Cholesterol Tests: Understanding What Your Results Mean

A complete cholesterol test—also called a lipid panel or lipid profile—is a blood test that measures the amount of cholesterol and triglycerides in the blood to assess your heart health and estimate your risk of cardiovascular disease. [1]

If cholesterol levels get too high, it can lead to a buildup of fatty deposits—often referred to as plaques—in arteries that, in turn, increase the risk of age-related conditions like heart attacks, stroke, and heart disease. There are typically no signs or symptoms associated with high cholesterol, and the only way to determine your cholesterol levels is through a complete cholesterol test. [1] While there is a genetic component to cholesterol levels, cholesterol is highly influenced by lifestyle choices. Knowing your cholesterol levels, how to interpret the results, and what those results mean in the context of your lifestyle, provide the insights needed to take control of and optimize your health. 

Let’s dive into cholesterol testing, the biomarkers this test measures, and how to understand your test results.  



What blood biomarkers do cholesterol tests measure?

Cholesterol is a waxy, fat-like substance that the body uses to build cells and make vitamins and hormones. The body internally synthesizes the cholesterol it needs and you can also ingest cholesterol from foods, mainly animal products. Cholesterol travels through the bloodstream in small units called lipoproteins, which are made out of both fat and protein. [2]

Complete cholesterol tests also measures these lipoproteins and the levels of lipids, or fats, in your blood.

A standard lipid panel includes: 

• Low-density lipoprotein (LDL) is a potentially harmful type of cholesterol if it builds up in the arteries. This can lead to blood vessel damage, restricted blood flow, and blockages, which increases the risk of heart attacks, strokes, and heart disease. LDL is commonly referred to as “bad cholesterol.” 
• High-density lipoprotein (HDL), also known as the “good cholesterol,” is a protective form of cholesterol that helps to remove LDL cholesterol from circulation and brings it back to the liver, where it is processed and removed. 
• Triglycerides are a form of fat that circulates in the bloodstream. The combination of high levels of triglycerides with high LDL cholesterol and low HDL cholesterol can increase your risk for heart attack and stroke.
• Total cholesterol is a measure of the total amount of cholesterol in your blood. It includes LDL cholesterol, HDL cholesterol, and a fraction of triglyceride levels. 

Some lipid panels may include additional measurements:

• Very low-density lipoprotein (VLDL) is the precursor to LDL and IDL (intermediate-density lipoprotein). It is another type of cholesterol linked to an increased risk of cardiovascular disease but is not used to determine treatment for elevated cholesterol. [1,2]
• Apolipoprotein B (ApoB) is a protein found on the surface of harmful lipoproteins including VLDL, LDL, and IDL. ApoB has emerged as an essential marker for assessing cardiovascular disease risk when compared to LDL, non-HDL, and LDL-p. [3]
• Lipoprotein (a) is a specific type of LDL with properties that make it more likely to cause blockages and blood clots in the arteries. High levels of lipoprotein (a) may mean a high risk for cardiovascular disease, stroke, and heart attacks, even if your other cholesterol levels are healthy. Therefore, this additional measurement can provide a more accurate depiction of heart disease risk when included along with a standard lipid panel. [4]

What can cholesterol test results tell you about your health and longevity?

Cholesterol test results are a key indicator of heart health and longevity. These results reveal a person’s risk of heart attack, stroke, and cardiovascular disease, ultimately impacting overall health and lifespan. Numerous studies draw a clear link between high total cholesterol, LDL cholesterol, and triglycerides with increased heart disease and mortality risk. For example, researchers investigated the long-term effects of cholesterol levels by analyzing data collected over 35 years. They found that elevated total cholesterol and LDL levels and low HDL levels increased the risk of cardiovascular disease and premature death more than two-fold when compared to those with optimal levels. [5] 

Similarly, another study combined the results of three different cohorts, totaling over 80,000 men, and discovered that high total cholesterol levels increased cardiovascular mortality risk more than two-fold and all-cause mortality by 30-50 percent. On the other hand, men with favorable cholesterol levels had an estimated greater life expectancy of 3.8-8.7 years. [6]

What do normal cholesterol levels mean? 

