Dyslipidaemia is a common condition affecting lipid levels in the blood that significantly increases the risk of heart disease and stroke, yet many people with abnormal cholesterol levels remain unaware of their condition or untreated.

Understanding Dyslipidaemia

Dyslipidaemia refers to abnormal levels of lipids, which are fatty substances, in the bloodstream. This condition occurs when there are unhealthy amounts of one or more types of fats circulating in your blood. The term encompasses several possible problems with blood fats, including having too much of certain types or not enough of others. Unlike many health conditions that cause obvious symptoms, dyslipidaemia typically develops silently over time, making regular screening particularly important for early detection and management.^[1]

The condition involves three main types of lipids that doctors measure when assessing cardiovascular health. These include low-density lipoprotein cholesterol, commonly called LDL or “bad” cholesterol, which can build up on artery walls and form dangerous blockages. There is also high-density lipoprotein cholesterol, known as HDL or “good” cholesterol, which helps remove harmful cholesterol from the bloodstream. Finally, triglycerides are fats that come from calories you consume but don’t immediately burn for energy. When triglyceride levels become too high, they also contribute to cardiovascular risk.^[2]

Understanding how these lipids work in your body helps explain why maintaining proper balance is so important. Your liver naturally produces cholesterol because your body needs it for essential functions like digesting food, producing hormones, and maintaining healthy cells. However, you also consume cholesterol through foods, particularly those from animal sources like meat and dairy products. Since your liver already makes all the cholesterol your body requires, additional cholesterol from dietary sources becomes excess. This surplus, combined with other factors, can lead to unhealthy lipid levels that threaten cardiovascular health.^[3]

Epidemiology and Global Impact

Dyslipidaemia represents a massive global health challenge affecting hundreds of millions of people worldwide. More than one-third of the world’s population has elevated blood cholesterol levels, making this one of the most prevalent health conditions affecting adults today. The scale of this problem continues to grow as populations age and lifestyle factors change across different regions.^[7]

In the United States alone, the statistics are striking. Approximately 93 million American adults over age 20 have total cholesterol levels exceeding the recommended limit of 200 milligrams per deciliter. This means that nearly one in three adults carries an elevated cardiovascular risk due to high cholesterol. Despite the availability of effective treatments, many people with abnormal lipid levels remain either undiagnosed or inadequately treated, leaving them vulnerable to serious health complications.^[3]

The global burden of dyslipidaemia is staggering when measured in terms of mortality and disability. This condition contributes to approximately 4.4 million deaths annually worldwide. The impact extends beyond mortality statistics, as dyslipidaemia significantly contributes to the development of cardiovascular diseases that limit quality of life and create enormous economic burdens on healthcare systems. The condition has risen dramatically as a risk factor for death over recent decades, climbing from the 15th leading risk factor for mortality in 1990 to the 8th position by 2019.^[7]

Geographic variations in dyslipidaemia prevalence exist, though the condition affects populations across all regions and income levels. In Iran, for example, research has documented that hypercholesterolaemia, hypertriglyceridaemia, high LDL cholesterol, and low HDL cholesterol affect 41.6%, 46.0%, 35.5%, and 43.9% of the population respectively. Other studies have found that dyslipidaemia affects between 83% and 87% of certain populations, with rates being particularly high among people who already have cardiovascular disease.^[8]

Causes of Dyslipidaemia

Dyslipidaemia develops through two main pathways, which doctors classify as either primary or secondary causes. Understanding these different origins helps in determining the most appropriate treatment approach for each person. Primary dyslipidaemia stems from inherited genetic factors, while secondary dyslipidaemia arises from lifestyle choices or other medical conditions that alter how your body processes fats.^[1]

Primary dyslipidaemia occurs when genetic mutations affect lipid metabolism, the complex process by which your body handles fats. These inherited conditions are passed down through families and can cause abnormal lipid levels from a young age. One example is familial hypercholesterolaemia, an autosomal dominant genetic condition caused by a defect on chromosome 19. People with this inherited disorder typically develop very high cholesterol levels and face increased risk of early heart disease. Another common inherited form is familial combined hyperlipidaemia, which causes elevations in both LDL cholesterol and triglycerides. People with this condition may develop problems during their teens or twenties and face higher risks of coronary artery disease at younger ages than the general population.^[1][2]

