We have become so accustomed to thinking of cholesterol as dangerous, that most people are not aware that cholesterol is essential to life.
To identify just a few benefits of cholesterol:
- Cholesterol makes your cell walls flexible—improving cellular function, especially important for your brain.
- It provides the building blocks for producing hormones, such as testosterone, and nutrients, such as vitamin D.
- It helps cover your nerve cells with a myelin sheath— think of this sheath as the rubber that coats electrical wires to prevent short circuits
- It plays a key role in digesting fats, as it is converted into bile acids that your gallbladder secretes.
There are many forms of cholesterol. Indeed, some forms of cholesterol contribute to arterial plaque growth, while others act like a garbage truck cleaning the arterial walls.
The fact is, not all cholesterol is created equal. So, in truth, it doesn’t make sense to combine the bad and good forms together as “total cholesterol” to calculate your risk for heart disease.
To clarify how different types of cholesterol impact your risk for heart disease, first I will focus on the common forms of cholesterol. Second and likely more important, I will share how the size of cholesterol plays a critical role in your risk for heart disease.
TYPES OF CHOLESTEROL
There are three general types in your body, which blood test results will usually report:
- LDL Cholesterol
- HDL Cholesterol
LDL (Low-Density Lipoprotein) is a bubble of fat and protein that, with a healthy diet, carries nutrients from your intestinal tract to your cells, acting like a delivery truck.
However, if you fill your LDL with damaged fats, it can transform from a nutrient-carrying bubble to an inflamed bubble that forms dangerous plaque along the lining of your arteries.
A normal LDL level is less than 100 mg/dL (milligrams per deciliter) of blood. The average LDL level for people in the United States is around 130 mg/dL; a high LDL level is 160 mg/dL, and an LDL over 190 mg/dL is very high and can be dangerous.
Most cholesterol-lowering drugs are specifically designed to lower LDL cholesterol.
Triglycerides are the most common type of fat in your body. They exist in fat deposits, such as around your waist, and they also float through your bloodstream freely and within LDL particles. The higher your blood triglyceride levels, the greater your risk for plaque buildup.
When your blood sugar is elevated, you typically have high triglyceride levels, as your liver converts sugar into triglycerides.
A normal triglyceride level would be less than 150 mg/dL, while a more optimal level would be 90 mg/dL or less.
HDL ( High-Density Lipoprotein) or “healthy cholesterol,” as I like to think of it, is the trash collector that cruises your blood vessels, picking up all the “bad LDL” and triglyceride garbage in your bloodstream as it cleans your arteries.
The minimal goal for men is an HDL over 40 mg/dL blood, and for women, over 50 mg/dL. Any scores above 55 mg/dL for men and above 65 mg/dL for women are great!
Instead of just LDL and HDL numbers, many medical providers prefer to look at your ratio of total cholesterol (TC) to HDL, basically a comparison of total garbage to garbage trucks. This ratio gives you an estimate as to whether your streets (arteries) are open enough for traffic to pass through.
A normal TC/HDL ratio is less than 3.5, and 3 or lower is excellent. However, the average in the United States is 4.5. If your ratio is more than 5, you are probably growing arterial plaque quickly. For example, if you have a total cholesterol level of 240 mg/dL and an HDL level of 40 mg/dL, your ratio is 6.0, and over time you may be in danger of a cardiovascular event. In my published study identifying cardiovascular biomarkers that predict arterial plaque scores, the TC/HDL ratio was the only cholesterol marker that was predictive— total and LDL cholesterol didn’t help predict plaque growth.
As you’ll see from my discussion below of abnormal cholesterol, these numbers do not tell the full story.
A relatively good total cholesterol score of 180 mg/dL in the presence of other abnormal factors can be much more dangerous than a cholesterol level of 240 mg/dL with otherwise normal cholesterol features. Obviously, a person with a cholesterol level of 300 mg/dL should not ignore these test results.
Is Cholesterol the Most Important Risk Factor for Heart Disease?
From all the cholesterol drug commercials you may see, one would think that cholesterol is the biggest risk factor, but it is not. Abnormal blood sugar levels and blood pressure control are more important than cholesterol in predicting heart disease.
High cholesterol levels versus normal levels increase your risk for a heart attack by about 20%, significant, but less than most people think.
In contrast, when people have high TMAO (tri-methyl amino oxide) levels in their blood, something caused by abnormal bacteria in the gut, that increases the risk for heart disease by 62%. Not many people would have predicted that the gut microbiome appears to be a bigger risk factor for heart disease than your cholesterol level.
THE SIZE OF CHOLESTEROL PARTICLES MATTERS
Surprisingly, some people with very high cholesterol do not develop heart disease. And Many people who have a heart attack have a cholesterol level of less than 180 mg/dL.
So how do we know if our cholesterol profiles are protective or dangerous? Beyond your LDL, triglyceride, and HDL levels, another factor is critical. The issue is the size of your cholesterol particles.
LDL and HDL cholesterol are bubbles of protein and fat that float through your bloodstream. We call these bubbles of cholesterol particles. A variety of research studies show that the size of your LDL and HDL particles is a much stronger predictor for heart disease than your total cholesterol and LDL levels.
LDL cholesterol can be small and dense or big and fluffy. The latter is packed with nutrients and carries fat-soluble vitamins and antioxidants to your cells. The smaller LDL bubbles are the ones to worry about, because they easily become inflamed and cause much more plaque to grow within the lining of your arteries.
Lack of physical activity and a diet high in sugar and refined carbohydrates (carbs) and low in healthy fats will shrink what would normally be a large, fluffy LDL particle into a small, highly inflamed LDL particle. This small LDL particle grows much more plaque. Big, buoyant, fluffy LDL does not.
There is also a super small form of LDL, called lipoprotein a, which is very inflammatory. Its level is determined mostly by genetics, and drugs and lifestyle changes have little impact on it. If lipoprotein levels are high, there is a greater risk for heart disease, especially for those who make poor dietary choices. Yet, research from my clinic suggests that if you follow an optimal lifestyle, you can minimize most of the risk from lipoprotein a.
HDL cholesterol comes in mainly two sizes. HDL2 is big and is effective in hauling away the garbage in the arteries. HDL3, smaller HDL, does not and is unhelpful. Like small LDL, small HDL is formed when you are inactive, eat too much sugar and refined carbs, and do not eat enough healthy fats.
Stay tuned for my next blog on how to improve your cholesterol profiles and the risks and benefits of cholesterol therapy!
For more details on preventing and reversing heart disease, please read the latest edition of my book, The 30-Day Heart Tune-Up.
I wish you the best of health!
Steven Masley, MD, FACN, FAHA, CNS
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