The following are considered normal, healthy ranges for cholesterol and triglycerides:



What are optimal cholesterol levels for health?

Normal cholesterol levels are not necessarily optimal. From a clinical perspective, a doctor would consider the presence of other cardiovascular risk factors including blood pressure, smoking history, diabetes, and family history of heart disease. From there, they would determine an optimal target for your cholesterol levels. For example, normal LDL levels are under 100 mg/dL, but for those with diabetes or who already have heart disease, optimal LDL cholesterol levels are considered below 70 mg/dL. [7]

InsideTracker’s personalized health analysis also provides optimal zones for cholesterol biomarkers for those looking to fine-tune their health. These optimal zones account for sex, ethnicity, activity level, and age.

What do high cholesterol levels indicate? 

High total cholesterol, LDL cholesterol, and triglyceride levels paired with low HDL are considered risk factors for cardiovascular complications. The following are considered borderline and high lipid panel levels:

Total cholesterol:

• Borderline high: 200-239 mg/dL
• High = ≥ 240 mg/dL

LDL cholesterol: 

• Borderline high: 100-159 mg/dL
• High = ≥ 160 mg/dL

Triglycerides: 

• Borderline high = 150-199 mg/dL
• High ≥ 200 mg/dL

ApoB: 

• Borderline high = 90-119 mg/dL
• High = ≥120 mg/dL

How can you lower high cholesterol?

There are several natural ways to help lower high cholesterol and triglycerides. These include:

• Reduce intake of high-saturated fat foods (like red and processed meat)
• Incorporate more sources of unsaturated fats (avocados, olive oil, nuts, seeds, fish)
• Eat fiber-rich foods (oats, chia seeds, fruits, vegetables, and legumes)
• Consider targeted supplementation (garlic, alpha-lipoic acid, plant sterols)

It’s important for physicians or healthcare providers to monitor high cholesterol and other cardiovascular risk factors to determine if medication in addition to lifestyle adjustments is warranted to achieve optimal cholesterol.

Can HDL levels be too high?

Unlike total cholesterol, LDL, triglycerides, and ApoB, which should be below a certain threshold to support optimal heart health, HDL levels should be above a given threshold as they are cardioprotective. 

But on occasion, HDL levels can also be too elevated and are associated with increased risk for both infectious and chronic diseases. Genetics, some medications, and a high saturated fat diet are all factors that can drive HDL levels above optimal. Since the documentation that elevated levels of the good-cholesterol may be detrimental to health is relatively new, few studies have looked at interventions to effectively and healthfully, lower HDL levels. If your HDL is flagged as elevated, it’s best to monitor it with your physician. [8]

HDL cholesterol:

• High: >200 mg/dL
• Low = <46 mg/dL

Can cholesterol levels be too low?

Since HDL is cardioprotective, levels of this biomarker can be too low. For other types of cholesterol, it is evident that lower levels can lower the risk of cardiovascular disease, but whether it is possible to lower some cholesterol levels too much has been controversial.

HDL cholesterol

Low HDL cholesterol levels—which can result from lifestyle factors such as insufficient physical activity, diets high in saturated fats, excess weight, and smoking—are associated with an increased risk of heart disease and premature death related to both cardiovascular and noncardiovascular causes. [9,10] HDL is considered cardioprotective because these particles remove LDL cholesterol from the blood and fight inflammation and oxidative damage. [10]

However, recent findings from genetic studies and clinical trials of drugs that specifically raise HDL cholesterol have not been shown to improve cardiovascular outcomes. [11] Scientists agree that more research on the relationship between low HDL cholesterol and heart disease is still needed.