Secondary dyslipidaemia develops as a consequence of other factors rather than being directly inherited. Lifestyle factors play a major role in secondary dyslipidaemia, with diet being particularly important. Consuming foods high in saturated fats and trans fats significantly raises cholesterol levels. These unhealthy fats are found primarily in red meat, full-fat dairy products like butter and cream, coconut oil, palm oil, and many commercially prepared baked goods and deep-fried foods. Physical inactivity also contributes to abnormal lipid levels, as does obesity, which affects how the body processes and stores fats.^[4]

Several medical conditions can trigger secondary dyslipidaemia by disrupting normal lipid metabolism. Diabetes mellitus commonly causes abnormal lipid levels because high blood sugar affects how the body handles fats. Hypothyroidism, a condition where the thyroid gland produces insufficient hormones, can elevate cholesterol levels. Kidney disease and liver disease both interfere with normal lipid processing. Even excessive alcohol consumption can trigger dyslipidaemia, particularly by raising triglyceride levels. Certain medications, including some drugs used to treat high blood pressure, can also affect lipid levels as an unintended side effect.^[9]

Risk Factors for Developing Dyslipidaemia

Numerous factors increase a person’s likelihood of developing abnormal lipid levels. Some of these risk factors cannot be changed, while others can be modified through lifestyle adjustments or medical treatment. Recognizing these risk factors helps identify people who should undergo more frequent screening and potentially more aggressive treatment to prevent cardiovascular complications.^[6]

Family history represents an important non-modifiable risk factor. If your parents, siblings, or other close relatives have dyslipidaemia or experienced premature coronary artery disease, your own risk increases substantially. This elevated risk reflects both shared genetic factors and potentially similar environmental exposures within families. Age also plays a role, as lipid levels tend to change as people grow older, with risk generally increasing with advancing years.^[6]

Behavioural and lifestyle factors that increase dyslipidaemia risk are modifiable, meaning people can change them to reduce their risk. Current cigarette smoking significantly affects lipid levels and cardiovascular health through multiple mechanisms. Obesity, particularly when body mass index exceeds 30 kilograms per square meter, strongly predicts abnormal lipid levels. Dietary patterns high in saturated fats, trans fats, and cholesterol while low in fruits, vegetables, and whole grains promote dyslipidaemia. Physical inactivity compounds these effects, as regular exercise helps maintain healthy lipid profiles.^[6]

Several medical conditions substantially increase dyslipidaemia risk. People with diabetes mellitus face particularly high risk, as the metabolic disturbances of diabetes directly affect lipid processing. Hypertension, or high blood pressure, often coexists with abnormal lipid levels as part of broader metabolic dysfunction. Chronic kidney disease impairs the body’s ability to properly process and eliminate lipids. Other conditions that increase risk include atherosclerosis, erectile dysfunction, chronic obstructive pulmonary disease, inflammatory bowel disease, and even recent COVID-19 infection. Women who experienced hypertensive disorders during pregnancy also face increased risk.^[6]

Symptoms and Clinical Presentations

One of the most challenging aspects of dyslipidaemia is that most people with the condition experience no symptoms at all. High cholesterol and elevated triglycerides typically develop silently over many years without causing any noticeable physical changes or discomfort. This absence of warning signs means that millions of people live with dangerously high lipid levels without realizing they have a problem. By the time symptoms do appear, they usually reflect serious cardiovascular complications that have already developed, such as heart attack or stroke.^[2]

The lack of symptoms explains why routine screening through blood tests is so crucial. Without testing, there is no way to know whether your lipid levels fall within the healthy range. Most people only discover they have dyslipidaemia when their doctor orders blood work as part of a general health check-up or when investigating other health concerns. This highlights the importance of regular medical visits that include lipid screening, especially for people with risk factors.^[3]

In rare cases, people with severely elevated lipid levels may develop visible physical signs. Some individuals with very high cholesterol develop yellowish deposits of fat under the skin called xanthomas, which can appear on tendons, particularly around the elbows, knees, and Achilles tendon. Similarly, xanthelasmata are yellowish patches that can appear on the eyelids. A condition called arcus cornealis, a whitish or grayish ring around the cornea of the eye, sometimes develops in people with high cholesterol, particularly if it appears before age 45. However, these physical signs occur only in a minority of cases, typically when lipid levels are extremely elevated or in certain genetic conditions.^[6]

