What Causes High LDL or “Bad” Cholesterol? - Verywell Health

Checking cholesterol levels is an important aspect of health care as these can tell you a great deal about your health status. However, there are several types of cholesterol: high density-lipoprotein (HDL) or "good" cholesterol, low density-lipoprotein (LDL), which is often considered "bad" cholesterol, as well as a third type, triglycerides.

Why are higher LDL levels considered unhealthy and dangerous? LDL contributes to the build-up of a waxy, fat-like substance in the arteries. In turn, this can lead to atherosclerosis (a hardening of the arteries), which can lead to coronary artery disease (CAD), heart attack, and stroke among other serious health problems. 

Many factors can cause LDL levels to climb. These include genetic factors (a family history of high LDL), being obese or overweight, lack of physical exercise, diet, and medications you're taking. It's important to understand these causes, as it can help you prevent and manage cholesterol problems.

Verywell / Brianna Gilmartin

What Is High LDL?

Cholesterol itself is a necessary substance in the body. It's manufactured in your liver and it can be present in certain foods, especially meats, eggs, and dairy. LDL is a lipoprotein—a substance that conveys cholesterol to cells, aiding in maintaining cell structure, and serving as a precursor for substances vital to human function. Everyone has some amount of this lipoprotein, but problems arise when these are elevated.

When there is an excess of LDL, plaques build up in the arteries, causing atherosclerosis and reducing blood flow. When your heart's arteries are affected, insufficient oxygen levels damage cardiac muscles and cause CAD, angina (chest pain), and even heart attack. Further, arteries in other parts of the body can also be affected, leading to peripheral artery disease (PAD) and stroke.

Measuring LDL

Given its association with these conditions, it's critical that LDL is measured. How is this done? Basically, this involves a blood test called a lipid profile, which measures HDL and triglyceride levels alongside LDL, while also calculating a total cholesterol score. Particular attention is paid to LDL levels, though all are important.

The lipid profile is a blood test, requiring only a small sample usually drawn from an artery or vein in the arm. You may have to fast for 9 to 12 hours before your appointment, avoiding certain beverages and all food, for an accurate LDL level.

Healthy LDL

So what constitutes a healthy LDL level? This is measured in terms of milligrams (mg) (of LDL) per deciliter (dL) of blood. Your results are fit into four categories: optimal, near optimal, borderline high, and high/very high, with these ranges varying based on age. Here's a quick breakdown:

• Optimal: If you are two to 19 years old, doctors want to see a figure of less than 110 mg/dL. In older adults, doctors want to see less than 100 mg/dL. Notably, if you have CAD, PAD, or other heart problems, this figure needs to be lower than 70 mg/dL.
• Near optimal: For adults above 20 years old, 100 mg/dL to 129 mg/dL qualifies as close to optimal, and usually not a significant concern.
• Borderline: For children and young adults up to 19, scores of 110 mg/dL to 129 mg/dL are considered borderline, meaning that they are verging on dangerous territory. For older people, this range is 130 mg/dL to 159 mg/dL.
• High/very high: Those younger than 20 with scores of 130 mg/dL are considered to have high LDL levels. In adults older than 20, 160 mg/dL to 189 mg/dL is considered "high," and scores above 190 mg/dL are "very high." High levels, of course, are an area of concern.   

Lifestyle

If your LDL levels are high or borderline, your doctor will`tell you about what you can do to lower your numbers. Among the most significant means of taking on this condition are making meaningful lifestyle changes.

Diet

What you eat can have a big impact on your LDL levels. A chief driver of these levels is saturated fat, which, according to the American Heart Association, should constitute only about 5% to 6% of your daily calories. Typically then, you'll need to avoid foods high in this fat, including:

• Lard and cream
• Beef and beef fat
• Lamb and pork
• Skin-on chicken
• Butter and full-fat dairy, including full-fat cheese
• Palm oils

So what sorts of foods can help manage LDL levels? Here's a breakdown:

• Lean proteins: Instead of fattier meats, choose leaner sources of protein, such as fish, chicken (with the skin off), as well as nuts and beans. Fat free or low fat milk are also encouraged.
• Low-fat foods: Foods like fresh vegetables and fruits, whole grain breads, fat-free or low fat yogurts and cheeses, all have low levels of unhealthy saturated and trans fats.
• No added-sugar: Watch out for foods that have added sugars. You may even find many fast or frozen foods—even when savory—add sugar or corn syrup, so be mindful of food labels.  
• Fiber: High fiber foods are another essential component of an LDL-lowering diet. This means leafy vegetables, oatmeal, beans, and apples, among other foods.
• Unsaturated fats: Unsaturated fats are more easily processed by the body, and, in contrast to saturated or trans fats, they can help lower LDL levels, while raising HDL (the good kind of cholesterol). Avocados, nuts, and olive oil are among the foods high in unsaturated fats.     

