What is Cholesterol? 4 Things to Know About Your Numbers
High cholesterol is a major risk factor for heart attack and stroke. Here is what you should know about blood cholesterol and how to improve your numbers, and your heart health.
1 – What is cholesterol?
Cholesterol is a fatty substance used by each cell in your body. It is so vital to health that every cell can make its own supply if needed. However, most cells prefer to get cholesterol from something called “lipoproteins.” These little particles are made by the liver and intestine and sent out into the bloodstream. It’s best to think of lipoprotein particles as “ships” that carry cholesterol and triglyceride passengers throughout the body. A protein on the surface functions like the captain, deciding which “ports of call” in the body to stop at on the way to the final destination. The lipoprotein ships set sail with many more triglyceride than cholesterol passengers. Those from the liver are called VLDL (or very low-density lipoproteins). At the major ports of call (muscle and fat stores) almost all the triglyceride passengers get off the ship. In people with “normal” cholesterol, docks on the liver surface quickly remove most of the returning cholesterol-rich particles, called LDL (or low-density lipoproteins), and only 25 percent sail off to other body cells.
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2 – What causes high cholesterol?
High cholesterol is usually caused by either of two conditions. There are either too many VLDL particles made by the liver, which creates too many cholesterol-rich LDL particles. Or the liver is unable to remove LDL particles from the blood as quickly as it should. Diet plays a key role. Eating too many refined carbohydrates and added sugars drives the liver to overproduce VLDL particles. Likewise, a diet high in animal fats like butter, cheese, cream, fatty cuts of beef and pork, or tropical oils, like coconut oil, can make it harder for the liver to clear LDL particles from blood. High cholesterol levels can also be hereditary. For example, familial hypercholesterolemia, (FH), is caused by a genetic defect that impairs the liver’s ability to remove LDL particles from the blood, causing high levels that begin before birth. Older estimates showed that about 1 in 500 in the general population have FH, but new data show the prevalence is actually around 1 in 250, and in some groups, like French-Canadians, prevalence is even higher.
3 – The risks of high cholesterol
Studies from around the world have now shown that people with a higher level of blood cholesterol have a higher risk of heart attack. The risk is about four to five times greater for those with the highest levels compared to the lowest of LDL-cholesterol. Research has shown that increased numbers of cholesterol-rich LDL particles in the bloodstream leads to their entry into artery walls. Once trapped there, LDL particles trigger inflammation, creating the “perfect storm” for the build up of the artery-clogging plaques that cause heart attack and stroke. The one good thing is that the timeline is long – giving us a chance to reverse the process.
4 – Know your numbers and talk to your provider
The first step to knowing if you are at risk from high cholesterol is to get screened. A standard blood test will show the concentration of cholesterol being carried in LDL particles in your blood—an optimal number is 100 mg/dl or less. Dividing your triglyceride number by five will give you the amount of cholesterol being carried in VLDL—an optimal number is 30 mg/dl or less. A higher amount of cholesterol carried in high-density lipoprotein (or HDL) is generally good. Your total cholesterol will be the sum of these three numbers.
[Note: the following has been updated based on 2018 guidelines]
Once you have your numbers, enter them into the ASCVD Risk Estimator (a free app available for download), which will ask you to enter your age, gender, race, blood pressure, and whether you have diabetes, high blood pressure or smoke. This is key -- it is no longer good enough for you or your primary care provider to just look at your numbers and estimate your risk -- the risk estimator step is needed. If you are age 40 or older, the app will calculate your risk of ASCVD over the next 10 years. If you are age 20-39, it will estimate only your lifetime risk of ASCVD. After this step, follow the latest Cholesterol Treatment Guideline for what to do next, which may include taking a statin based on your risk estimate and personal risk factors.
Note, if your LDL-cholesterol is greater than 190 mg/dl and there is no other medical reason, you likely have a genetic disorder. You should not use the risk calculator to estimate your risk. If you are over age 21, and not pregnant or nursing, the guideline recommends that you take a high intensity statin to lower your risk of a future heart attack or stroke.
If you are recommended to take a statin, remember these cholesterol-lowering medications have been shown to be safe and effective for lowering heart attack risk in more than 25 major clinical trials over almost 30 years. Once on a statin, aim for at least a 30 percent and preferably a 50 percent reduction in LDL-cholesterol because each one percent reduction in LDL-cholesterol translates to a one percent reduction in risk. Your PCP can tailor your dosage depending on your age. Drink plenty of water when taking a statin.
No matter what your risk, a healthy diet and lifestyle are the first step towards prevention:
- Eat a diet high in whole grains, fruits, vegetables, healthy proteins like beans, legumes, lentils, fish, and nuts, and use only healthy fats, like olive oil.
- Avoid processed foods high in added sodium or sugars.
- Get at least 150 minutes of moderate intensity exercise each week.
- Lose weight if you’re overweight.
- Don’t smoke or vape.
Learn more about steps you can take to reduce your risk of heart disease.
Remember, early detection and treatment are the keys to prevention of heart attacks and strokes!
[Updated December 2018]
About the Author:
Karen Aspry, MD
Dr. Karen Aspry is a cardiologist and lipid specialist. She is director of the Lifespan Cardiovascular Institute Lipid and Prevention Program, with locations in Providence, East Providence and East Greenwich, and Associate Director of The Miriam Hospital Center for Cardiac Fitness, and Dean Ornish Intensive Cardiac Rehabilitation Program.
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