Total cholesterol

Total cholesterol levels outside of the normal reference range, including both high and low values, may have negative health effects. In a cohort study of over 25,000 U.S. adults, researchers found that the lowest and highest total cholesterol levels were correlated with an increased risk of death from cancer, cardiovascular disease, and all causes. [12]

LDL cholesterol

While initial studies raised concerns that lowering LDL cholesterol too far might interfere with normal cellular functions, the latest research suggests this is not the case. [13] In a recent meta-analysis published in JAMA Cardiology, there was no increased risk of adverse outcomes including muscle aches, liver dysfunction, new-onset diabetes, cancer, and bleeding strokes—even when LDL was lowered to as low as 20 mg/dL. [14]

Triglycerides

There currently is no lower limit for triglyceride levels and having low triglycerides is not associated with any health risks. [15] However, extremely low levels (less than 40 mg/dL), may indicate a medical condition or disease, such as malnutrition or hyperthyroidism. 

Who should get a cholesterol test? 

All adults should get their cholesterol levels checked regularly, especially those who are undergoing treatment for high cholesterol or who have a risk factor for high cholesterol. [7] 

Risk factors for high cholesterol include: [7] 

• Family history of high cholesterol or heart disease
• History of heart attack or stroke
• Age > 65
• Diabetes
• Kidney disease
• Cigarette use
• Excessive alcohol intake
• Elevated BMI
• Sedentary lifestyle
• Dietary patterns high in saturated fat and low in soluble fiber

How often should you get your cholesterol levels checked? 

Current guidelines recommend children, adolescents, and young adults should have their cholesterol levels checked once between the ages of 9 and 11 and again between 17, and recommend most adults get their levels checked as follows [7]

Males 

• Ages 21-45: Every 4-6 years
• Ages 45-65: Every 1-2 years
• Ages 65+: Annually 

Females

• Ages 21-45: Every 4-6 years
• Ages 55-65: Every 1-2 years
• Ages 65+: Annually 

However, it takes about three months to significantly influence blood cholesterol levels through diet and lifestyle, so only testing once every handful of years doesn’t allow you to track how your lifestyle or the healthy changes you make are impacting your blood cholesterol. To truly optimize your health, InsideTracker scientists encourage routine blood testing every three to six months to proactively monitor your blood cholesterol and see the real-time changes in your lifestyle on objective indicators of health. 

Do you need to fast before a cholesterol blood test? 

It is typically recommended to fast before a cholesterol test, as triglyceride levels may remain elevated for several hours after eating, which can also impact LDL levels if it is calculated using the triglyceride level. [15] 

Avoid eating or drinking (except for water or black coffee) for the 12 hours leading to your blood test. 

Key takeaways

A cholesterol test is a blood test that measures the level of fats in your blood. High total cholesterol, LDL cholesterol, and triglycerides and low HDL cholesterol are associated with an increased risk for heart attack, stroke, and heart disease. Regular cholesterol testing is vital for understanding your cardiovascular disease risk while serving as an important metric of overall health and longevity. 

Many people’s medical insurance does cover yearly cholesterol testing, but not all doctors order yearly bloodwork for seemingly healthy adults. At preventative appointments always ask what bloodwork is covered by your insurance, and know that there are options to get bloodwork done regularly without insurance at labs or at home through solutions like InsideTracker.

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References:

[1] https://pubmed.ncbi.nlm.nih.gov/31194434/ 

[2] https://pubmed.ncbi.nlm.nih.gov/26247089/ 

[3] https://pubmed.ncbi.nlm.nih.gov/34773457/ 

[4] https://pubmed.ncbi.nlm.nih.gov/27074913/ 

[5] https://pubmed.ncbi.nlm.nih.gov/31137992/ 

[6] https://pubmed.ncbi.nlm.nih.gov/10891962/ 

[7] https://pubmed.ncbi.nlm.nih.gov/30586774/ 

[8] https://pubmed.ncbi.nlm.nih.gov/29228167/

[9] https://pubmed.ncbi.nlm.nih.gov/29326314/

[10] https://pubmed.ncbi.nlm.nih.gov/27810046/

[11] https://pubmed.ncbi.nlm.nih.gov/25131981/ 

[12] https://pubmed.ncbi.nlm.nih.gov/33691735/

[13] https://pubmed.ncbi.nlm.nih.gov/28295777/

[14]  https://pubmed.ncbi.nlm.nih.gov/30073316/

[15] https://pubmed.ncbi.nlm.nih.gov/24436475/