Cholesterol and Triglycerides: Similarities, Differences & Relationship

Cholesterol and triglycerides are both lipids but they are not the same — they differ in their structure and composition. They do enjoy some common similar properties but, they are different in many ways. I have drawn a comparison in their blood levels, dietary restrictions, how the different types of fats affect them and some more major issues.

Cholesterol is a type of lipid while triglyceride is a type of fat. They enjoy a common relationship with quite a few similarities such as ways to lower their raised levels. But, they differ in a few ways such as their definition, structure, high-level causes, and functions.

Lipids are naturally occurring, organic compounds comprising of four main groups: fats, lipids, hormones and steroids. Fats, therefore, are a subset of lipids.

About 80% of the cholesterol is endogenously manufactured in the liver from nutrients and the rest 20% is absorbed from the dietary foods that we eat.

Whereas, triglycerides are totally acquired by the body through absorption from our dietary foods and from excess calories that we consume.

Fats and lipids have a bad reputation among the general population because their high levels can cause a heart attack or stroke. But, the fact remains that without them, neither you nor I can survive.

Having established that, a corollary to this is that both beyond their normal blood levels can be nasty to the extent of being life threatening.

Moral of the story: Keep your fatty values within their safe levels.

Similarities in triglycerides and cholesterol relationship

Some factors exist that make cholesterol and triglycerides share a common relationship.

  1. Both are essential to our body in view of their essential functions
  2. High levels of both cause complications that can be life-threatening.
  3. Both are not soluble in blood.
  4. Both are transported in the blood by lipoproteins to move freely in the blood stream.
  5. Triglycerides and LDL cholesterol both share a notorious reputation.
  6. Usually, when triglyceride levels get elevated, LDL levels are also found to be high. This can be a double whammy vis-a-vis an increased risk of heart disease and stroke. However, you may come across cases where the triglycerides are high but the cholesterol levels are normal.
  7. High levels of both triglyceride and LDL cholesterol reveal a poor cardiac health and can cause heart disease and stroke
  8. High triglycerides and cholesterol levels are treated with commonly shared drugs, which include Statins, Fibrates, and Niacin.
  9. Both are measured by a common blood lab test called the lipid profile or the lipid panel.
  10. The natural non-drug methods to lower the high levels of both consists of the same factors, namely, low-fat and low-carb diet, regular physical activity and avoiding alcohol and smoking.
  11. Both share some common causes and risk factors. They include  a familial trait,
  • foods high in saturated fats and trans fats,
  • obesity,
  • uncontrolled diabetes,
  • high alcohol intake,
  • a sedentary lifestyle,
  • certain drugs such as oral contraceptives, diuretics, beta-blockers and corticosteroids

Differences between triglycerides and cholesterol

Triglycerides and cholesterol are types of fats that do not dissolve in blood and therefore, are transported through the bloodstream with the help of proteins. Their combination with proteins is called lipoproteins.

Functions of triglycerides and those of cholesterol also differ and have been explained above. Triglycerides mainly provide the body with energy while the cholesterol help in cell wall synthesis.

About 80% of the cholesterol is produced in the liver from nutrients while only 20% is obtained from the foods that we eat. While triglycerides are obtained from the foods that we eat or from conversion from excess calories.

The chemical structure of a triglyceride [also called triacylglycerol (TAG)], consists of a long chain of one molecule of alcohol glycerol attached to up to three molecules of fatty acids through ester bonds.

Cholesterol contains steroid rings with a hydroxyl group, two methyl groups, and a hydrogen tail.

Relationship and differences between triglycerides and LDL, the bad cholesterol

Triglycerides (TG) and LDL cholesterol (the bad cholesterol), both dangerous and life-threatening when their levels are elevated, can be a double risk for heart disease and stroke. If you have a lipid profile that exhibits both these high values, you are sitting on an edge — more so if you have a family history of such events, eat foods high in saturated fats, lead a sedentary lifestyle with little physical activity, drink alcohol and smoke.

The most prominent danger is of atherosclerosis mainly contributed by high LDL levels with high TG levels playing a secondary role.

High triglyceride levels make the blood thick and sludgy. This increases the risk of clot formation, which when lodged in the heart or the brain can give you a heart attack or a stroke, each of which can cripple or kill you. Very high triglyceride levels of 500 mg/dl or more can potentially cause pancreatitis.

To worsen matters, high triglyceride levels are usually accompanied by high LDL levels, both labeled as bad fats.

According to the Centers for Disease Control and Prevention,

  • 71 million American adults, roughly 33.5% have high low-density lipoprotein (LDL) levels and of these less than half of them take treatment.
  • Again, according to the CDC, one- third of American adults have elevated levels of triglycerides.

Below is a chart depicting their normal and high levels in the blood detected through the lipid profile test.

Their high levels can be brought down without medication through natural changes, which the doctor uses as his first line of treatment. It consists of a right diet, physical exercises, and good healthy lifestyle.

Medications for high LDL cholesterol and similar drugs for high triglycerides are reserved as a last resort.

How are cholesterol and triglycerides transported through the blood?

Both cholesterol and triglycerides are not soluble in blood. But, they have to move freely in the blood stream throughout the body so that the body can avail of their benefits and functions.

Soluble proteins help transport them by binding with them and helping them move freely through the bloodstream. This combination of these fats and lipids with the proteins is called lipoproteins (lipo means relating to fat or other lipids).