Weight

Another major risk factor for high LDL is excessive weight. Being overweight or clinically obese limits your body's ability to remove this type of cholesterol from the bloodstream and is directly related to higher levels.

How are these weight statuses defined? The standard measure is the body mass index (BMI), which compares your height and weight to estimate your level of body fat. Whereas scores below 25 are considered normal or underweight, you're overweight if your score is 25 to 29.9, and defined as obese when it's 30 or more.

While there are limitations to BMI as a measure of health, higher scores should be managed. Research has shown that even modest reductions in weight—say 5% to 10% of the starting figure—lowers LDL and reduces other cardiovascular risk factors.

Lack of Physical Activity

Certainly related to the above, insufficient physical activity can also drive LDL higher. The good news, however, is that even modest increases in the amount of exercise you get can help a great deal. Ideally, doctors may want you getting up to 90 minutes a day of physical activity; however, even 30 to 45 minutes regularly can be helpful.

At bare minimum, the surgeon general recommends that adults get 2.5 hours of moderate exercise every week. This can include:

• Biking
• Brisk walking
• Jogging
• Swimming   

Smoking and Alcohol

Among the myriad of negative health effects of smoking tobacco is atherosclerosis, elevated LDL, and lower HDL levels. Quitting this habit, or not starting, goes a long way in managing cholesterol, while also reducing the risk of heart disease and cancers. Talk to your doctor about ways to help you stop.

Second-hand smoke—when you inhale tobacco accidentally from other smokers—is also dangerous and linked with many of the same health problems. If you're a smoker, smoke outside and away from nonsmokers; if you're not a smoker, it's fine to ask others not to smoke in your home or car.  

Also, because of its many effects on the body, excessive alcohol consumption and alcoholism are linked with higher cholesterol levels. Limiting your drinking or stopping altogether can help control levels.

Age and Sex

Your age and sex can also have a significant influence on LDL levels. As both men and women age, they usually rise. Men tend to have higher LDL levels than women during younger years (ages 20 to 59). In contrast, women consistently had higher values of LDL after midlife (age 60).

For women, going through menopause can also influence LDL. The risk of having high cholesterol premenopause is significantly lower. This is why more frequent monitoring of LDL is recommended for menopausal women.

Genetics

As with a great deal of health conditions, a family history of high cholesterol increases the risk of your developing it. High LDL levels due to genetics, a condition called familial hypercholesterolemia (FH), occurs in one out of every 500 people. This condition is especially concerning because it's often undetected and is associated with early heart attack, stroke, and premature death.

In these cases, the gene that encodes the receptor protein for LDL cholesterol—essential for clearing it out of the bloodstream—malfunctions. If this gene is acquired from one parent, a condition called heterogenous FH, about half of these proteins are inactive. In turn, homogenous FH occurs when both parents carry the faulty gene.

Tough-to-treat cases of high cholesterol, in particular, may call for genetic screening for FH. Furthermore, presence of high cholesterol in a family member, or family history of early heart disease, can also prompt scrutiny.   

Race and Ethnicity

According to a growing body of research, race and ethnicity is also a factor in high cholesterol levels. While all races and ethnicities can develop high LDL, there are differences based on status. Here's a quick breakdown:

• African Americans: High cholesterol is seen in nearly even amounts among African American men and women, occurring in 10.6% of the former, and 10.3% of the latter.
• Hispanics: Among Hispanic men, 13.1% develop high cholesterol, though this number is 9% among Hispanic women.
• Non-Hispanic Asians: Asian men and women also have quite comparable rates of high cholesterol. It occurs in 11.3% of Asian men and 10.3% of Asian women.
• Non-Hispanic whites: The highest percentage of elevated cholesterol is seen in white women, with 14.8% estimated to have it. This drops to 10.9% among white men.

Medications

Medications you've been prescribed can also cause LDL levels to be elevated. This can be especially challenging as drugs for heart conditions and high blood pressure, among other related conditions, are on the list. Prior to any prescription, your doctor will have to carefully outline the risks and benefits.

