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What is Cholesterol? 4 Things to Know About Your Numbers
High cholesterol is a major risk factor for heart attack and stroke. February is Heart Month, and the perfect time to review your heart disease risk factors. 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 10 times 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. About one in 500 people have FH, but in some groups, like French-Canadians, prevalence is 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 (in mg/dl) being carried in your blood in LDL, VLDL and HDL particles. For LDL-cholesterol, an optimal number is 100 mg/dl or less. For VLDL-cholesterol, this number is not usually reported. However, dividing your triglyceride number (optimal 150 mg/dl or less) 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 (HDL, or "good" cholesterol) is generally good.
Once you have your numbers ask your primary care provider (PCP) to calculate your risk of atherosclerotic cardiovascular disease (ASCVD). Your PCP will factor in your cholesterol numbers, age, gender, race, and other risk factors, and estimates your risk of a heart attack or stroke in the next 10 years. If your 10-year ASCVD risk is above average, take these steps to reduce your risk:
- 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.
- Get 150 minutes of moderate intensity exercise each week.
- Lose weight if you’re overweight.
- And don’t smoke.
Learn more about steps you can take to reduce your risk of heart disease.
If your 10-year ASCVD risk is greater than 7.5 percent, also discuss the pros and cons of statin therapy with your PCP. Statins are cholesterol-lowering medications that have been shown to be safe and effective for lowering heart attack risk in more than 25 major clinical trials. Once on a statin, aim for at least a 30 percent and preferably a 50 percent reduction in LDL-cholesterol. Your primary care provider can tailor your dosage depending on your age. Drink plenty of water when taking a statin.
Finally, if your LDL-cholesterol is greater than 190 mg/dl and there is no other medical reason, you likely have a genetic disorder. If you are over age 21, and not pregnant or nursing, guidelines recommend that you take a high intensity statin to lower your heart disease risk.
Remember, early detection and treatment are the keys to prevention of heart attacks and strokes!
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 Cardiac Rehabilitation Program.