LDL: What to Know About the "Bad" Cholesterol

A waxy compound found in your body’s cells, cholesterol is manufactured in the liver and present in some foods. There are two types of proteins that carry cholesterol through the bloodstream: high density lipoprotein (HDL) and low density lipoprotein (LDL). HDL is considered “good” cholesterol, as it absorbs cholesterol and brings it back to the liver, whereas LDL is “bad" cholesterol.

What makes LDL so concerning? Why is it bad? High levels can cause plaque to form in your arteries. In turn, this can lead to a range of serious conditions, such as coronary artery disease (CAD) and peripheral artery disease (PAD), among others. These diseases are leading causes of heart attack and stroke.

This being the case, checking LDL levels—as part of a broader assessment of cholesterol—is an essential part of a routine physical. If your levels are high, you’ll need to manage the condition, which can mean everything from adopting lifestyle changes to taking medication. Learning more about cholesterol and LDL helps you understand your health overall.

Why LDL Cholesterol Is Bad

The chief issue when there are excessive levels of LDL is the formation of plaque within the walls of arteries, leading to atherosclerosis. These atherosclerotic plaques can stiffen, narrow, and harden the walls of the arteries, which deliver oxygen-rich blood from the heart to the rest of the body.

Also, the plaques can rupture, which causes different types of blood cells to come rushing to the exposed ruptured plaque, stick to it, and acutely clog the artery. The acute clogging can cause a heart attack or stroke, depending upon which artery is clogged.

Constriction or blockages of blood flow lead to a veritable cascade of serious health conditions. When they occur in coronary arteries (those of the heart), you can develop CAD, which can lead to heart attack.

High LDL is also associated with diseases of other arteries, as in PAD and carotid artery disease. Blockages in carotid arteries from CAD can lead to a stroke, while blockages in peripheral arteries are more likely to cause pain in the arms or legs.

Measuring LDL Cholesterol Levels

Given the severity of what it can lead to, it’s little wonder that screening LDL levels is an important and essential part of health evaluation. This is measured using a blood test called a lipoprotein profile. Here’s a breakdown of how the assessment works:

• Fasting: You may have to fast for 9 to 12 hours before your appointment for an accurate LDL level. This means holding back from eating, having certain beverages, or taking some medications.
• Sampling: The lipoprotein test, like other blood tests, only requires a small sample of blood. It’s usually drawn from a vein in the arm, and all you’ll feel is a pinprick.
• Multiple Measures: The amounts of four lipoproteins are measured: LDL, HDL, triglyceride, and total cholesterol levels. Other lipoproteins such as very low-density lipoprotein (VLDL) may be measured as well.

Recommendations as to how often you should have your cholesterol levels checked vary based on your age and health status. Typically, adults over the age of 20 should be screened once every five years, with the first test administered when children are 9 to 11. Men aged 45 to 65, and women 55 to 65 should be screened every one to two years.

However, more frequent assessment is needed for those who have certain risk-factors for heart disease, including:

• Genetics or family history of heart problems as well as high cholesterol levels.
• Diabetes mellitus patients have elevated LDL and lower HDL levels.
• Age is a risk-factor, with older individuals being at greater risk.
• Being male gendered is associated with a higher chance of developing heart problems.
• Smoking or exposure to cigarette smoke are notorious risk factors.
• Being overweight or obese are also factors that call for more testing.
• Medical history of having high cholesterol—or other factors—can also prompt screening.

Notably, in men over 40, LDL levels will be part of an equation used to determine risk of developing stroke or heart attack within 10 years.

What LDL Levels Mean

When you have your cholesterol checked, you usually receive a consultation to help explain what the measures mean. As mentioned, high LDL levels are a red flag, as are those of triglycerides; when the latter are also higher than normal, it can be a sign that atherosclerosis has already developed.

LDL levels are broken down into five specific categories, defined as optimal and near optimal, often considered healthy ranges, as well as borderline high, high, and very high. The results are expressed as milligrams (mg) per deciliter (dL).

How LDL Impacts Total Cholesterol

Physiologically speaking, LDL represents a majority of your blood cholesterol; however, as noted, HDL and triglycerides are also present in significant amounts. Total cholesterol levels—while not as clinically significant for isolated heart and circulation issues—give a decent glimpse of cardiovascular health.

So how does LDL impact total cholesterol levels? Total cholesterol is a composite score calculated by adding up LDL and HDL levels with 20% of the triglyceride score. Normal levels of this type are less than 170 mg/dL for those under 20, and between 125 and 200 mg/dL for adults. Forty percent of that score is determined by LDL, which is also a significant measure in its own right.

