Evidence linking cholesterol and CVDSpec 1.18(ii)
In short
Several lines of evidence support a causal relationship between blood cholesterol (total and LDL) and cardiovascular disease. Population studies show higher rates of CVD where blood LDL is high, people with inherited very high cholesterol develop CVD early, LDL is found in plaques, and trials show that lowering LDL reduces heart attacks and strokes.
- Correlation in large population studies: groups with higher total and LDL cholesterol have more cardiovascular disease.
- Genetic evidence: people with inherited conditions that cause very high LDL cholesterol develop atherosclerosis and CVD at a young age.
- Mechanism: LDL cholesterol is found in plaques; oxidised LDL is taken up by macrophages to form foam cells.
- Intervention trials: lowering LDL cholesterol with statins and diet reduces the number of heart attacks and strokes.
- Laboratory studies: animals fed high-cholesterol diets develop atherosclerosis.
Not every piece of evidence is consistent. Some people with normal cholesterol develop CVD and some people with high cholesterol do not, because CVD has many risk factors. Studies of drugs that raise HDL have not always shown reduced CVD. Overall the weight of evidence from several different kinds of study supports a causal role for high LDL.
Strong answers use more than one type of evidence (population, genetic, mechanism, intervention) and mention that CVD is multifactorial, which is why correlation alone is not proof.
Written and checked against the Edexcel International A Level Biology (YBI11) specification · Updated October 2026