Dietary Fat and Heart Disease

Information about which foods are healthy and which may lead to disease can be confusing, especially when it comes to dietary fat. Is fat good for you or not?

The answer depends on what type of fat you eat. Debbie Krivitsky, RD, LDN, a Mass General Brigham dietitian in the Corrigan Minehan Heart Center Cardiovascular Disease Prevention Center, discusses how dietary fat affects heart health. She also explains why saturated fat increases heart disease risk and which fats promote health.

What is dietary fat?

Fat is a nutrient found in many foods. “Fats provide a concentrated source of calories, so being mindful of the amount of fat that you include will be helpful when managing weight. This is important because being overweight is a risk factor for all chronic disease,” says Krivitsky. “And we know from research that a high-fat diet increases your risk for heart problems and cancer.”

But not all fats are unhealthy, and we do need some fat in our diet. Fat is necessary for thermal insulation and protection. It’s also critical for absorbing fat-soluble vitamins such as vitamins A, D, E, and K, which are all essential nutrients.

“Fat makes food taste better, and it helps you feel full longer,” says Krivitsky. “You want to include the right type of fat for a positive effect on cholesterol, and make sure you don’t get too much fat.”

How does fat affect the heart?

When you eat fats, they get broken down by your liver and combined with a protein molecule. This fat-protein packet is called a lipoprotein. Lipoproteins can enter your bloodstream, where your body can utilize them.

One type of lipoprotein, called low-density lipoprotein (LDL), is also known as “bad” cholesterol. LDL gets deposited in the linings of your arteries and can lead to the buildup of plaque. Plaque buildup can restrict the flow of blood to your heart or your brain, leading to a heart attack or stroke. High cholesterol, especially high LDL, is a predictor of future heart events such as heart attacks.

“But where there’s a villain, there’s also a hero, and that’s HDL or high-density lipoprotein,” says Krivitsky. “HDL is ‘good’ cholesterol. It removes LDL from your blood vessels so your body can get rid of it.” While HDL has a protective role for your heart, its role in predicting a heart event such as a heart attack is unclear.

Saturated fat and heart disease

To limit your risk of heart disease, be mindful of your intake of saturated fats, which can lead to high LDL cholesterol. High LDL raises the risk of heart disease and heart attacks, as it contributes to blockages in your arteries.

Saturated fats generally come from animals and are solid at room temperature. Coconut and palm oils are the only saturated fats from plants.

Foods highest in saturated fat include:

• Beef
• Coconut oil and palm oil
• Dairy products
• Ghee (clarified butter)
• Lamb
• Pork
• Processed meats of any kind

Over time, a diet high in saturated fat raises your risk of heart problems. However, the effects of saturated fat on your blood vessels are also immediate. “Right after you digest a meal high in saturated fat, your blood vessel walls stiffen, and your heart has to work harder to pump blood,” says Krivitsky.

Krivitsky recommends limiting saturated fat as much as possible. Here are some tips to keep your saturated fat intake low:

• Choose low-fat or fat-free dairy. When buying cheese, milk, yogurt, and other milk products, look for the words “fat-free,” “low-fat,” or “skim” on the label.
• Limit your intake of red meat (beef, pork, or lamb) to no more than once a week. If you do include red meat, look for cuts with “round” or “loin” in the name because they are leaner and lower in saturated fat. If you eat ground beef, choose 93% lean.

Should you avoid foods that contain cholesterol?

If high LDL cholesterol raises your risk for heart disease and cardiac events, is it OK to eat foods containing cholesterol? “This is often one of the first questions people ask me about dietary fat,” says Krivitsky. Foods that contain cholesterol include:

• Cheese
• Egg yolks
• Red meat
• Shellfish

High cholesterol is one of the primary risk factors for heart disease. However, for most people, cholesterol that comes from food doesn’t significantly raise blood cholesterol levels. “Some people have a genetic predisposition that causes dietary cholesterol to raise blood cholesterol,” says Krivitsky. If you know you have a genetic risk or family history of high cholesterol, you should be mindful of high-cholesterol foods in your diet.

If you don’t have a genetic concern, you’re unlikely to consume enough cholesterol to impact your blood levels. Including up to four whole eggs a week or eating shellfish, for example, shouldn’t affect your cholesterol.

Choose heart-healthy fats: Unsaturated fats and omega-3s

Fat is an important part of your diet, so include fats that are heart healthy. Some polyunsaturated and monounsaturated fats actually help lower LDL and triglycerides in your body. Triglycerides are a type of fat that contributes to plaque in your arteries. Having high triglycerides is a risk factor for heart disease, heart attack, and other cardiac events.