The real danger of dyslipidaemia lies in its long-term consequences rather than immediate symptoms. Over time, elevated LDL cholesterol causes fatty deposits called plaque to accumulate inside artery walls, a process called atherosclerosis. These plaques gradually narrow the arteries, restricting blood flow to vital organs. When plaque ruptures or a blood clot forms around it, the artery can become completely blocked. If this happens in arteries supplying the heart, a heart attack occurs. If blockage happens in arteries feeding the brain, a stroke results. The symptoms people experience at that point reflect these acute cardiovascular events rather than the underlying dyslipidaemia itself.^[3]

Prevention Strategies

Preventing dyslipidaemia or stopping it from worsening involves a combination of healthy lifestyle habits, regular monitoring, and in some cases, medical intervention. Because lifestyle factors play such a major role in secondary dyslipidaemia, most prevention strategies focus on modifiable behaviours that influence lipid levels. These preventive measures benefit everyone, regardless of whether they currently have abnormal lipid levels or not.^[12]

Dietary changes represent the foundation of dyslipidaemia prevention. Following a heart-healthy eating pattern means choosing a variety of fresh, unprocessed foods while limiting items that raise cholesterol and triglycerides. This involves reducing saturated fat intake, which means eating less red meat, full-fat dairy products like butter and cheese, and tropical oils such as coconut and palm oil. Trans fats should be eliminated entirely, which means avoiding partially hydrogenated vegetable oils found in many margarines and commercially baked products. Instead, the diet should emphasize fruits, vegetables, whole grains, legumes, nuts, and seeds. Lean proteins and foods containing healthy unsaturated fats, such as fatty fish rich in omega-3 fatty acids, olive oil, and avocados, should replace less healthy options.^[17]

Increasing dietary fibre intake specifically helps lower cholesterol levels. Soluble fibre, found in foods like oatmeal, kidney beans, Brussels sprouts, apples, and pears, can reduce the absorption of cholesterol into the bloodstream. This type of fibre acts like a sponge in the digestive system, binding to cholesterol and helping remove it from the body before it enters circulation. Aim to include fibre-rich foods at every meal to maximize this beneficial effect.^[17]

Regular physical activity plays a crucial role in maintaining healthy lipid levels. Exercise helps raise HDL cholesterol, the “good” type that removes harmful cholesterol from arteries. Physical activity also helps control weight, reduces triglycerides, and improves overall cardiovascular health through multiple mechanisms. Aim for at least 150 minutes of moderate-intensity aerobic activity each week, which could include brisk walking, swimming, cycling, or dancing. Even smaller amounts of activity provide benefits, so any movement is better than none. Building physical activity into daily routines, such as taking stairs instead of elevators or walking instead of driving for short trips, helps accumulate beneficial movement throughout the day.^[12]

Maintaining a healthy body weight prevents dyslipidaemia and improves existing lipid abnormalities. Even modest weight loss of 5% to 10% of body weight can produce meaningful improvements in lipid levels for people who are overweight or obese. Weight management works best when approached through a combination of dietary changes and increased physical activity rather than relying on either strategy alone. The goal should be gradual, sustainable weight loss rather than rapid changes that prove difficult to maintain long-term.^[17]

Avoiding tobacco in all forms is essential for preventing dyslipidaemia and reducing cardiovascular risk. Smoking damages blood vessels, lowers HDL cholesterol, and increases the likelihood that LDL cholesterol will form dangerous plaques in arteries. For people who currently smoke, quitting represents one of the most powerful steps they can take to improve their cardiovascular health. Within months of quitting, HDL cholesterol levels begin to improve.^[12]

Limiting alcohol consumption helps prevent elevated triglycerides and other metabolic problems. While some research suggests moderate alcohol intake may have cardiovascular benefits for some people, excessive drinking clearly raises triglyceride levels and contributes to other health problems. People who drink alcohol should do so only in moderation, which means no more than one drink per day for women and two drinks per day for men.^[9]

Regular screening enables early detection of dyslipidaemia before it causes complications. Adults age 20 and older should have their cholesterol checked at least every five years. For people aged 45 and older, cholesterol screening can be included as part of a comprehensive heart health check. Aboriginal and Torres Strait Islander peoples should begin cholesterol screening from age 18 due to higher cardiovascular risk in these populations. People with risk factors such as diabetes, hypertension, family history of heart disease, or obesity may need more frequent testing.^[5]