So what types of drugs raise LDL levels? There are quite a few:

• Cardiovascular drugs: Some drugs for heart disease and blood pressure can cause LDL levels to rise. These include loop diuretics [Bumex (bumetanide) Edecrin (ethacrynic acid), and others], thiazide diuretics [Zaroxolyn, (metalozone), Lozol (indapamide), among others], and sodium-glucose cotransporter 2 (SGLT2) inhibitors [like Invokana (canagliflozin) and Farxiga (dapagliflozin)].
• Steroids: Some types of steroids and steroid hormones, typically used to take on inflammation, can also boost cholesterol. Higher LDL is associated with the androgen, Danocrine (danazol), anabolic steroids (synthesized version of the male hormone, testosterone), and some corticosteroids like Prednisone Intensol (prednisone) and Orapred (prednisolone).
• Antiviral therapy: Drugs taking on viral infections like human immunodeficiency virus (HIV) and hepatitis C can also raise LDL. These include both protease inhibitors, such as Viracept (nelfinavir) and Incivek (telaprevir), and direct-acting antivirals like Harvoni (ledipasvir) and Fuzeon (enfuvirtide).
• Immunosuppressants: Some immunosuppressing drugs, especially cyclosporine and tacrolimus, used to prevent infection in organ transplants, also boost levels of LDL. Corticosteroids can also have an anti-inflammatory and immune system moderating effects.
• Other drugs: Some drugs acting on the brain and central nervous system (CNS) may directly affect LDL. Among these are anticonvulsant drugs used for epilepsy, Alzheimer's disease, and other conditions, like Depakote (valproic acid) and Topamax (topiramate).

Many different types of drugs can affect LDL, so careful monitoring of prescriptions is necessary when managing high cholesterol.

Other Health Conditions

Finally, high cholesterol can also be caused by a range of other health conditions, disorders, or diseases you may have. These include:

• Type 2 diabetes: One of the main effects of diabetes is insufficient production of insulin, which breaks down sugars. This limits the body's ability to process LDL.
• Liver disease: Liver problems like liver cirrhosis can also have an immediate impact on cholesterol levels.
• Kidney diseases: Since the kidneys play a central role in cleaning out your bloodstream, problems here, such as chronic kidney disease, will also cause spikes in cholesterol levels.
• Pregnancy: Cholesterol levels tend to be higher in pregnant women. The situation is usually monitored, as high levels during this time increases the risk of certain complications.
• Thyroid problems: Hypothyroidism—the underactivity of the thyroid gland—is known to dramatically boost LDL levels. If yours are high, you'll need to have your thyroid checked.

FAQs

What makes LDL cholesterol too high?

A range of medical and lifestyle factors cause high LDL, including:

• Diet: Diets high in saturated fats, salts, and cholesterol (as found in fatty meats, some processed foods, dairy, and cured meats) and low in healthy proteins (fish, nuts, avocados, and others) and fiber (such as leafy vegetables, and apples) can lead to high LDL.
• Lack of physical activity: Not getting enough exercise and being sedentary contributes to weight gain and can also push levels up. You may see higher LDL if you don't get a minimum of 30 minutes a day of activity.
• Weight status: Being overweight or obese greatly increases the chances of developing high LDL. Even modest gains in weight can push levels to unhealthy ranges.
• Alcohol and tobacco: Smoking and drinking are both associated with high cholesterol, among many other detrimental effects on health.
• Genetics: High LDL can be inherited, a condition called familial hypercholesterolemia (FH). The severity of FH ranges, but those with the homozygous form—in which both parents are carriers of the faulty gene—may have extremely high amounts of this type of cholesterol.
• Medications: Taking several classes of drugs can lead to spikes in LDL. These include those for heart disease, high blood pressure, inflammation, certain viruses, and seizures, among other conditions. Talk to your doctor about how these prescriptions may impact cholesterol.
• Health conditions: Diseases and conditions that cause high LDL include type 2 diabetes, pregnancy, chronic kidney disease, and hypothyroidism.

Which foods increase LDL cholesterol levels?

Your diet plays a massive role in determining your cholesterol levels. Foods high in trans fats, saturated fats, and salts can be especially dangerous. These include:

• Red meats
• Whole-fat milk and butter
• Donuts, cookies, crackers, and other baked goods
• Fast foods
• Partially-hydrogenated vegetable oils
• Chicken with the skin on
• Cured or processed meats

Many food items you find in the store may have trans and saturated fats and high sodium, so make sure to carefully read the nutrition information before buying.

What has the biggest impact on LDL cholesterol?

Contrary to the long-held belief that dietary cholesterol itself is a major cause of high LDL, evidence suggests a weaker link. It's still a good idea to steer clear of dietary cholesterol, but that intake isn't the biggest influence. The current understanding is that the specific mix of carbohydrates and fats in your diet is the biggest factor in determining your LDL levels.

A Word From Verywell

Given how fundamental cholesterol is to the processes of the body and the function of the circulatory system, it's little wonder that many factors can cause high LDL. Since there are so many dangers associated with it, however, figuring out what specific behaviors, medications, or other issues are causing the problem can be key in solving it.

Ultimately, there is no singular method to taking on high LDL; what works for some, doesn't work as well for others. Getting this to a healthy level is a journey, rather than an event. That said, with the support of loved ones and the guidance of health professionals, your cholesterol can be effectively managed. The benefits of that work, of course, are boundless.