Many people may feel anxious after being told they have high LDL cholesterol during a health check-up. LDL cholesterol is also known as “bad cholesterol,” and leaving it untreated at high levels can have serious consequences for future health. However, with the right knowledge and appropriate measures, improvement is definitely achievable. This article explains everything from the basics of LDL cholesterol, its reference values, causes of high levels, associated risks, to specific methods for lowering it. Please read through to the end for your health management.
What is LDL Cholesterol?
Cholesterol is an important type of lipid in our bodies. It plays various essential roles in vital activities, such as being a component of cell membranes, a material for hormones, and a precursor to bile acids necessary for fat digestion and absorption. Blood vessels in the blood do not exist alone but are transported throughout the body bound to proteins called lipoproteins. There are several types of these lipoproteins, one of which is LDL (Low-Density Lipoprotein).
Why it is Called “Bad Cholesterol”
LDL cholesterol is called “bad” for a reason related to its properties. LDL is responsible for transporting cholesterol produced in the liver to cells throughout the body. However, when there is an excess of LDL cholesterol in the blood, it tends to enter the walls of blood vessels. Accumulated LDL cholesterol in the vascular walls can become oxidized, leading to inflammation and promoting the progression of atherosclerosis (a condition where blood vessels harden and narrow). Since atherosclerosis can cause serious diseases like heart disease and stroke, as described later, LDL cholesterol is considered “bad.”
Difference from HDL Cholesterol and VLDL Cholesterol
Besides LDL cholesterol, other lipoproteins exist in the blood, such as HDL (High-Density Lipoprotein) cholesterol and VLDL (Very Low-Density Lipoprotein) cholesterol. Each has a different role.
| Type of Cholesterol | Role | Common Name |
|---|---|---|
| LDL Cholesterol | Transports cholesterol from the liver to the whole body. Excess can accumulate in vascular walls and cause atherosclerosis. | Bad Cholesterol |
| HDL Cholesterol | Collects excess cholesterol from throughout the body and returns it to the liver. Also involved in removing cholesterol from vascular walls, helping to suppress atherosclerosis. | Good Cholesterol |
| VLDL Cholesterol | Transports triglycerides produced in the liver to the body. Also a precursor to LDL cholesterol. | (No specific common name) |
HDL cholesterol is called “good cholesterol” because it collects excess cholesterol from blood vessels and cells throughout the body and returns it to the liver. If there is too little good cholesterol, bad cholesterol tends to accumulate in the vascular walls, making HDL cholesterol levels also important in health management. VLDL cholesterol mainly transports triglycerides, but it transforms into LDL cholesterol, so high VLDL levels also require attention. The balance of these cholesterols significantly affects vascular health.
LDL Cholesterol Reference Values and Normal Levels
Knowing what LDL cholesterol levels are considered normal and which require attention is crucial for understanding your health status. Generally, the reference range for LDL cholesterol in blood tests varies slightly depending on the test method and medical institution, but it is typically considered below 140 mg/dL for healthy adults. However, this is just a general guideline, and there can be variations with age. For example, cholesterol levels tend to increase slightly with age. Nevertheless, there are no strict “normal levels” defined by age, and what matters is determining the target value considering individual risk factors.
Age-Specific LDL Cholesterol Reference Values
While general guidelines exist, there are no universally accepted strict age-specific “normal” ranges for LDL cholesterol. However, as people age, their risk of atherosclerotic diseases tends to increase, and the focus shifts more towards individual risk factors rather than just age-based averages. Healthcare providers interpret LDL levels in the context of a person’s overall health profile.
Target Values Based on Cardiovascular Disease Risk
The most crucial aspect of managing LDL cholesterol is the “target value,” which considers the risk of future cardiovascular events like heart disease and stroke. Guidelines, such as the Japan Atherosclerosis Society’s Guidelines for Prevention of Atherosclerotic Cardiovascular Diseases, set stricter LDL cholesterol targets based on an individual’s risk factors (smoking, high blood pressure, diabetes, chronic kidney disease, history of cardiovascular disease, old age, etc.).
| Risk Category | LDL Cholesterol Target Value |
|---|---|
| Low Risk | Below 140 mg/dL |
| Moderate Risk | Below 120 mg/dL |
| High Risk (e.g., Coronary Artery Disease) | Below 100 mg/dL |
| History of Coronary Artery Disease | Below 80 mg/dL |
When assessing whether your LDL cholesterol level is high or low, it’s essential not only to compare it to the general reference range but also to understand which risk category you fall into. Individuals with higher risk require more aggressive measures to lower LDL cholesterol. Always consult with a doctor to confirm your specific target value.
