Understanding Cholesterol and the Lipid Profile

Cholesterol has a poor reputation, which is a little unfair. It is a substance your body needs — it forms part of every cell membrane and is a building block for several hormones and for vitamin D. Your liver makes most of what you carry.

The clinically important question is not whether you have cholesterol, but how much of it is circulating, in which forms, and what that means alongside the rest of your risk profile.

Why this matters

Abnormal blood lipids are one of the established contributors to atherosclerosis — the gradual narrowing and stiffening of arteries that underlies most heart attacks and many strokes. Like raised blood pressure, it produces no symptoms while it develops, so it is found by testing rather than by feeling unwell.

What medical guidance says

What the report shows

Cholesterol does not dissolve in blood, so it travels wrapped in particles called lipoproteins. A lipid profile reports these fractions rather than one figure:

• LDL cholesterol — often called the harmful fraction, because LDL particles deposit cholesterol into artery walls. It is usually the main focus of treatment decisions.
• HDL cholesterol — often called the protective fraction, as HDL carries cholesterol back towards the liver. Very low HDL is generally unfavourable.
• Triglycerides — a different type of blood fat, strongly influenced by recent diet, alcohol, body weight and blood sugar control.
• Total cholesterol — the overall figure. On its own it is the least informative number on the report, because it does not distinguish between the fractions.
• Non-HDL cholesterol — total minus HDL, which some clinicians favour because it captures all the potentially harmful particles together.

Why the pattern matters more than one number

Two people can have identical total cholesterol and quite different cardiovascular risk, because the split between the fractions differs. This is why a doctor reads the profile as a set.

Lipids are also only one input. Decisions about whether a level needs treatment take into account age, blood pressure, smoking, diabetes, family history, kidney function and whether you have existing heart disease. The same LDL value can be entirely acceptable in one person and warrant treatment in another. That judgement belongs to your doctor.

What influences your levels

Some factors can be influenced and some cannot. Genetics play a real part — familial hypercholesterolaemia, an inherited condition, causes markedly raised LDL from a young age regardless of diet, which is one reason family history is worth mentioning to your doctor.

• Dietary pattern, particularly the amount of fried food, refined carbohydrate and sugar rather than any single ingredient.
• Body weight, especially weight around the abdomen.
• Physical activity, which tends to raise HDL and lower triglycerides.
• Alcohol, which raises triglycerides notably.
• Smoking, which lowers HDL alongside its other effects.
• Poorly controlled diabetes and untreated thyroid disorders.

Everyday dietary measures

These are general wellbeing measures. They do not replace lipid-lowering medicine where one has been prescribed.

• Favour whole grains, millets, pulses, vegetables and fruit as the base of most meals.
• Include sources of soluble fibre such as oats, barley, beans and pulses regularly.
• Use nuts and seeds in modest quantities in place of fried snacks.
• Reduce deep-fried food and never reuse frying oil repeatedly.
• Limit sugar-sweetened drinks and packaged juices, which raise triglycerides.
• Moderate alcohol, which has a particularly direct effect on triglycerides.

About the test itself

Fasting for around nine to twelve hours has traditionally been requested, mainly because triglycerides rise after eating. Many laboratories and clinicians now accept non-fasting samples for routine assessment. Follow the instruction your doctor or laboratory gives you rather than assuming, and mention any recent illness, since acute illness can temporarily shift lipid values.

A doctor assessing lipids will often also look at blood sugar, thyroid function and kidney function, because those conditions influence lipids and change what a result means.

Related reading: Understanding blood pressure readings

When to consult a doctor

Review any lipid report with the doctor who ordered it. Mention a family history of early heart attack or stroke, or of very high cholesterol, as it changes how a result is interpreted.

Seek emergency care immediately for chest pain, pressure or tightness, pain spreading to the arm, neck or jaw, sudden severe breathlessness, or sudden weakness, numbness or difficulty speaking. Do not wait to arrange a test.

Never stop a prescribed cholesterol medicine because your report has improved — the improvement is frequently the medicine at work. Raise side effects such as unusual muscle pain with your doctor rather than stopping on your own.