Understanding Cholesterol

 Get Your Cholesterol in Check

-  By Knvul Sheikh, a New York Times reporter covering chronic and infectious diseases and other aspects of personal health.

Credit: Molly Cook Escobar (NY Times)

Introduction: High cholesterol, caused mainly by eating high-saturated-fat and high-trans foods, not exercising enough, being overweight, smoking and drinking alcohol, can cause blockage of the arteries, making it more likely to have heart problems or strokes. High cholesterol can also run genetically in some families. To get a risk assessment of cholesterol in your blood you need to take a 12-hour-fasting blood test which reveals levels of HDL, LDL and triglycerides, which combined with other factors, such as your age, blood pressure and health conditions will determine your QRISK score.

Getting your cholesterol tested — and under control — is critical to preventing heart disease and other serious health problems. But figuring out when to test and what to make of the numbers can feel daunting.
How harmful is “bad cholesterol” for your health? Should you worry if your total cholesterol is just on the cusp of being too high? And how much can you lower your levels by changing your diet or exercise habits?

We asked experts what to know about cholesterol tests and management.

What is cholesterol?

Cholesterol is a fatty substance (also called a lipid) that is produced by the liver. It’s essential for making cell membranes, hormones and more. Usually, your liver makes all the cholesterol you need. But some foods, like meat and dairy products, may increase the cholesterol circulating in your blood, which is why you may be asked to fast before a cholesterol test.

Cholesterol gets a bad rap because there’s strong evidence linking higher levels to plaque buildup in the arteries and the hardening of blood vessel walls over time. In medical terms, this is called atherosclerosis. Eventually, the buildup can block blood flow to your heart, causing a heart attack. Pieces of plaque can also rupture and travel to other parts of your body, causing a stroke.

Most people don’t have any symptoms until their arteries are already severely clogged. That’s why doctors look to cholesterol levels to catch and treat cardiovascular problems early, said Dr. John Wilkins, an associate professor of cardiology and epidemiology at Northwestern University Feinberg School of Medicine.

When do you need a cholesterol test?

According to the American Heart Association, all adults 20 or older should get their cholesterol checked every four to six years. You may need more frequent checks for certain risk factors, such as high blood pressure, diabetes or a family history of heart disease.

However, heart disease is becoming increasingly prevalent among younger people. The National Heart, Lung and Blood Institute recommends starting cholesterol testing between the ages of 9 and 11, or as young as 2 years old if there is a strong family history of high cholesterol and heart disease. Your doctor can help you decide when it’s time for a test.

What do cholesterol tests show?

A doctor can check your cholesterol through a blood test called a lipid panel or lipoprotein profile. This measures total cholesterol; low-density lipoprotein, or LDL, cholesterol; high-density lipoprotein, or HDL, cholesterol; and triglycerides, another type of fat that hardens the arteries and mainly comes from food. These are all reported in milligrams per deciliter.

Sometimes the test includes very-low-density lipoprotein, or VLDL, which carries triglycerides to different parts of the body.

For some people, a doctor may also order a test for apolipoprotein B, or ApoB, which is the particle that actually carries the cholesterol in your blood. This is considered a more accurate predictor of heart attack risk, particularly if you have moderate or only slightly elevated LDL numbers, said Dr. Stephen Kopecky, a preventive cardiologist at Mayo Clinic in Rochester, Minn.

A handful of home tests use a blood sample from a finger prick to check cholesterol. If you use one of these tests, you should still discuss your results with a doctor and, when possible, get in-person testing, which is considered more reliable.

What are normal cholesterol levels?

What counts as “normal” depends on several factors. Cholesterol levels generally increase with age. Men tend to have higher levels throughout their lives, while women typically experience an increase during pregnancy or at menopause. Certain genes can also influence how much cholesterol your body makes.

Perhaps the most important number to track is your LDL, which is considered the “bad cholesterol” that can build up on artery walls. For most people, LDL should be below 100 mg/dL — the lower, the better.

People with diabetes, existing plaque buildup or other factors that put them at risk of heart disease may need to keep LDL below 70, said Dr. Douglas Jacoby, medical director of the Penn Medicine Center for Preventive Cardiology and Lipid Management.

High triglyceride levels are also associated with an increased risk of heart disease. Ideally, high triglyceride levels should stay under 150 mg/dL.

