Why Cholesterol Matters



Cholesterol can be confusing — how can something that is necessary for human life, that is present in every cell, be bad for us?

Cholesterol is a soft, waxy, fat-like substance that is found in cells inside the body. It is used in the body’s synthesis of various hormones and bile acids. Because it is in every cell, your liver makes all the cholesterol you need and then circulates it through the blood. It cannot dissolve in blood, and so particles known as lipoproteins help transport it from the liver to the cells via the bloodstream.

Understanding the Basics

There are three types of lipids (fatty substances) in the blood — low-density lipoprotein, high-density lipoprotein and triglycerides.

Low-density lipoprotein cholesterol (LDL-C) — LDL-C sticks to artery walls, contributing to the formation of plaque, a thick, hard deposit that can clog arteries and make them less flexible. LDL-C is often called “bad” cholesterol, and low levels of it are considered good for your heart.

High-density lipoprotein cholesterol (HDL-C) — HDL-C is known as “good” cholesterol because it helps remove LDL-C from your arteries, transporting it to your liver for removal. A higher level of HDL-C is considered good for your heart; low levels of it have been shown to increase the risk of heart disease.

Triglyceride — Triglyceride is the most common type of fat in the body. A high triglyceride level combined with low HDL cholesterol or high LDL cholesterol is associated with atherosclerosis.

Why LDL-C and Triglyceride Levels Matter

The plaque buildup in arteries that LDL-C & triglycerides contribute to is known as atherosclerosis (“hardening of the arteries”). When plaque builds up, it can partly or entirely block the blood flow of an artery in the heart, brain, pelvis, legs, arms or kidneys. This can lead to coronary heart disease, angina (chest pain), carotid artery disease, peripheral artery disease and chronic kidney disease.

Atherosclerosis can also lead to a heart attack or stroke. That’s because a couple of things can happen where plaque occurs:

  • A piece of plaque may break off.
  • A blood clot (thrombus) may form on the uneven surface of plaque buildup.

If either of these travels through the body, ultimately lodging in an artery to the heart, it causes a heart attack. If lodged in an artery to, or in, the brain, a stroke results.

Why HDL-C Levels Matter

While the problem with LDL-C is having too much, the problem with HDL-C is having too little. It’s important to have healthy levels of HDL-C to help keep LDL-C in check.

Why Knowing Your Numbers Matters

In the past, treatment guidelines directed healthcare providers to focus on treating their patients to target goal levels for a total cholesterol number — comprised of the total of HDL-C, LDL-C and one-fifth of the triglyceride level. The ratio of LDL-C to HDL-C was calculated. But the current scientific guidance recommends going about it differently.

“We look at LDL-C and HDL-C independently. This is because a very high LDL-C is a risk factor for CVD [cardiovascular disease], even if HDL-C is high. Using the ratio can “mask” the problem of a high LDL-C,” said Penny Kris-Etherton, Ph.D., R.D., professor in the Department of Nutritional Sciences at Penn State University.

Knowing numbers is still important — in fact, guidelines stress that it’s important to consider several health-related numbers when determining whether cholesterol needs medical attention to reduce risk of atherosclerosis and its many potentially serious consequences. Your specific numbers are still important, but the best treatment considers your specific numbers AND your overall risk assessment and reduction opportunities. The American Heart Association recommends that you be aware of five key numbers: Total cholesterol, HDL (good) cholesterol, blood pressure, fasting blood sugar and body mass index (BMI).

Ideal numbers for most adults are:

Lowering LDL-C: How Diet Matters

Penny Kris-Etherton, Ph., R.D.

It’s less about intake of dietary cholesterol and more about intake of bad fats.

“Dietary cholesterol and cholesterol produced in the body are used for the synthesis of different hormones, such as testosterone, and also bile acids,” Kris-Etherton said. “But dietary cholesterol has a small cholesterol raising effect that is less than saturated fat.”

Saturated fat, which is solid at room temperature, and trans fat (manufactured by adding hydrogen to vegetable oil) tend to raise LDL-C. Your liver produces more cholesterol when you eat a diet high in these two things.

Most saturated fat comes from animal products such as beef, lamb, pork, poultry with skin, butter, cream, cheese and other dairy products made from whole or 2 percent milk. It is also found in solid fats, which are used in baked goods, confectionary products and savory snacks. Plant sources of saturated fat include coconut, coconut oil, palm oil and palm kernel oil (often called tropical oils) and cocoa butter.

Trans fat can be found in many foods — including fried foods like doughnuts, and baked goods including cakes, pie crusts, biscuits, frozen pizza, cookies, crackers and stick margarines and other spreads. Check the Nutrition Facts panel of packaged food, but be aware, products can be listed as “0 grams of trans fats” if they contain 0 grams to less than 0.5 grams of trans fat per serving. Reading the ingredient list can help you spot trans fats by looking for ingredients referred to as “partially hydrogenated oils.”

