Cardiology,
Consultant interventional cardiologist,
Palmerston North Hospital,
Health New Zealand
Beyond the Myth: The Truth About Cholesterol. It’s true that cholesterol is essential to our body, playing a key role in the normal functioning of cells and membranes.
Cholesterol Production:
About 85% of cholesterol is produced internally by the body, while only 15% comes from external sources, such as our diet.
Dietary Cholesterol:
All dietary cholesterol comes from animal-based foods like dairy and meat—plant-based foods contain absolutely no cholesterol. Yes, Zilch! Nada!
However, the devil is in the details when it comes to the type of cholesterol and how much of it accumulates in our bloodstream.
We all know that there are two primary types of cholesterol carried by lipoproteins:
LDL often referred to as “bad” cholesterol, can cause plaque buildup leading to atherosclerosis & raises the risk of heart attacks and strokes.
HDL or “good” cholesterol, helps clear excess cholesterol from the bloodstream, transporting it to the liver for processing and elimination.
Lifestyle Factors and Cholesterol:
Even though the lion’s share of cholesterol is produced by the body, lifestyle factors—such as diet, exercise, and genetics—play a crucial role in determining how much LDL and HDL circulate in the blood.
When LDL levels are too high, or HDL levels too low, cholesterol becomes a major player in cardiovascular diseases, like coronary artery disease.
LDL vs. HDL: The Cholesterol Balance
In a nutshell, it’s not cholesterol itself that’s the enemy but rather the imbalance between LDL and HDL—particularly high LDL and low HDL—that puts heart health on the line.
The Science Behind LDL and Cardiovascular Risk:
The evidence for LDL as a key cardiovascular risk factor is rock solid, proven time and again through extensive clinical trials. It’s also clear-cut that lowering LDL levels reduces the risk of cardiovascular events and mortality—there’s no disputing the science on that front. A prime example is familial hypercholesterolemia (FCH), a genetic condition that causes dangerously high LDL levels from birth, often leading to premature CAD and we know that reducing LDL levels in these patients reduces the risk of CAD.
Why do people have Heart Attack with normal cholesterol:
One common question is: If high cholesterol levels lead to heart attacks, why do some people still develop heart attacks even with normal total cholesterol and LDL levels?
Heart attacks can occur even in people with normal LDL or total cholesterol levels for several reasons. While high cholesterol, particularly high LDL, is a significant risk factor for heart disease, it’s not the only factor at play.
Here are some reasons why heart attacks may still occur despite normal cholesterol levels:
1. Inflammation and Other Risk Factors:
– Inflammation in the blood vessels can increase the risk of heart attacks. Conditions like diabetes, high blood pressure, and obesity can damage the blood vessels even if cholesterol levels are normal.
– Smoking, sedentary lifestyle, and chronic stress also contribute to heart disease by promoting inflammation and narrowing of arteries.
2. Genetics and Family History:
– Some individuals have a genetic predisposition to heart disease, independent of their cholesterol levels. For example, people with a family history of early heart attacks might still be at risk due to inherited factors affecting their arteries or clotting mechanisms.
3. Small Dense LDL Particles:
– Even with normal LDL levels, the *type* of LDL matters. Small, dense LDL particles are more likely to penetrate artery walls and form plaques than larger LDL particles, increasing the risk of atherosclerosis and heart attacks.
4. Lipoprotein(a) Levels
– Elevated Lipoprotein(a) is an independent risk factor for cardiovascular disease. Lp(a) can promote clot formation and plaque buildup in arteries, leading to heart attacks, even in those with normal LDL or total cholesterol.
5. Triglycerides and Low HDL
– High triglyceride levels and low levels of HDL (the “good” cholesterol) can increase cardiovascular risk. Even with normal LDL, an imbalance between these factors can contribute to plaque buildup in the arteries.
6. Coronary Artery Spasm
– In some cases, a coronary artery spasm can lead to a heart attack. This occurs when the arteries that supply blood to the heart tighten or spasm, restricting blood flow. This can happen even in people with no significant plaque buildup or with normal cholesterol levels.
7. Plaque Instability and Rupture
– Some people may have unstable plaques in their arteries. Even though the arteries might not be significantly narrowed, these plaques can rupture, causing a sudden blockage that leads to a heart attack. This can happen even in people with normal cholesterol levels.
8. Diabetes and Insulin Resistance
– Diabetes and insulin resistance significantly increase the risk of heart attacks, even in individuals with normal cholesterol. High blood sugar levels damage blood vessels and promote plaque formation, leading to cardiovascular complications.
In summary, while cholesterol levels are important, they are only one piece of the puzzle when it comes to heart health. Other factors like inflammation, genetics, and metabolic conditions can contribute to heart attacks, even when cholesterol levels appear normal.
Conclusion:
Beyond the Myth: The Truth About Cholesterol. While cholesterol is a necessary component of our bodies, it’s the delicate balance between LDL and HDL that determines our cardiovascular risk. High LDL levels, often referred to as “bad” cholesterol, can lead to plaque buildup in arteries and increase the risk of heart disease.
Conversely, high HDL levels, or “good” cholesterol, can help remove excess cholesterol from the bloodstream. Lifestyle factors, such as diet and exercise, play a significant role in managing cholesterol levels.
By understanding the importance of this balance and taking proactive steps to maintain healthy cholesterol levels, we can significantly reduce our risk of cardiovascular problems and enjoy a healthier life.