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This lesson covers the relationship between diet and cardiovascular disease (CVD) and high blood pressure (hypertension), as required by AQA GCSE Food Preparation and Nutrition specification 8585, section 3.2.3. You must understand the dietary factors that contribute to cardiovascular disease, how high blood pressure develops, and what dietary changes can reduce the risk.
The cardiovascular system consists of the heart, blood, and blood vessels (arteries, veins, and capillaries). Its function is to transport oxygen, nutrients, hormones, and waste products around the body.
Cardiovascular disease (CVD) is a general term for conditions affecting the heart and blood vessels. It is the leading cause of death in the UK, responsible for approximately 25% of all deaths. The main types of CVD are:
| Condition | Description |
|---|---|
| Coronary heart disease (CHD) | The coronary arteries (which supply blood to the heart muscle) become narrowed or blocked by a build-up of fatty deposits (atherosclerosis), reducing blood flow to the heart |
| Heart attack (myocardial infarction) | A complete blockage of a coronary artery, cutting off blood supply to part of the heart muscle, which can die |
| Stroke | A blood vessel in the brain becomes blocked or bursts, cutting off blood supply to part of the brain |
| Peripheral arterial disease | Narrowing of arteries that supply blood to the limbs (usually legs) |
Atherosclerosis is the build-up of fatty deposits (called plaques or atheromas) on the inner walls of arteries. This is the underlying cause of most cardiovascular disease.
graph LR
A["Healthy Artery<br/>(wide, clear lumen)"] --> B["Early Atherosclerosis<br/>(fatty streak on artery wall)"]
B --> C["Advanced Atherosclerosis<br/>(plaque narrows the lumen)"]
C --> D["Blood Clot (Thrombosis)<br/>(blocks the artery completely)"]
D --> E["Heart Attack<br/>(if coronary artery)<br/>or Stroke<br/>(if brain artery)"]
style A fill:#27ae60,color:#fff
style B fill:#f39c12,color:#fff
style C fill:#e67e22,color:#fff
style D fill:#e74c3c,color:#fff
style E fill:#c0392b,color:#fff
The process:
| Dietary Factor | How It Increases CVD Risk |
|---|---|
| High saturated fat intake | Raises blood LDL cholesterol ("bad" cholesterol), which deposits fat in artery walls, promoting atherosclerosis |
| High trans fat intake | Raises LDL cholesterol and lowers HDL cholesterol ("good" cholesterol). Found in some processed and fried foods, hydrogenated vegetable oils |
| High salt (sodium) intake | Raises blood pressure (see below), which damages artery walls and increases the risk of heart attack and stroke |
| High free sugar intake | Contributes to obesity, which increases blood pressure and cholesterol levels |
| Low fruit and vegetable intake | Missing out on protective antioxidants (vitamins C and E, beta-carotene), fibre, and potassium |
| Low fibre intake | Soluble fibre helps to lower blood cholesterol. Insufficient fibre increases CVD risk |
| Excessive alcohol | Raises blood pressure, contributes to weight gain, can damage the heart muscle directly |
| Obesity | Increases blood pressure, blood cholesterol, and the risk of type 2 diabetes — all of which increase CVD risk |
Cholesterol is a fat-like substance found in the blood. It is essential for cell membranes, hormone production, and vitamin D synthesis, but too much of the wrong type is harmful.
| Type | Full Name | Role | Effect on CVD |
|---|---|---|---|
| LDL | Low-density lipoprotein | Carries cholesterol from the liver to the cells | "Bad" — excess LDL deposits cholesterol in artery walls, forming plaques |
| HDL | High-density lipoprotein | Carries cholesterol from the cells back to the liver for disposal | "Good" — removes cholesterol from arteries, reducing plaque formation |
| Factor | Effect |
|---|---|
| Saturated fat | Raises LDL (bad) cholesterol |
| Trans fat | Raises LDL and lowers HDL cholesterol (worst combination) |
| Unsaturated fat (mono- and polyunsaturated) | Helps to lower LDL and raise HDL cholesterol |
| Soluble fibre (oats, beans, lentils, fruit) | Binds to cholesterol in the gut and removes it from the body, lowering blood cholesterol |
| Omega-3 fatty acids (oily fish, walnuts, flaxseeds) | Reduce triglycerides (another type of blood fat) and have anti-inflammatory effects on blood vessels |
| Plant sterols and stanols | Found naturally in small amounts in plants; also added to some spreads and yoghurts. Block cholesterol absorption in the gut |
Exam Tip: Remember the simple rule: saturated fat raises LDL (bad), unsaturated fat lowers LDL (good). Oily fish provides omega-3, which reduces triglycerides and inflammation. Soluble fibre removes cholesterol from the body.
Blood pressure is the force with which blood pushes against the walls of the arteries as the heart pumps it around the body. It is measured in millimetres of mercury (mmHg) and written as two numbers:
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