Definition of High LDL Cholesterol
Generally, an LDL cholesterol level of 140 mg/dL or higher is often diagnosed as “Hyper-LDL Cholesterolmia.” This is a type of dyslipidemia (formerly known as hyperlipidemia). Hyper-LDL Cholesterolmia itself usually has almost no subjective symptoms, so it is most often first detected during a health check-up. However, if left untreated, it silently promotes atherosclerosis, increasing the risk of developing serious diseases in the future. Therefore, if you are told your level is high, it is crucial not to underestimate it but to investigate the cause and start appropriate measures immediately.
Causes of High LDL Cholesterol
High LDL cholesterol is not caused by a single factor but results from a complex interplay of various elements. The main causes include the influence of diet and lifestyle, as well as genetic predisposition. Understanding these causes helps in taking effective countermeasures.
Influence of Diet and Lifestyle
The most significant factors influencing high LDL cholesterol levels are daily diet and lifestyle habits.
In particular, excessive consumption of foods rich in saturated fatty acids and trans fatty acids is a major cause of elevated LDL cholesterol. Saturated fatty acids are abundant in animal fats such as meat fat, butter, cream, cheese, and lard. Trans fatty acids are found in margarine, shortening, and processed foods made with them, such as bread, cakes, biscuits, and french fries.
Furthermore, excessive intake of foods high in cholesterol itself (egg yolks, fish roe, liver, etc.) can potentially affect LDL cholesterol levels, although it is generally considered to have less impact than saturated or trans fats. However, there are individual differences in body type.
In addition, obesity due to overeating and lack of exercise also cause LDL cholesterol to rise. When calorie intake consistently exceeds calories burned, body fat increases, negatively affecting lipid metabolism.
Smoking not only increases LDL cholesterol levels but also lowers HDL (good) cholesterol and directly damages blood vessels, making it a strong risk factor for promoting atherosclerosis.
Excessive alcohol consumption can also increase triglycerides and indirectly disrupt the balance of LDL cholesterol.
Lifestyle irregularities such as stress and lack of sleep are also suggested to affect hormone balance and negatively impact lipid metabolism.
Genetic Factors and Secondary Hypercholesterolemia
In some cases, high LDL cholesterol is significantly influenced by genetic factors, which are inherited traits, in addition to lifestyle habits. A representative example is “familial hypercholesterolemia.” This is a disease caused by a mutation in the gene responsible for taking up LDL cholesterol from the blood, resulting in extremely high LDL cholesterol levels despite diet and exercise efforts. Even inheriting an abnormal gene from one parent can lead to significantly higher LDL cholesterol levels than usual, with atherosclerosis progressing faster from a young age. If there is a history of heart disease in the family at a young age, it is important to consider the possibility of familial hypercholesterolemia and get tested.
Also, LDL cholesterol can be elevated due to other diseases (e.g., hypothyroidism, kidney diseases such as nephrotic syndrome, some liver diseases, use of steroid medications, etc.). This is called secondary hypercholesterolemia. In such cases, treating the underlying disease is expected to improve LDL cholesterol levels.
Risks and Symptoms of High LDL Cholesterol
The most significant problem with hyper-LDL cholesterolmia is that it increases the risk of developing serious diseases in the future. However, in most cases, high LDL cholesterol itself has no subjective symptoms.
Progression of Atherosclerosis
As mentioned earlier, excessive LDL cholesterol accumulates in the vascular walls and undergoes changes like oxidation, forming plaque (atheroma). This plaque protrudes into the inside of the blood vessel, narrowing the passage (lumen). This is atherosclerosis. Atherosclerosis can occur in blood vessels throughout the body, but it is particularly serious when it happens in the blood vessels of the heart or brain. If the plaque ruptures, a blood clot (thrombus) is likely to form there, which can completely block the blood vessel.
Risk of Heart Disease, Stroke, and Other Diseases
When the blood vessels of the heart (coronary arteries) narrow or become blocked due to atherosclerosis, the heart muscle does not receive enough blood or oxygen, leading to angina or myocardial infarction. These diseases are often life-threatening and can result in lasting disabilities.
When atherosclerosis progresses in the brain’s blood vessels, causing stenosis or occlusion, blood supply to the brain is disrupted, leading to cerebral infarction. Furthermore, if a weakened brain blood vessel ruptures due to atherosclerosis, it causes cerebral hemorrhage. These are collectively called stroke. Stroke also has a high potential for being life-threatening and can leave severe sequelae such as paralysis or speech disorders.
