By Daniel Credeur, PhD
September marks National Cholesterol Education Month, making it the perfect opportunity to revisit one of the most misunderstood topics in health care. For decades, cholesterol has been portrayed as something inherently “bad”—a substance to eliminate from our diets and lower at all costs. Yet the truth is far more fascinating.
Without cholesterol, life simply would not exist. Every cell in your body depends on cholesterol to maintain its structure and function. It serves as the building block for hormones such as estrogen and testosterone, helps produce vitamin D when your skin is exposed to sunlight and enables your liver to manufacture bile acids that digest dietary fats.
In fact, your body is so dependent on cholesterol that your liver produces roughly 70-80% of what you need each day. The real question, then, isn’t whether cholesterol is good or bad. It’s whether cholesterol is ending up where it belongs, or where it doesn’t.
Cholesterol’s Journey Through the Bloodstream
Because cholesterol is a fat-like molecule, it cannot travel freely through the watery environment of our bloodstream. Instead, it is packaged into tiny transport particles called lipoproteins, which shuttle cholesterol and other fats throughout the body.
The two most familiar are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL is often labeled the “bad cholesterol” because it delivers cholesterol from the liver to tissues throughout the body. HDL is commonly referred to as the “good cholesterol” because it helps transport excess cholesterol back to the liver for recycling and removal.
While these labels are convenient, they oversimplify a much more complex system. LDL is not inherently harmful—it performs an essential biological function. Problems arise only when too many LDL particles circulate in the bloodstream, particularly when blood vessels have become damaged by years of unhealthy lifestyle habits or underlying medical conditions.
The Story Begins Inside Your Arteries
Heart disease doesn’t begin because cholesterol suddenly “clogs” an artery. It begins with the health of a remarkable tissue called the vascular endothelium.
The endothelium is an incredibly thin layer of cells lining every blood vessel in your body. Although only one cell thick, it functions as one of the body’s most important organs. A healthy endothelium regulates blood flow, controls blood pressure, prevents unwanted clot formation, reduces inflammation, and communicates continuously with the surrounding blood vessels.
One of its most important jobs is producing nitric oxide, a small signaling molecule that tells arteries to relax. When nitric oxide is abundant, blood vessels remain flexible, blood pressure stays lower, circulation improves and the vessel wall resists inflammation. Unfortunately, the endothelium is highly sensitive to our daily habits.
Smoking, uncontrolled diabetes, high blood pressure, prolonged physical inactivity, chronic inflammation and diets consistently high in saturated fats and highly processed foods can gradually impair endothelial function. As nitric oxide production declines, arteries become less able to relax, inflammation increases and the normally smooth vessel lining becomes more susceptible to injury.
Only then do excess LDL particles begin slipping beneath the arterial wall. There, they can become trapped and chemically modified through oxidation. The immune system recognizes these altered particles as abnormal and sends white blood cells called macrophages to remove them. Over time, these cells accumulate cholesterol and transform into what scientists call foam cells, creating the earliest stages of atherosclerotic plaque. This process unfolds silently over decades.
Most people never experience symptoms until blood flow becomes severely restricted, or a plaque suddenly ruptures, triggering a heart attack or stroke.
Movement: Nature’s Medicine for Your Blood Vessels
The encouraging news is that our blood vessels possess an incredible ability to recover. Every time you take a brisk walk, ride a bicycle, swim or participate in structured exercise, something remarkable happens inside your arteries. As blood flow increases, it gently brushes against the endothelial lining, creating a mechanical force known as shear stress.
Although that term may sound harmful, this type of shear stress is actually one of the most powerful signals for vascular health. It stimulates endothelial cells to activate an enzyme called endothelial nitric oxide synthase (eNOS), increasing nitric oxide production and restoring healthy blood vessel function.
The result? Your arteries become more flexible. Blood pressure decreases. Inflammation is reduced. Blood flow improves.
Sitting Less Matters More Than You Think
Many people assume that cardiovascular health depends entirely on going to the gym. Fortunately, that’s not true. Research over the past decade has revealed that prolonged sitting carries its own cardiovascular risks, even among people who exercise regularly.
When we remain seated for hours at a time, blood flow through the legs slows considerably. Reduced movement decreases the beneficial shear stress that normally stimulates nitric oxide production, allowing blood vessel function to gradually decline throughout the day.
The solution is remarkably simple. Stand up every 30-60 minutes. Take a five-minute walk. Walk while talking on the phone. Use the stairs. Park farther away. Small bouts of movement repeated throughout the day help restore circulation and provide your arteries with the mechanical signals they need to remain healthy.
Cardiovascular disease develops gradually over decades, but so does cardiovascular health. The encouraging reality is that it’s never too early, or too late, to begin investing in healthier arteries.
Your heart will thank you for years to come!
Daniel Credeur is Arthrex Director of Research and Career Readiness in the Department of Health Sciences at Florida Gulf Coast University’s Marieb College of Health & Human Services.
References:
2026 ACC/AHA/AACVPR Guideline on the Management of Dyslipidemia. PMID: 41824590
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