Cholesterol is found in all the five lipoproteins while triglycerides are transported through the blood through VLDL only.

There are five types of lipoproteins:

  1. Chylomicrons
  2. High-density lipoproteins (HDL)
  3. Low-density  lipoproteins LDL)
  4. Very low-density lipoproteins (VLDL)
  5. Intermediate density lipoproteins( IDL)

Do read this detailed post on the lipoproteins, which includes material about their structure, composition, classification according to types and their functions.

Chart of the normal and high blood levels of cholesterol and triglycerides 

The following are the normal and high levels of cholesterol and triglycerides in mg/dL and mmol/L

Total cholesterol

  mg/dL mmol/L
Desirable Below 200 mg/dL Below 5.2 mmol/L
Borderline high 200-239 mg/dL 5.2-6.2 mmol/L
High 240 mg/dL and above Above 6.2 mmol/L

 

LDL cholesterol

  mg/dl mmol/L
Ideal for those with heart and diabetes Below 70 mg/dL Below 1.8 mmol/L
Optimal for those at risk Below 100 mg/dL Below 2.6 mmol/L
Optimal 100-129 mg/dL 2.6-3.3 mmol/L
Borderline 130-159 mg/dL 3.4-4.1 mmol/L
High 160-189 mg/dL 4.1-4.9 mmol/L
Very high 190 mg/dL and above Above 4.9 mmol/L

 

HDL

Desirable Below 40 mg/dl Below 1 mmol/L
Good 40 to 59 mg/dl 1 to 1.5 mmol/L
Very good 60 mg/dl and above Above 1.5 mmol/L

 

Triglycerides

Desirable Below 150 mg/dL

 

Below 1.7 mmol/L
Borderline 150-199 mg/dl 1.7-2.2 mmol/L
High 200-499 mg/dl 2.3-5.6 mmol/L
Too high 500 mg/dl and above Above 5.6 mmol/L

Causes that increase cholesterol and triglyceride levels

There are several causes that contribute to raising the levels of cholesterol and triglycerides.

  1. Inherited or genetic disorders of lipid metabolism
  2. Certain medical disorders such as diabetes mellitus hypothyroidism, liver and kidney disease.
  3. Regular intake of a diet high in saturated fats
  4. Sedentary lifestyle with low  physical inactivity
  5. Alcoholism
  6. Certain medications such as:
  • Older beta-blockers, that include propranolol (Inderal, Innopran XL), atenolol (Tenormin) and metoprolol (Lopressor, Toprol-XL)  increase your triglycerides
  • Estrogen, corticosteroids, oral contraceptives, and diuretics increase your cholesterol levels.

How do the different types of fats affect their levels?

  • Saturated fats raise both LDL cholesterol and triglyceride levels
  • Polyunsaturated fats are of two types: 1) Polyunsaturated fats lower LDL and also HDL (the good cholesterol) 2) Monounsaturated fats lower LDL but do not affect HDL levels.
  • Omega-3 fatty acids, which are polyunsaturated fatty acids lower triglyceride levels and increase HDL.
  • Trans fats increase LDL cholesterol and triglyceride and reduce HDL cholesterol levels.

How can you lower elevated levels of triglyceride and cholesterol?

The high levels of both cholesterol and triglycerides can be brought down substantially by

1.Eating a diet consisting of

  • low-fat and low-carb
  • plenty of fruits and vegetables
  • fiber-rich whole grains and cereals
  • no fat or low-fat milk and dairy products

2. Regular physical activity in the form of aerobic exercises

3. Avoiding alcohol and smoking

4. Maintaining optimum weight. If you are overweight or obese, lose weight.

5. As a last resort, medications

What are the symptoms of their high levels?

Elevated levels of triglycerides and cholesterol do not exhibit symptoms and are detected either accidentally through a routine blood check up or when their complications develop such as a heart attack or a stroke.

What are the main functions of cholesterol and triglycerides?

Cholesterol plays a very important role in

  • the synthesis of the cell membranes
  • production of sex hormones including estrogen, progesterone, testosterone
  • Vitamin D synthesis
  • Production of bile acids

The main functions of triglycerides are:

  • Provide energy to the body
  • Triglycerides are stored in the adipose tissue under the skin and around the body organs and occasionally in muscle cells. They provide insulation and a protective cover to the organs.
  • Along with the phospholipids, they form the lipid bilayers of the cell membranes
  • Provide nutrition by helping in the absorption of fat-soluble vitamins.

What are the dangers of their high levels?

High LDL cholesterol cause atheromatous plaques to build up on the arterial walls. This narrows the lumen of the arteries and reduces blood supply to the organ or part of the body distal to the plaque.

In case blood supply to the heart is reduced, you can develop angina or a heart attack.

The complications of high cholesterol include:

  • Heart attack
  • Stroke
  • Peripheral artery disease. (PAD)
  • High blood pressure.
  • Kidney disease if plaques build up in the renal arteries

High triglyceride levels make the blood thick and sludgy increasing the risk of developing blood clots. The dangers of high triglycerides include:

  • Metabolic syndrome – a cluster of conditions, which include diabetes, hypertension, high triglyceride levels and a large waist circumference
  • Pancreatitis with very high levels
  • Heart attack
  • Stroke
  • Peripheral artery disease (PAD)

 

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