High LDL cholesterol is a strong risk factor for these atherosclerotic diseases, including heart disease and stroke, which are among the leading causes of death in Japan. Especially when combined with other risk factors like high blood pressure, diabetes, and smoking, the risk increases even further.
Presence or Absence of Subjective Symptoms
The most frightening aspect of hyper-LDL cholesterolmia is that it usually has no subjective symptoms. Even when levels are very high, non-specific symptoms like fatigue or headache typically do not appear. Symptoms such as angina attacks (chest pain) or stroke symptoms (paralysis in limbs, slurred speech, etc.) usually appear only when atherosclerosis has significantly progressed, resulting in reduced blood flow to organs. This means that by the time symptoms appear, the disease is likely already quite advanced. Therefore, even if you have no symptoms, it is crucial to have regular blood tests to monitor your LDL cholesterol levels. This is extremely important for early detection and prevention.
How to Lower LDL Cholesterol
To lower LDL cholesterol, the main approach involves lifestyle changes, particularly diet therapy and exercise therapy. If these do not help reach the target value, or if the risk is very high, medication may be considered.
Improvement Through Diet Therapy
Diet is one of the factors that most directly affects LDL cholesterol levels. Balancing your diet and adjusting the intake of specific foods can be effective.
Foods That Lower Cholesterol
Foods that are particularly helpful in lowering LDL cholesterol include those rich in soluble dietary fiber. Soluble fiber helps to adsorb cholesterol and bile acids (made from cholesterol) in the intestines and aids in their excretion from the body in feces. It is abundant in foods like oatmeal, barley, seaweeds such as wakame and konbu, konnyaku, mushrooms, fruits like apples and citrus, and legumes.
Also recommended are foods high in unsaturated fatty acids. Omega-3 fatty acids (EPA and DHA) found in blue fish, in particular, are known to lower triglycerides and are also believed to help balance LDL cholesterol. Plant oils like flaxseed oil and perilla oil also contain omega-3 fatty acids. Omega-9 fatty acids found in olive oil are also said to help lower LDL cholesterol.
Vegetable protein and isoflavones in soy products (tofu, natto, soy milk, etc.) are also expected to have cholesterol-lowering effects.
Furthermore, foods rich in polyphenols (green tea, cocoa, etc.) are thought to help prevent the oxidation of LDL cholesterol.
Foods and Components to Avoid
It is important to limit the intake of foods high in saturated fatty acids and trans fatty acids, which are major causes of elevated LDL cholesterol. Fatty cuts of meat, chicken skin, processed meats (sausages, bacon, etc.), butter, cream, lard, pastries, fast food, and fried foods are typical examples of foods high in these components.
Excessive intake of foods high in cholesterol (egg yolks, fish roe, monkfish liver, etc.) also needs attention. However, the cholesterol in these foods does not necessarily directly translate into elevated blood LDL cholesterol levels, as the body has mechanisms to regulate cholesterol synthesis. Nevertheless, individual differences in body type are significant, so it is wise for those with high LDL cholesterol to be mindful of not consuming too much of these foods just in case.
Cooking methods are also important. Choosing cooking methods that use less oil, such as steaming, boiling, or grilling, can reduce the intake of excess fats compared to frying or stir-frying.
Practice of Exercise Therapy
Regular, moderate exercise can not only lower LDL cholesterol but also potentially increase HDL (good) cholesterol. Aerobic exercise is particularly effective. It is recommended to maintain exercise that makes you breathe slightly harder, such as walking, jogging, cycling, or swimming, for at least 30 minutes per session, three or more times a week. If you are not used to exercising, start with about 10 minutes of walking per day and gradually increase the duration and frequency.
In addition to aerobic exercise, incorporating strength training can also potentially improve lipid metabolism indirectly by increasing basal metabolism and making it easier to reduce body fat.
The key is to find an exercise you can continue without overexertion and enjoy doing it consistently.
Importance of Quitting Smoking
Smoking is one of the most powerful risk factors that not only raises LDL cholesterol levels and lowers HDL cholesterol levels but also directly damages the vascular endothelium, promoting atherosclerosis. If individuals with high LDL cholesterol continue to smoke, the progression of atherosclerosis accelerates significantly. Alongside efforts to lower LDL cholesterol, quitting smoking is essential. If quitting smoking is difficult, visiting a smoking cessation clinic or using smoking cessation aids can be effective.
About Drug Therapy
If LDL cholesterol levels do not reach the target value after several months of lifestyle improvements such as diet and exercise therapy, or if the risk is assessed as very high (e.g., having a history of cardiovascular disease), drug therapy may be considered.
