Understanding the Difference Between Triglycerides and Cholesterol

You may have heard your doctor talk about triglycerides and cholesterol at a past medical visit. But do you know what these are? Or why they matter for heart health?

Romit Bhattacharya, MD, a preventive cardiologist with the Mass General Brigham Heart and Vascular Institute, explains the similarities and differences and what you need to know to stay healthy.

What are cholesterol and triglycerides?

Cholesterol and triglycerides are lipids — forms of fat that circulate in your blood. Understanding what cholesterol and triglycerides are and what they do can help explain their differences. It can also clarify the unique role each plays in your overall health.

Cholesterol is a waxy, fat-like substance found in every cell in your body. It’s a component of hormones and vitamin D and provides structural support to your cells. Bile salts that help digest your food also contain cholesterol. Your liver produces cholesterol from foods like egg yolks, meat, and dairy products.

Triglycerides are also a type of lipid. But unlike cholesterol, your body can’t make triglycerides. So, you must get them from food.

“After a meal — especially one rich in fat or sugar — your body packages that extra energy into triglycerides, which travel through the bloodstream to supply fuel to tissues,” Dr. Bhattacharya explains.

Triglycerides are a vital energy source. The body breaks them into fatty acids and glycerol that muscles and organs can burn for fuel. Unused triglycerides are stored in fat cells and released later when energy is needed.

Your body needs cholesterol and triglycerides to function, but having too much of either lipid on hand can take a toll on your heart, increasing your risk of heart disease and stroke. And both high cholesterol and high triglycerides (hypertriglyceridemia) share many of the same causes.

What causes high cholesterol?

Your body makes all the cholesterol it needs. However, certain behaviors and factors can make it difficult for the body to get rid of it. This causes cholesterol to build up in your arteries. These include:

• Diet: Eating foods high in saturated and trans fats increases cholesterol.
• Physical inactivity: Being sedentary can cause weight gain, leading to high cholesterol (hypercholesterolemia).
• Body composition: People with greater lean muscle mass and lower body fat percentage tend to have lower cholesterol.
• Genetics: You’re more likely to have high cholesterol if a parent does, too.
• Medical conditions: Kidney disease and type 2 diabetes can raise cholesterol.
• Medicines: Some chemotherapy treatments, heart medicines, and steroids can increase cholesterol.
• Age: As we age, changes in hormones, metabolism, and body composition can lead to higher cholesterol levels, even if diet and habits stay the same.
• Smoking: Cigarettes damage your blood vessels, which makes it easier for fatty deposits to collect.

Over time, the buildup of cholesterol leads to a condition known as atherosclerosis. “Atherosclerosis can cause heart attacks when the lipid-rich plaques burst, kind of like how a pimple pops, and create a blood clot in the artery leading to the heart muscle,” says Dr. Bhattacharya.

What causes high triglycerides?

Normally, triglycerides get broken down quickly before they’re shuttled off to the tissues that need them. “But if too many triglycerides are being produced or if the clearance system isn’t working properly, then these particles will linger in the bloodstream,” Dr. Bhattacharya says.

High triglycerides are more likely to develop in people who:

• Are older
• Don’t exercise
• Consume excessive alcohol
• Have HIV, kidney disease, or liver disease
• Regularly overeat
• Smoke
• Take medicines to treat breast cancer, high blood pressure, or HIV

When triglycerides stick around in the bloodstream for too long, fatty components invade the artery walls. And, like cholesterol, they can build up over time. “Persistently high triglycerides don’t just travel harmlessly in the blood — they can set off a chain of events that leads to atherosclerosis,” Dr. Bhattacharya says.

How do I know if my cholesterol and triglycerides are high?

The National Heart, Lung, and Blood Institute (NHLBI) divides triglycerides into the following categories:

• Healthy: Below 150 milligrams per deciliter (mg/dL)
• Borderline high: Between 150 and 199 mg/dL
• High: Between 200 and 499 mg/dL
• Very high: Above 500 mg/dL

Cholesterol is a bit more complex, separated into three numbers:

1. LDL (“bad”) cholesterol: This is the type of cholesterol that builds up in the arteries and creates blockages. Aim to keep this number at or below 100 mg/dL.
2. HDL (“good”) cholesterol: This substance carries cholesterol to the liver for removal, making it beneficial for heart health. You want at least 40 mg/dL (for men) to 50 mg/dL (for women).

Total cholesterol: This is calculated using your LDL, HDL, and triglyceride numbers. Ideally, your total cholesterol will sit around 150 mg/dL; anything above 200 mg/dL is considered high.

How to lower cholesterol and triglycerides to improve heart health

Treatment varies depending on whether you have high cholesterol, high triglycerides, or both. There are many medications, including statins. But the most effective approach is to make heart-healthy habits.

Here’s what you can do:

• Eat a healthy diet.
• Exercise regularly.
• Get enough sleep. Learn tips to sleep better.
• Limit alcohol.
• Manage stress. Learn how stress affects the heart and get tips to keep it under control.
• Quit smoking.

“Cardiovascular disease takes many decades to develop,” Dr. Bhattacharya says. And oftentimes, the first symptom is a heart attack,” he adds. “The good news is that even small improvements in diet, exercise, and metabolic health can make a measurable difference within months.”

Healthy lifestyle habits and regular health checkups can help lower cholesterol and triglycerides before any damage is done.