What is Cholesterol? 6 Things to Know About Your Numbers
What is cholesterol?
Cholesterol is a waxy, fat-like substance used by each cell in your body. All cells can make their own cholesterol, but most is made in the liver and transported to cells within lipoproteins. An easy analogy is to visualize cholesterol (and triglycerides) as passengers, and lipoproteins as boats.
New data from the Global Burden of Disease estimators confirms that high concentrations of blood cholesterol carried in low density lipoproteins, or LDL-C, is the second most important risk factor for cardiovascular disease globally, after high blood pressure. When LDL-C levels are elevated these lipoproteins and their cholesterol passengers "sail" into artery walls, causing them to become inflamed and to narrow and harden. This process is called atherosclerosis, starts early in life, and can lead to heart attack and stroke as well as vascular dementia. Cholesterol carried in very low density lipoprotein (or VLDL-C) is another potent risk factor for heart attack and common in those with elevated triglycerides. Chronically low HDL-Cholesterol (also known as "good" cholesterol) is also a risk factor.
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.
The dangers 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.
The importance of cholesterol screening
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.
The frequency of cholesterol screening varies based on risk factors and age.
The AHA recommends that all children undergo universal screening for cholesterol levels before puberty, or around the age of nine to eleven. Children with a family history of very high cholesterol are recommended for screening at age two.
Adults over 20 should have their cholesterol checked every four to six years if they don't have other risk factors. However, adults with a family history of heart disease or high cholesterol, or personal history of diabetes, very high cholesterol levels, high blood pressure, or obesity should be screened more frequently.
Know your cholesterol numbers and talk to your provider
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.
Ways to lower your cholesterol
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!
About the Author:
Karen Asprey, MD, and Verity Ramirez, 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.
Dr. Verity Ramirez is a cardiologist with the Lifespan Cardiovascular Institute. Dr. Ramirez’s research interests include infective endocarditis, hypertrophic cardiomyopathy, coronary artery dissection, and behavior modification and cardiovascular disease.