The American Heart Association recommends that adults who would benefit from lowering LDL-C limit their saturated fat intake to 5 percent to 6 percent of total calories each day. For a person who needs 2,000 calories a day, this is about 11 to 13 grams of saturated fat.

Bottom line, for dietary changes to have an impact on lowering LDL-C, keep a keen eye on your intake of saturated fat and trans fat, they are more likely to increase your levels than dietary cholesterol itself. The American Heart Association recommends emphasizing intake of vegetables, fruits and whole grains; low-fat dairy products, poultry, fish, legumes, nontropical vegetable oils and nuts. Limit intake of sweets, sugar-sweetened beverages and red meats.

Cholesterol in the Genes

Some people have high cholesterol in their genes. This genetic defect is called familial hypercholesterolemia (FH). FH is a defect in the body’s ability to recycle LDL-C in the liver. Because of that, the LDL-C levels remain above 190 mg/ dL in adults with FH. Over time those levels are toxic to blood vessels, and atherosclerotic plaques develop, which causes fatty deposits in the arteries that trigger an inflammatory response, which leads to a very elevated risk of coronary heart disease, much higher than the average population and much earlier in life. Half of men with untreated FH will have a heart attack before age 50. Thirty percent of untreated women will have one before 60.

For more on FH, see our previous article, Cholesterol in the Family.

Lowering LDL-C: Diet May Not Be Enough

For some people, lowering saturated fat intake may not lower LDL-C levels enough, and a healthcare provider will recommend cholesterol-lowering drugs. Various medications can lower blood cholesterol levels. The most common cholesterol-lowering drugs are called statins. Statins are recommended for most patients because they are the only cholesterol-lowering drug class that has been directly associated with reduced risk for heart attack and stroke.

Statins disrupt production of cholesterol by blocking an enzyme inside the liver cells. This means less cholesterol is being released into the bloodstream. Your doctor may consider other medications as well, especially if you have serious side effects or your body doesn’t respond to statin therapy alone enough to meet the health goals you’ve established together.

Some statins also reduce the inflammatory process in the vessel wall. This helps stop plaque buildup in arteries, keeping them stronger and less likely to rupture.

Raising HDL-C: Do the Right Things

So far, efforts to increase HDL-C levels with drugs haven’t proven to reduce cardiac risk, and no HDL-C enhancing drugs have been approved by the FDA. There are some dietary and lifestyle changes that can help, but Kris-Etherton cautions not to expect big changes.

  • Get physically active. Some studies suggest that physical activity can raise HDL. The American Heart Association recommends three to four 40-minute sessions of moderate- to vigorous-intensity aerobic activity per week for adults trying to lower their LDL cholesterol or blood pressure.
  • Eat better fats. The monounsaturated and polyunsaturated fats described above can raise HDL-C levels.
  • Cut out trans fats. Not only do they increase LDL-C, they decrease HDL-C.
  • Lose weight. Being overweight increases LDL-C and reduces HDL-C. Losing even a few pounds will increase your HDL-C and lower your LDL-C and blood pressure.
  • Stop smoking. Smoking decreases HDL-C levels, and stopping smoking may increase them.

Even if making these lifestyle changes results in only a small change in HDL-C levels, keep at them — they’re all good for your overall heart-health.

For more, visit our Common Misconceptions About Cholesterol page on Heart.org.

Cholesterol Misconceptions

Using margarine instead of butter will lower my cholesterol

Both margarine and butter are high in saturated fat, which increases LDL-C, so use both in moderation. Limiting food high in saturated fat and trans fat may help reduce bad cholesterol. Most vegetable oils and soft or liquid margarines have less saturated and trans fat than solid spreads, and are preferable to the stick forms of margarine for a heart-healthy diet. When selecting a margarine, choose one that has 0 grams trans fat on the Nutrition Facts label.

Thin people don't have to worry about high cholesterol.

Any body type can have high cholesterol. True, overweight people are more likely to have high cholesterol, but everybody, including thin people, should have their cholesterol checked regularly. People who do not gain weight easily are often less aware of how much saturated and trans fat they eat. Nobody can “eat anything they want” and stay heart-healthy.

Since the food label on my favorite food says "low cholesterol," I can be sure it is sure it is "heart-healthy."

Many “low-cholesterol” foods contain high levels of saturated fat and/or trans fat — both of which contribute to raising LDL-C. Some foods that claim to be “low-fat” may have a higher fat content than expected. Look for the amount of saturated fat, trans fat, and total calories in a serving of the product. Also check the size of one serving. Often it’s smaller than you think. The first item listed in the ingredients list is the one used most in the product, so choose products where fats and oils appear near the end of the list.

Remember that one change — like switching from butter to soft margarine — is a good step, but may not be enough to reduce your cholesterol to healthy levels. Other diet and lifestyle changes or medication may be needed, as your doctor recommends.

This information is provided as a resource to our readers. The tips, products or resources listed or linked to have not been reviewed or endorsed by the American Heart Association.


See also: 

My Number Was 350, the story of cholesterol patient Lisa Ranson.


 


 

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