The most commonly used type of medication to lower LDL cholesterol is a class of drugs called statins. Statins effectively lower blood LDL cholesterol levels by suppressing cholesterol synthesis in the liver. There are also other types of medications, such as those that inhibit cholesterol absorption in the small intestine or promote bile acid excretion.
The choice of medication and dosage is determined by the doctor based on the patient’s LDL cholesterol level, other risk factors, comorbidities, and overall health status. Even when starting drug therapy, it is important to continue lifestyle improvements. Do not change the dosage or stop taking the medication on your own; always follow your doctor’s instructions.
When LDL Cholesterol is Low
While high LDL cholesterol is often emphasized as a problem, extremely low levels can also potentially impact health.
Causes of Low LDL Cholesterol
Causes of low LDL cholesterol, like high levels, can be several.
They can be due to genetic factors (e.g., very rare conditions like abetalipoproteinemia) or insufficient cholesterol production due to malnutrition (extreme fat restriction or malabsorption).
Also, LDL cholesterol levels can decrease due to specific diseases (e.g., hyperthyroidism, severe liver disease, chronic inflammatory conditions).
Health Effects of Low LDL Cholesterol
The effects of extremely low LDL cholesterol are not as clearly established as those of high LDL cholesterol. However, it is suggested that persistently very low levels of cholesterol, which is a component of cell membranes and a material for hormones, could potentially affect various bodily functions. For instance, there are suggestions of impacts on immune function and the nervous system, and endocrine system.
However, if your LDL cholesterol is just slightly below the reference range in a general health check-up, there is usually little need for excessive worry. The important thing is to investigate why it is low. If you have other subjective symptoms or persistently low values in tests, be sure to consult a doctor to check for any underlying diseases.
LDL Cholesterol Testing and Health Management
Since hyper-LDL cholesterolmia has no subjective symptoms, regular testing is essential to know your levels.
Necessity of Regular Blood Tests
As mentioned earlier, a state of high LDL cholesterol silently promotes atherosclerosis, also known as a silent killer. It is often too late once symptoms appear. Therefore, even without symptoms, it is strongly recommended to have regular health check-ups or comprehensive medical check-ups at least once a year and undergo lipid tests, including LDL cholesterol. Those with a family history of cardiovascular disease or other risk factors (high blood pressure, diabetes, smoking, etc.) should be even more proactive in getting tested. Knowing your test results allows you to understand your current health status, predict future risks, and start appropriate measures early.
Consulting a Doctor and Visiting Specialized Institutions
If an abnormality in your LDL cholesterol level is pointed out during a health check-up, or if you have concerns about your level, always consult a doctor. The doctor will assess your LDL cholesterol level, age, sex, family history, other risk factors, and current health status comprehensively, provide advice on appropriate target values and lifestyle improvements according to your individual risk, and discuss necessary medication if needed.
If you have a primary care physician, consult them first. If it is determined that a more specialized diagnosis or treatment is needed, you can be referred to a specialized institution such as a cardiologist or an endocrinologist specializing in diabetes and metabolism. Do not rely solely on information from the internet or self-treatment; always seek professional advice.
(Supervisor Information/Sources)
This article is intended for general information purposes only and does not endorse any specific treatment. Please consult a medical institution regarding individual health conditions and treatments.
[Summary] Managing LDL Cholesterol is an Investment in Future Health
LDL cholesterol, known as “bad,” increases the risk of serious diseases like heart disease and stroke through atherosclerosis when its levels remain high. However, high LDL cholesterol itself usually has almost no subjective symptoms. This is why it is extremely important to know your levels through regular blood tests and take appropriate measures early.
The pillars of managing high LDL cholesterol are lifestyle improvements, mainly focusing on diet therapy and exercise therapy. A balanced diet that limits saturated and trans fatty acids while actively incorporating dietary fiber and unsaturated fatty acids, along with consistent moderate aerobic exercise, can improve LDL cholesterol levels and is also expected to increase HDL (good) cholesterol. Furthermore, for smokers, quitting is essential as it dramatically increases the risk of atherosclerosis. If these lifestyle changes do not lead to the target value or if the risk is high, medication may be used under the doctor’s discretion.
Even if LDL cholesterol is lower than the reference range, it is recommended to consult a doctor if abnormally low values persist, as it may rarely indicate an underlying disease or suggested health effects.
Managing LDL cholesterol is not just about lowering numbers. It is an important “investment” to prevent future cardiovascular diseases and extend healthy lifespan. Engage with your body even when asymptomatic, and through regular testing and consultation with experts, pursue optimal health management.
コメント