Dangers of High LDL Cholesterol

Elevated LDL levels are associated with a range of medical conditions, some of which are very dangerous. Most notable of these are:

• CAD: Leading to chest pains (angina), shortness of breath, heart palpitations, elevated heart rate, dizziness and nausea, sweating, and muscular weakness. This can lead to heart attack, among other severe and potentially fatal complications.
• Carotid artery disease: The carotid arteries are important arteries on each side of the neck. If atherosclerosis blocks these, stroke can arise.
• PAD: Partial or complete blockage of arteries outside of the heart, especially in the lower limbs, can lead to swelling, muscular weakness, inflammation, and pain, especially when active.
• Heart attack: Occlusion of the coronary arteries leads to muscles in the heart not getting the oxygen they need. This condition, characterized by angina, breathing difficulties, among other symptoms, leads to cell death in this organ and is a medical emergency.
• Stroke: Another common complication of high LDL and its associated conditions is stroke, an attack due to the rapid death of brain cells. As with other issues, this occurs due to clotting in arteries of the brain.
• Cardiac arrest: In very rare cases, high LDL, especially if it leads to CAD, can cause your heart to suddenly stop. This is fatal if not treated immediately.

How To Lower High LDL Cholesterol

If your LDL levels are found to be borderline high, high, or very high, you’ll need to manage the condition and lower them. While some approaches can be challenging to keep up with, they’re usually quite successful. Oftentimes, successfully lowering bad cholesterol will require mixing and matching methods. What’s most important is that you detect any abnormalities as soon as you can and remain proactive in taking them on.

Diet

One of the most influential factors in determining cholesterol and LDL levels is diet. On top of a well-balanced diet, you’ll need to steer clear of food-borne sources of cholesterol, trans fats, and saturated fat. This may mean avoiding:

• Red meat
• Sugary foods
• Many dairy products
• Fast foods

In place of these, a heart-healthy diet should help. This emphasizes:

• Fresh fruits
• Fresh vegetables
• Lean meats (poultry and fish)
• Whole grain foods

Oftentimes, the treatment of high LDL entails counseling about diet, among other lifestyle factors that can help.

Exercise

Regular exercise, along with a good diet, can also help bring LDL levels to an optimal range. Currently, it’s recommended that you aim for a bare minimum of 150 minutes (2.5 hours) of physical activity a week. This can be more extensive fitness work, or it can be as simple as taking a daily—or nearly daily—30 minute walk.

Weight Loss

One of the strongest risk factors for developing high LDL, as well as associated heart diseases or other issues, is being overweight or obese. Losing even 10 pounds can go a long way towards significantly improving your health status. However, it’s also important to be careful and safe; talk to your doctor or a nutritionist about healthy and sustainable ways to shed pounds.

Medications

Several classes of drugs can help take on high LDL levels. These include:

• Statins: This type of medication acts on the liver to reduce the amount of cholesterol it can produce. These popular drugs are very often prescribed in cases of heart attack and stroke. There are many types sold in the United States, including Lipitor (atorvastatin), Lescol (fluvastatin), and Mevacor (lovastatin).   
• Bile acid sequestrants: Sometimes referred to as “resins,” this class of drug cling to the bile acid produced in the liver, rendering it unable to function in digestion. In turn, your liver is stimulated to produce more bile, using up cholesterol. These drugs include Questran (cholestyramine), Colestid (colestipol), and WelChol (colesevelam Hcl).
• Fibrates: This class of drug is more effective in cutting down triglyceride levels and raising HDL, though it can also temper LDL. These include Antara, Tricor, and Fenoglide, which are all different names for fenofibrate.
• Other drugs: Several other drugs may be used to act directly on LDL levels. Among these are PCSK9 inhibitors, which include Praluent (alirocumab), Repatha (evolocumab), and Leqvio (inclisiran); selective cholesterol absorption inhibitors like Zetia (ezemtimibe); ACL inhibitors, such as Nexletol (bempedoic acid), as well as omega 3 fatty acids and niacin.   

Other Lifestyle Changes

In addition to diet, exercise, and medications, there are several other lifestyle changes that can help lower LDL cholesterol levels. These include:

• Quitting smoking: Among the many health benefits of stopping tobacco use are immediate improvements in cholesterol levels.
• Lowering stress: Stress can also cause cardiac issues and impact cholesterol levels. Figuring out ways to manage this healthily—as with yoga or meditation—can be another way to reduce LDL levels.

Lipoprotein apheresis

For those with highly elevated LDL levels that are resistant to management or treatment, as in an inherited condition called familial hypercholesterolemia, a nonsurgical treatment called lipoprotein apheresis may also be used. This involves running blood plasma through a special machine that removes LDL.

This technique is highly efficient in reducing these levels—reducing levels by 70% to 83% in a session. However, the liver is usually able to restore these levels, so treatments may need to occur regularly.  

Summary

Screening blood tests to measure LDL cholesterol levels are important in assessing your long-term risk for cardiovascular disease. If your risk is found to be elevated due to your LDL levels, you will need to work with your health care provider to take the necessary steps to bring that risk down.

FAQs

What is a normal LDL level? 

While healthy ranges of overall cholesterol vary based on how old you are and your sex, the normal, healthy range for LDL is consistent. For men and women over the age of 19, doctors want to see this level below 100 mg/dL.

