A level-readyAll subjects · Biology · WBI11 (Unit 1)
CVD risk factors, antioxidants and cholesterol
Some risks of cardiovascular disease are fixed, others we can change. Diet affects blood cholesterol and the antioxidants we take in.
Risk factors
A risk factor increases the chance of a disease; it does not guarantee it.
- Cannot be changed: genetics (family history), age (risk rises), sex (men tend to develop CVD earlier).
- Can be changed: high blood pressure, smoking (chemicals damage the endothelium; carbon monoxide reduces oxygen carried), inactivity, and diet (high saturated fat, high salt, too much energy leading to obesity).
Risk factors interact: someone who smokes and has high blood pressure has a much higher risk than either alone.
Cholesterol, LDL and HDL
Cholesterol is carried in lipoproteins.
- LDL (low-density lipoprotein) carries cholesterol from the liver to tissues. High LDL is linked to cholesterol being deposited in artery walls, so it raises CVD risk. Diets high in saturated fat tend to raise LDL.
- HDL (high-density lipoprotein) carries excess cholesterol from tissues back to the liver. High HDL is linked to lower risk.
Evidence for a causal link comes from large studies showing a consistent dose-response relationship, plus a mechanism (cholesterol in plaques) and trials where lowering LDL (for example with statins) reduces heart attacks.
Antioxidants
Free radicals are reactive molecules that can damage cells, including the artery endothelium. Antioxidants, such as vitamin C (fruit and vegetables), vitamin E and plant flavonoids, react with free radicals and make them harmless.
Studies show people with diets rich in fruit and vegetables have lower CVD risk, but trials of antioxidant supplements have given conflicting results, so the link is not proven to be causal.
Worked example
A patient has high LDL and low HDL. Explain why this increases CVD risk.
- High LDL means more cholesterol carried to tissues, where it can be deposited in damaged artery walls.
- Low HDL means less excess cholesterol is removed to the liver.
- So plaques are more likely to form.
Answer: More cholesterol is deposited in artery walls and less is removed, so atherosclerosis is more likely.
Check yourself
- Which CVD risk factor cannot be changed?
- Smoking
- Age
- Blood pressure
- Physical inactivity
Show answer
Age. Age rises whatever we do; the others can be changed by lifestyle or treatment.
- What does LDL do?
- Carries excess cholesterol back to the liver
- Breaks down fibrin clots
- Carries oxygen to the heart
- Carries cholesterol from the liver to body tissues
Show answer
Carries cholesterol from the liver to body tissues. LDL delivers cholesterol to tissues; high levels are linked to plaque formation.
- Which blood lipid profile carries the lowest CVD risk?
- High LDL and low HDL
- Low LDL and high HDL
- High LDL and high triglycerides
- Low HDL and low LDL with obesity
Show answer
Low LDL and high HDL. Low LDL means less deposition; high HDL means more removal.
- How do antioxidants such as vitamin C reduce damage to arteries?
- They dissolve existing plaques
- They raise blood pressure
- They neutralise free radicals that could damage the endothelium
- They increase blood clotting
Show answer
They neutralise free radicals that could damage the endothelium. Antioxidants react with free radicals, preventing cell damage.
- Which is a way smoking increases CVD risk?
- Chemicals in smoke damage the artery endothelium
- Nicotine lowers blood pressure
- Carbon monoxide increases oxygen carried by haemoglobin
- Smoke raises HDL levels
Show answer
Chemicals in smoke damage the artery endothelium. Endothelial damage starts atherosclerosis; CO also reduces oxygen carrying.
- Which evidence best supports a causal link between high LDL and CVD?
- A single study of 20 people
- People with CVD often eat breakfast
- Trials in which lowering LDL reduces the number of heart attacks
- LDL is found in the blood of all people
Show answer
Trials in which lowering LDL reduces the number of heart attacks. An intervention that lowers LDL and reduces disease, with a known mechanism, supports causation.
Sources
Last updated 7 November 2026. Spotted a mistake? Tell us.