Cholesterol – A guide to help you understand

Cholesterol – A guide to help you understand

What is cholesterol?

Cholesterol is a fatty substance found in your blood. It’s a type of lipid produced by animal cells as part of the cell membrane. Cholesterol is also used to make hormones, nerve sheaths, bile salts and vitamin D. It is also used to transport proteins. It is typically produced in the liver. It is essential for bodily functions.

Cholesterol ingested in foods have very little effect on our total cholesterol because our body automatically regulates cholesterol production as our intake goes up or down.

Why all the controversy?

Cholesterol has endured a bad reputation throughout the years. According to the lipid hypothesis, it is postulated that high cholesterol can increase the risk of cardiovascular disease and that the cholesterol in your blood can build up in walls of blood vessels, causing blockages that lead to heart attacks and strokes. It is also a postulated theory that eating more saturated fat will increase cholesterol (especially LDL) and hence increase the risk of heart disease. However, more recent studies have shown these theories to be false.

Different types of cholesterol

Most people understand there’s different types of cholesterol. HDL (high density lipoprotein) is traditionally labelled as the good cholesterol. LDL (low density lipoprotein) is traditionally labelled as the bad cholesterol. There is also triglycerides, which is a form of fatty substance in the blood.

However, it turns out that LDL is not all bad. There are actually different types of subtypes of LDL particles, which are classified according size, with seven subfractions. The larger, fluffier types of LDLs are actually harmless, however these can ‘oxidise’, forming small dense LDL particles – and it is these ones which are associated with higher risk of cardiovascular disease.

How the large fluffy LDL becomes ‘oxidised’ to become small dense LDLs is thought to be by sugars and polyunsaturated fats, like vegetable oils. Other things that can oxidise LDLs include stress, pollutants, alcohol, pesticides, toxins and lack of exercise.

In blood tests, a standard cholesterol profile does not usually measure the sizes of LDL particles. It is possible to request a special test called ‘LDL subfractions’ to characterise the sizes of LDL particles. This special test does not attract medicare rebate and takes a longer duration for results to be yielded.

We also now understand triglyceride levels are a better test for assessing the risk of cardiovascular disease. Triglycerides are usually elevated in overweight or obese people and can be reduced by cutting down sugar and carbohydrate intake. Triglycerides in your blood are made in the liver from excess sugars that have not been used for energy, in particular foods containing carbohydrates, for example sugars and flour. In blood tests, ideally, levels lower than 1 would be recommended.

We also understand that a high HDL level is protective of cardiovascular disease. Ideally the level higher than 1 would offer protection.

Instead of traditionally looking at the total cholesterol and LDL level, current research now tells us that a better way to assess cardiovascular risk is the triglyceride and HDL levels. It is also helpful to calculate the triglyceride to HDL ratio.

Triglyceride: HDL ratio < 1 is good, > 1.8 is bad.

What about cholesterol lowering drugs?

Doctors often prescribe statins for people to lower their cholesterol in hope to reduce risk of cardiovascular disease. It certainly has its place, especially in those people who are already showing evidence of established cardiovascular disease. Statins successfully help lower the LDL. They also help stabilise the blood vessel lining. However, risks should be balanced against benefits. The risk should be provided to the individual and balanced with other cardiovascular risk factors, for example insulin resistance or metabolic syndrome, as well as any evidence of existing heart disease.

What are statin side effects?

  • Muscle aches and pains
  • Liver damage
  • Increase risk of type 2 diabetes
  • Neurological side effects, including memory loss and Alzheimer’s disease

Coronary Artery Calcium (CAC) score

This is a test that involves a CT scan, which can measure calcium deposits (plaques) that indicates heart disease. A score is generated with this test and determine if you are at high risk or low risk of heart attack. Unfortunately, at the time of writing, there is no Medicare rebate for this test. A local imaging provider near my practice charges $220 for this test.

In Summary

  • Cholesterol plays an important role in normal bodily function.
  • The most important marker in the cholesterol profile is your HDL and triglyceride.
  • The evidence for high cholesterol and heart disease is controversial.
  • Lowering cholesterol may not be necessary.
  • Eating real foods and less carbohydrates, can increase your HDL and reduce triglyceride.
  • It is important to take into account of the whole individual including other cardiovascular risk factors into consideration.


This article does not provide treatment or individualised advice. Please discuss with your doctor about your change in lifestyle especially those who take regular medications or have medical conditions.

I am Dr Avi Charlton. I am a General Practitioner with a special interest in nutrition. I have done training with Nutrition Network and Low Carb Down Under.
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This post was originally written for my old website You can still visit. It was written on 4th March 2022.