HDL, also known as “good cholesterol,” picks up extra cholesterol from your arteries and carries it back to the liver so it can be removed from the body. That is why higher HDL levels are generally considered better. Aim to keep HDL above 40 mg/dL, with above 60 considered optimal.  Studies have shown that heart disease risk among South Asians for a given cholesterol level is much higher (almost double) than in other ethnic groups, primarily due to Low HDL levels. Studies of patients with premature heart disease have shown that low HLD levels are three times more likely a cause than very high LDL levels. For every 10-point increase in HDL, the risk for heart disease is reduced by half!

But when HDL is higher than 80 mg/dL in men or 100 mg/dL in women, it may lose its protective function and instead accelerate atherosclerosis, some studies suggest.

Is there any value in total cholesterol levels?

It can be trickier to assess your heart disease risk when LDL or triglyceride levels fall into a “borderline high” category. In these cases, a doctor may review some additional calculations included in your test report, such as your total cholesterol, which is calculated by adding HDL, LDL and 20 per cent of your triglyceride level.

An even more useful measure may be the non-HDL number, which can indicate how much of the total cholesterol is made up of LDL and other artery-clogging particles. This number doesn’t include triglycerides, so it may more accurately reflect your cholesterol when you’re eating normally, rather than fasting for a blood test.

Doctors can also look at your cholesterol ratio, which is the total cholesterol divided by HDL. The higher the ratio, the greater your risk of heart disease.

What can I do to lower my cholesterol?

Eating more soluble fibre in the form of legumes, whole grains, seeds, fruit and vegetables can help bind cholesterol in the digestive tract and remove it from your body. Some foods, like nuts, avocados and fatty fish, also contain polyunsaturated fats, which lower LDL cholesterol in the blood.

Try to limit foods high in saturated fats, trans fats and cholesterol, such as red meat, butter and cheese, and choose plant proteins like soy and minimally processed foods instead.

Though the effects of these dietary choices on cholesterol vary from person to person, they can still “lower your risk of heart attack or stroke or dying within three months” of making diet changes, Dr. Kopecky said.

Exercising a few days a week, 30 minutes a day or 150 minutes a week, can further decrease your LDL and triglyceride levels while increasing HDL cholesterol, Dr. Kopecky said. And these lifestyle changes can substantially benefit even those who need cholesterol-lowering drugs.

Weight management is important for improving the lipid profile. South Asians are at high risk for abdominal obesity which increases total cholesterol levels and increases the risk for diabetes. An abdominal circumference of 32 inches or greater in women and 36 inches or greater in men is the cutoff for obesity. In addition, the BMI cutoff (body mass index calculated as total body weight in kilograms divided by height in meters squared) for obesity in South Asians is 23 or higher (versus 25 or greater in the general population).

What about cholesterol medication?

A doctor may recommend cholesterol-lowering drugs if you have already had a heart attack or stroke or if an ultrasound or angiogram shows significant blockages in your arteries. A provider may also consider medication if your LDL cholesterol is 190 or higher.

For most other people, doctors consider cholesterol levels in combination with age, family history of heart disease, smoking history and other factors before deciding whether to prescribe a drug, Dr. Wilkins said.

The most commonly prescribed cholesterol drugs are statins, which reduce LDL cholesterol. It may take some trial and error to find the right drug and dose, Dr. Wilkins added, and most people need to stay on statins for life. Stopping the medication can cause your cholesterol levels and risk of developing heart disease to go back up.

“No one has zero risk,” he said. “But there’s a lot you can do to mitigate it.”
. 

References: 

2.

1. Sheikh, K. (2024, January 31). Why cholesterol is important for health and how to lower it. The New York Times. Retrieved February 18, 2024, from https://www.nytimes.com/2024/01/31/well/live/cholesterol-tests-levels-heart-disease.html

2. Cholesterol and South Asians - The balance between good and bad cholesterol is an important contributor to cardiovascular and stroke risk. (2015, July 27). Indian Heart Association. Retrieved February 18, 2024, from https://indianheartassociation.org/cholesterol-and-south-asians

Footnote: 

A version of this article appears in print on Feb. 6, 2024, Section D, Page 7 of the New York edition with the headline: Don’t Be Daunted: Get Cholesterol Levels Checked.