People seem to have a negative perception of cholesterol. However, the waxy substance is only unhealthy when it is present in too high quantities in the body. In truth, cholesterol is actually an essential substance that is critical to the body’s ability to divide cells and make vitamins, and also aids in the production of some hormones.
That being said, it’s important to keep your cholesterol in check because high cholesterol levels increase your risk of heart disease and stroke.
Where cholesterol comes from and what is it good for
Our body accesses cholesterol from two sources. One is internal, as the liver makes its own cholesterol — this is the main source of cholesterol in your blood. The other is external, from the various animal-sourced foods, such as meat, poultry, eggs, and dairy products — this is known as dietary cholesterol.
Cholesterol is oil-based, so it does not mix with the blood, which is water-based. Instead, it travels around the body transported in lipoproteins, in order to serve four basic functions:
strengthening the structure of cell walls;
making up digestive bile acids in the intestine;
priming the body to produce vitamin D;
contributing to the production of certain hormones.
There are also two main types of lipoproteins:
low-density lipoproteins (LDL), popularly known as “bad” cholesterol because LDL dumps the cholesterol into your arteries.
high-density lipoproteins (HDL), also known as “good” cholesterol because it removes cholesterol from your arteries by carrying it back to the liver.
Why too much cholesterol can be unhealthy and dangerous
Cholesterol combines with other substances found in the blood to form a thick, hard deposit on the inner walls of the arteries. The more cholesterol found in your blood, the higher the risk of cardiovascular diseases. For instance, too much cholesterol can naturally narrow the arteries and make them less flexible, causing a condition known as atherosclerosis in which blood flow is restricted. Sometimes, too much cholesterol can form blood clots, clogging the arteries, and thereby triggering a heart attack or stroke.
How do I know if I have high cholesterol?
In order to determine whether you have high levels of cholesterol, you’ll have to take a blood test that measures both HDL and LDL levels. The doctor will then examine these readings, along with other risk factors of heart disease or stroke, such as high blood pressure, obesity, type 2 diabetes, triglycerides, and smoking, in order to determine whether you have too much cholesterol.
Generally, the guidelines below can help inform you whether or not your cholesterol is too high.
Total cholesterol (U.S.)
Total cholesterol (Canada and most of Europe)
Below 200 mg/dL
Below 5.2 mmol/L
240 mg/dL and above
Above 6.2 mmol/L
LDL cholesterol (U.S. and some other countries)
LDL cholesterol* (Canada and most of Europe)
Below 70 mg/dL
Below 1.8 mmol/L
Best for people who have heart disease or diabetes.
Below 100 mg/dL
Below 2.6 mmol/L
Optimal for people at risk of heart disease.
Near optimal if there is no heart disease. High if there is heart disease.
Borderline high if there is no heart disease. High if there is heart disease.
High if there is no heart disease. Very high if there is heart disease.
190 mg/dL and above
Above 4.9 mmol/L
*Canadian and European guidelines differ slightly from U.S. guidelines. These conversions are based on U.S. guidelines.
HDL cholesterol (U.S.)
HDL cholesterol(Canada and most of Europe)
Below 40 mg/dL, men Below 50 mg/dL, women
Below 1 mmol/LBelow 1.3 mmol/L
40-59 mg/dL, men 50-59 mg.dL, women
1-1.5 mmol/L1.3-1.5 mmol/L
60 mg/dL and above
Above 1.5 mmol/L
Triglycerides (Canada and most of Europe)
Below 150 mg/dL
Below 1.7 mmol/L
500 mg/dL and above
Above 5.6 mmol/L
What causes high cholesterol
Sedentarism, obesity, and an unhealthy diet all contribute to high LDL cholesterol and low levels of HDL cholesterol. The main risk factors for high levels of cholesterol are:
A poor diet consisting of too much saturated and trans fats.
Obesity. Having a body mass index (BMI) over 30 statistically puts you at a greater risk of high cholesterol than the general population.
Lack of exercise. Rigorous, frequent physical activity can boost the body’s HDL (good cholesterol) while increasing the size of LDL particles (bad cholesterol), which makes it less harmful.
Smoking. Nicotine damages and constricts the walls of blood vessels, making them more prone to the accumulation of fatty deposits.
Age. As we age, the liver becomes less capable of removing LDL cholesterol.
Diabetes. People with diabetes have high blood sugar, which puts them at risk of producing a dangerous type of cholesterol called very-low-density lipoprotein (VLDL) while also lowering HDL cholesterol.
Genetics. Some people inherit genes from their parents that can cause them to be susceptible to high cholesterol levels in their blood — it’s called familial hypercholesterolemia.
How to lower cholesterol
If you have high cholesterol, the first thing you must address is diet. This is why it’s important to:
Limit the amount of animal fats and use good fats in moderation
Eat a balanced diet that emphasizes fruits, vegetables, and whole grains
Additionally, the following will help lower your cholesterol:
Exercise regularly and maintain a healthy weight;
Drink alcohol only in moderation, if at all;
The above recommendations can also help prevent you from having high cholesterol in the first place.
If a patient has made significant lifestyle changes but bad cholesterol and triglyceride levels remain high, your doctor may recommend medication. These may include statins (drugs that effectively prevent the liver from making as much cholesterol), bile-acid-binding resins, cholesterol absorption inhibitors, and injectable medications such as PSCK9 inhibitors. Additionally, those with high triglyceride levels may benefit from medication such as fibrates, niacin, and omega-3 fatty acid supplements.
Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space. In his spare time, Tibi likes to make weird music on his computer and groom felines.