What causes high LDL cholesterol? 

High LDL is when there are unhealthy elevated levels of this cholesterol in your blood. A range of factors cause these to rise, including:

• Diet: Eating an excess of foods high in saturated fat and cholesterol, as in fatty cuts of meat, dairy products, bacon, cakes, sausages, and others, raises levels.
• Weight status: Being overweight or obese causes increases in LDL levels, making weight management an integral part of managing this condition.
• Physical activity: Those that don't get enough exercise or are too sedentary are at risk of high LDL due to weight gain or excessive weight status.
• Genetics: High LDL can be an inherited condition and runs in families. If you know of relatives with high cholesterol, be aware that you may be at higher risk.
• Medications: A side-effect of some classes of pharmaceutical drugs is high LDL. This can happen with beta-blockers, diuretics, some types of birth control, antivirals, and antiseizure drugs (also known as anticonvulsants), among others.
• Medical conditions: Human immunodeficiency virus (HIV/AIDS), chronic kidney disease, and diabetes are among the conditions that lead to spikes in LDL.

What should I do if my LDL cholesterol is high? 

If your LDL is found to be high, you and your doctor will need to come up with a plan to manage this condition. You'll get instructions about dietary changes you need to make and will be encouraged to adopt a healthier, more active lifestyle; this is typically the first step in taking on high cholesterol.

Make sure your levels are being regularly monitored, and keep track of your progress. If changing lifestyle habits alone isn't enough, you and your doctor can consider pharmaceutical approaches.

How can I lower my LDL cholesterol without medications?

The first step in managing any case of high LDL is through adopting healthy, therapeutic lifestyle changes (TLC). The key to TLC is:

• Adjusting diet: Adopting specific, heart-healthy eating habits, such as the TLC diet, Mediterranean diet, or the Dietary Approaches to Hypertension (DASH) eating plan can dramatically improve LDL levels. These limit intake of trans fats, salt, and cholesterol, while boosting healthy, unsaturated fats.
• Managing weight: If you're overweight or obese, even moderate reductions in weight can help lower LDL. Incorporating healthier lifestyle habits, such as improving diet, sleep quality, and level of physical activity can make a big difference.
• Staying active: Ensuring that you're getting enough physical activity will also help reduce LDL levels. Aiming for a bare minimum of 30 minutes a day of moderate exercise, such as taking daily walks or cycling, can help a great deal.

What medications are used to reduce LDL cholesterol? 

There are several classes of drugs prescribed for high LDL. These include:

• Statins: These drugs inhibit the activity of enzymes in the liver that produce cholesterol, lowering LDL, while raising HDL. The most commonly prescribed types include Lipitor (atorvastatin), Lescol (fluvastatin), and Advicor (lovastatin), among many others.
• Cholesterol absorption inhibitors: This type of drug, most commonly available as Zetia (ezetimibe) and Vytorin (ezetimibe plus simvastatin), prevents the intestines from absorbing cholesterol.
• Bile acid sequestrants: By spurring the intestine to shed more cholesterol, drugs like Colestid (colestipol), Welchol (colesevelam), and Questran (cholestyramine) help lower LDL levels.
• PCSK9 inhibitors: This newer class of cholesterol-lowering drug, available as Repatha (evolucumab), Praluent (alirocumab), and Leqvio (inclisiran), has shown great promise in lowering LDL. These drugs inhibit proprotein convertase subtilisin/kexin 9 (PCSK9), a protein that regulates cholesterol levels.
• Adenosine triphosphate-citrate lyase (ACL) inhibitors: In adults with genetic high cholesterol, or those with heart disease, ACL inhibitors like Nexletol (bempedoic acid) and Nexlizet (bempedoic acid and ezetimibe) may be prescribed. These are combined with statins and lifestyle changes to improve LDL levels.
• Fibrates: Drugs of this type, such as Lopid (gemfibrozil) andfenofibrate (available as Antara, Lofibra, Tricor, and Triglide), primarily moderate triglyceride levels, though they can also lower LDL.

What is a good LDL to HDL ratio? 

In general, the higher your HDL, and the lower LDL, the better off you are. Optimal cholesterol levels are determined by looking at the ratio of HDL cholesterol to total cholesterol. This is calculated by dividing total cholesterol score by your HDL result, so if your total score is 150, and your HDL is at 50, you'd score a 3:1.

Generally speaking, the higher this number, the higher the risk of heart problems. Doctors want to see a ratio below 5:1, with those below 3.5:1 considered ideal. Since lowering LDL causes total cholesterol numbers to drop, it promotes a better cholesterol ratio.

Can LDL cholesterol levels be too low? 

There is no medically-established LDL level that's too low; however, scores of 40 mg/dL or below have been associated with depression, anxiety, and stroke. Very low levels are also a hallmark of familial hypobetalipoproteinemia, a genetic disorder that causes problems with fat absorption and liver health, while leading to vitamin deficiencies.