Medicosnext
Dr. Sanjaya Kumar Shrestha,
Professor of Cardiology,
Kathmandu Medical College
Heart attacks and strokes remain the leading cause of death worldwide. For decades, cholesterol has been blamed as the primary culprit — but is that really the case? As a cardiologist who has spent years studying cardiovascular disease, I believe it’s time to challenge one of the biggest misconceptions in modern medicine: that cholesterol is the enemy.
Rethinking Cholesterol: The Misunderstood Molecule
We’ve been conditioned to fear high cholesterol. Medical guidelines define “normal” ranges, and any deviation above those levels is met with alarm. But cholesterol is not inherently harmful. In fact, it plays a vital role in our health. It is crucial for hormone production, vitamin D synthesis, and—most importantly—for maintaining the structural integrity of cell membranes, especially those lining our arteries.
Ironically, it’s not an excess of cholesterol that causes heart disease — but rather, a deficiency of cholesterol in the cell membranes of blood vessel linings that may trigger the process of atherosclerosis.
What Really Causes Heart Attacks and Strokes?
To understand this, imagine your arteries as pipes carrying blood to vital organs. Just like water pipes, these arteries can be damaged over time. When the inner lining (endothelium) of arteries is injured, plaque can build up in the damaged areas — a process known as atherosclerosis. These plaques can narrow arteries, causing chest pain during physical exertion. If a plaque ruptures or erodes, it can trigger a blood clot that completely blocks the artery. This sudden blockage is what causes a heart attack or stroke.
But what causes the initial damage to the inner lining of arteries?
The answer lies in mechanical and biochemical stress. The endothelium, especially the arterial endothelium, endures constant pressure of flowing blood and exposure to harmful compounds, especially advanced glycation end-products (AGEs) formed by excess sugar in the bloodstream. These stresses damage the endothelial cells, which are then repaired by the body’s natural healing process, the inflammatory reaction — similar to how a cut on the skin heals with a scar. In the arteries, however, this “scar” is known as a plaque.
The Role of Cholesterol in Arterial Health
Our body contains around 30 trillion cells, all with delicate membranes composed of double layers of phospholipids regularly interspersed with cholesterol molecules. While phospholipids are fragile and temperature-sensitive, cholesterol provides stability and strength to these membranes.
The endothelium, constantly under attack of mechanical and biochemical stresses, needs a steady supply of cholesterol and phospholipids to repair itself and maintain its function. While most cells produce their own cholesterol and phospholipid, endothelial cells require additional cholesterol and phospholipid from the bloodstream, carried by lipoproteins like LDL (low-density lipoprotein) and HDL (high-density lipoprotein).
Contrary to popular belief, LDL is not inherently harmful. It is simply a transport vehicle, delivering cholesterol to cells that need it. Demonizing LDL has distracted us from the real problem: when cells cannot absorb enough cholesterol, they become vulnerable to damage.
The Real Story Behind High Cholesterol
The notion that high cholesterol causes heart disease can be traced back to mid-19th-century research by German scientist Rudolf Virchow, who observed cholesterol in arterial plaques. But his observations did not prove causation — just correlation.
This misunderstanding was amplified by the Framingham Heart Study in the late 1940s, which showed that high cholesterol levels were associated with increased risk of ischemic heart disease. However, when the data were closely examined, they revealed two overlapping bell curves: many people with “high” cholesterol never had heart attacks, while many with “normal” cholesterol did. The real risk became significant only when cholesterol levels exceeded 300 mg/dL, a level usually seen in a genetic condition called Familial Hypercholesterolemia (FH).
Familial Hypercholesterolemia: A Special Case
People with FH lack enough LDL receptors on their cells. These receptors allow cholesterol to enter cells for membrane repair and maintenance. Without them, cholesterol builds up in the blood but not in the cells — especially in the endothelial cells that need it most.
The result? High blood cholesterol and cholesterol-starved arteries, which are more prone to damage, inflammation, and plaque formation. FH affects roughly 1 in 200 to 1 in 300 people, but is more common in certain populations, such as French Canadians, where it may affect 1 in 80.
It is possible that the Framingham Heart Study may have unintentionally combined data from people with FH and those without — leading to a misleading conclusion about the dangers of cholesterol.
So, Should You Fear Cholesterol?
Only if your cholesterol level is extremely high (around 300 mg/dL) — a range suggestive of familial hypercholesterolemia. For the vast majority of people, moderately elevated cholesterol is not a direct threat.
Instead, we should focus on protecting the endothelium — the true frontline in the fight against heart disease.
Practical Advice: How to Keep Your Arteries Healthy
The key to preventing heart attacks and strokes is minimizing the stress on your arterial walls. Here’s how:
– Lower your blood pressure: Keep salt intake low from an early age.
– Control blood sugar: Avoid sugary foods and processed carbohydrates that increase harmful AGEs.
– Stay physically active: Regular movement helps maintain healthy blood vessels.
– Avoid smoking: Smoking directly damages the endothelium.
– Don’t fear cholesterol — understand it: It’s not the enemy. It’s a vital part of your body’s repair system.
Final Thoughts
Cholesterol has been wrongly accused for far too long. It’s time we updated our understanding of its role in heart disease. Instead of focusing on lowering cholesterol at all costs, we should prioritize supporting arterial health and addressing the real risk factors — high blood pressure, high blood sugar, and inflammation. And remember: healthy arteries, not low cholesterol, are your best defense against heart disease.
If you’re concerned about your cholesterol levels and for related questions or more information, feel free to reach out to me at sanjayakumar70@gmail.com.
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