Pathophysiology: How Dyslipidaemia Affects the Body

Understanding how dyslipidaemia develops and damages the body requires examining the normal processes of lipid metabolism and what happens when these processes malfunction. Lipids cannot dissolve in blood plasma because they are fatty substances and blood is primarily water. To solve this problem, the body packages lipids inside protein shells called lipoproteins, which allow fats to travel through the bloodstream to where they are needed.^[1]

Different types of lipoproteins perform specific functions. Chylomicrons transport dietary fats absorbed from the intestines. Very low-density lipoproteins (VLDL) carry triglycerides synthesized by the liver. As VLDL particles deliver triglycerides to tissues, they transform into intermediate-density lipoproteins (IDL) and eventually into low-density lipoproteins (LDL), which primarily carry cholesterol to cells throughout the body. Finally, high-density lipoproteins (HDL) collect excess cholesterol from tissues and transport it back to the liver for disposal. This system normally maintains balanced lipid levels that meet the body’s needs without causing harm.^[13]

Dyslipidaemia occurs when this system becomes imbalanced through impaired lipoprotein synthesis, secretion, or clearance. When LDL cholesterol levels become too high, excess particles circulate in the bloodstream for extended periods. These LDL particles can penetrate the walls of arteries, particularly at sites where the protective inner lining has been damaged by factors such as high blood pressure, smoking, or inflammation. Once inside the artery wall, LDL particles undergo chemical changes through a process called oxidation, which makes them harmful to surrounding tissues.^[1]

The body’s immune system recognizes oxidized LDL as foreign material and responds by sending specialized white blood cells called macrophages to consume the modified cholesterol particles. These macrophages become engorged with lipids, transforming into what scientists call “foam cells” because of their foamy appearance under the microscope. Foam cells accumulate in the artery wall, releasing inflammatory chemicals that attract more immune cells and perpetuate a cycle of inflammation and lipid accumulation. Over time, this process creates fatty deposits called atherosclerotic plaques.^[8]

As plaques grow, they progressively narrow the artery channel, reducing blood flow to tissues and organs downstream. The plaque itself consists of a lipid-rich core covered by a fibrous cap. This cap can become unstable and prone to rupture, particularly when it is thin and the underlying lipid core is large. When a plaque ruptures, it exposes highly inflammatory material to the bloodstream, triggering rapid formation of a blood clot. This clot can completely block the already narrowed artery within minutes, cutting off blood supply to vital organs. If this occurs in a coronary artery feeding the heart muscle, the result is a heart attack. If it happens in an artery supplying the brain, a stroke occurs.^[7]

Low HDL cholesterol contributes to cardiovascular disease through different mechanisms. HDL normally performs a process called “reverse cholesterol transport,” removing excess cholesterol from peripheral tissues including artery walls and transporting it to the liver for elimination. When HDL levels are too low, this protective mechanism becomes less efficient, allowing cholesterol to accumulate in arterial walls more readily. HDL also has anti-inflammatory and antioxidant properties that help protect against atherosclerosis through mechanisms beyond simple cholesterol removal.^[5]

Elevated triglycerides affect cardiovascular health through multiple pathways. High triglyceride levels often occur alongside other metabolic abnormalities including low HDL cholesterol, small dense LDL particles that are particularly prone to causing atherosclerosis, insulin resistance, and inflammation. VLDL particles, which carry triglycerides, can themselves contribute to atherosclerosis. Additionally, very high triglyceride levels can cause a separate set of complications including acute pancreatitis, a painful and potentially dangerous inflammation of the pancreas.^[5]

The concept of “residual risk” has become increasingly recognized in dyslipidaemia research. Even among people who achieve target LDL cholesterol levels through treatment, approximately 40% still experience major cardiovascular events. This suggests that other factors beyond LDL cholesterol contribute to cardiovascular disease. These may include elevated triglycerides, low HDL cholesterol, inflammatory processes, insulin resistance, and other metabolic abnormalities that often cluster together. This residual risk explains why comprehensive management of all cardiovascular risk factors, not just cholesterol, is essential for optimal protection.^[7]