Know Your Numbers: Cholesterol — Understanding the Different Lipids
What is Cholesterol?
Cholesterol is a fatty substance essential for life. It helps build cell membranes, produce hormones (like oestrogen and testosterone), and make vitamin D. The liver makes most of the cholesterol in our bodies, but it also comes from food. Too much “bad” cholesterol can lead to a buildup of fatty plaques in arteries, which can lead to heart disease and stroke. The good news is that small changes can make a big impact when it comes to managing cholesterol.
Checking your lipid profile with a blood test provides valuable insights into your cardiovascular health. In this article, we’ll explain the different types of cholesterol and what your numbers really mean.
1. Total Cholesterol
This is the sum of all the cholesterol in your blood (LDL, HDL, and other fractions). While useful as a broad measure, it doesn’t show the balance between “good” and “bad” cholesterol. That’s why looking at the whole lipid profile is important.
Target levels:
5.0 mmol/L or less for most adults (Irish Heart Foundation, Heart UK).
4..5 mmol/L or less if you already have heart disease or diabetes.
2. LDL Cholesterol (“Bad Cholesterol”)
Low-Density Lipoprotein (LDL) carries cholesterol from the liver to cells. When LDL levels are too high, cholesterol gets deposited in artery walls, forming plaques. These plaques can narrow arteries or rupture, causing heart attack or stroke. Studies consistently show that lowering LDL reduces the risk of cardiovascular events, even at already low levels (Ference et al., JAMA, 2017).
Target levels:
3.0 mmol/L or less for most adults.
1.8–2.0 mmol/L or less for those with established cardiovascular disease.
3. HDL Cholesterol (“Good Cholesterol”)
High-Density Lipoprotein (HDL) helps carry cholesterol away from the arteries back to the liver, where it can be broken down or removed. While low HDL is linked with risk, artificially raising HDL (via supplements or drugs) hasn’t consistently reduced heart disease. Lifestyle changes—like exercise, smoking cessation, and healthy fats—remain the best way to support healthy HDL.
Target levels:
1.0 mmol/L or higher for men.
1.2 mmol/L or higher for women.
4. Non-HDL Cholesterol
This ia a measure that includes all “bad” cholesterol particles (LDL, VLDL, IDL, lipoprotein(a)) but excludes HDL. Clinical guidlines now recommend non-HDL cholesterol as a key marker because it’s a better predictor of cardiovascular risk than LDL alone.
Target levels:
Less than 4.0 mmol/L for healthy adults.
Less than 2.6 mmol/L for those with heart disease or high risk.
5. Triglycerides
Triglycerides are a type of fat in your blood, mainly from excess calories (particularly sugar, alcohol, and refined carbs) converted into storage fat. High triglycerides can increase risk of heart disease and are strongly linked with conditions like type 2 diabetes, obesity, and metabolic syndrome. Elevated triglycerides plus low HDL often signal insulin resistance—a strong risk factor for both cardiovascular disease and NAFLD (non-alcoholic fatty liver disease).
Target levels:
2.0 mmol/L or less for adult men and women
How to Optimise Your Lipid Profile
The good news is that lifestyle changes can improve nearly every part of the lipid panel:
Lower LDL & non-HDL cholesterol:
Swap saturated fats (butter, fatty cuts of meat) for unsaturated oils (olive, rapeseed).
Add soluble fibre (oats, pulses, barley).
Plant sterols (in fortified foods) can also help
Increase HDL cholesterol:
Regular physical activity.
Quit smoking.
Include healthy fats from nuts, seeds, and oily fish.
Reduce triglycerides:
Cut down on sugar and alcohol.
Prioritise wholegrain carbs and protein at meals.
References
Irish Heart Foundation. Cholesterol – how to keep your heart healthy. irishheart.ie
NICE. Cardiovascular disease: risk assessment and reduction, including lipid modification. NG238, 2023. nice.org.uk
Heart UK. Understanding your cholesterol test results. heartuk.org.uk
Ference BA et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. JAMA. 2017;316(12):1289–97.
Reiner Ž. Hypertriglyceridaemia and risk of coronary artery disease. Nat Rev Cardiol. 2017.
