How does long-term diet contribute to and help prevent cardiovascular disease?
Explain the development of cardiovascular disease and the dietary factors that increase or reduce its risk
Cardiovascular disease develops as fatty plaques narrow arteries. Diets high in saturated fat, salt and energy raise the risk, while fibre, unsaturated fats and plenty of vegetables help lower it.
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What this dot point is asking
You need to explain how cardiovascular disease develops, then explain which dietary factors increase the risk and which reduce it.
How cardiovascular disease develops
Cardiovascular disease (CVD) is a group of conditions affecting the heart and blood vessels, including coronary heart disease and stroke. Its main underlying process is atherosclerosis.
In atherosclerosis, fatty deposits called plaques build up on the inner walls of arteries. The arteries become narrowed and stiffened, so blood flow is reduced and blood pressure rises. If a plaque ruptures, a blood clot can form and block the artery. A blockage in an artery supplying the heart causes a heart attack; a blockage or bleed in the brain causes a stroke.
Cholesterol carried in the blood plays a key role. Low-density lipoprotein (LDL) cholesterol tends to deposit in artery walls, while high-density lipoprotein (HDL) helps remove it, which is why the balance of blood lipids matters.
Dietary factors that increase risk
- Saturated and trans fats
- Diets high in saturated fat (fatty meats, butter, many processed foods) and trans fats tend to raise LDL cholesterol, promoting plaque build-up. Trans fats are particularly harmful.
- Salt (sodium)
- A high salt intake raises blood pressure, which damages artery walls and strains the heart, increasing CVD risk.
- Excess energy
- Diets high in energy from fat and sugar promote overweight and obesity, which are linked to high blood pressure, unhealthy blood lipids and type 2 diabetes, all of which raise CVD risk.
Dietary factors that reduce risk
- Unsaturated fats
- Replacing some saturated fat with unsaturated fats from oils, nuts and oily fish helps improve blood lipids. Oily fish supplies omega-3 fatty acids linked to heart health.
- Dietary fibre
- Soluble fibre from oats, legumes, fruit and vegetables can help lower LDL cholesterol.
- Fruit, vegetables and wholegrains
- These supply fibre, potassium and protective compounds, and support a healthy weight and blood pressure.
- Less salt and moderate energy intake
- Reducing salt helps control blood pressure, and matching energy intake to needs helps maintain a healthy weight.
These align with the Australian Dietary Guidelines, which is why the guidelines emphasise vegetables, wholegrains, lean proteins and limiting saturated fat and salt.
Why this matters
CVD is a leading cause of death, and much of its risk is influenced by modifiable diet and lifestyle factors. This makes it a central example of the diet to disease link and a common examination case study, where you may be asked to evaluate a diet and recommend changes.
In short, cardiovascular disease develops through atherosclerosis driven by blood cholesterol, blood pressure and body weight, and diets low in saturated fat and salt but rich in unsaturated fats, fibre, fish and vegetables help reduce the risk.
Exam-style practice questions
Practice questions written in the style of SACE Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2019 SACE Stage 23 marksA family frequently consumes packaged, dehydrated instant noodles. Explain the link between pre-prepared meals and hypertension, with reference to a specific Australian dietary guideline.Show worked answer →
Three marks: explain the salt/sodium link to hypertension (about 2 marks) and quote a relevant guideline (1 mark).
Pre-prepared meals such as instant noodles are typically very high in sodium (salt), which is added for flavour and preservation. A diet high in sodium causes the body to retain more water, which increases blood volume and therefore raises blood pressure. Sustained high blood pressure is hypertension, a major risk factor for cardiovascular disease (2 marks).
Australian Dietary Guideline 3 advises Australians to limit intake of foods and drinks containing added salt (and saturated fat and added sugars). Choosing pre-prepared meals frequently works against this guideline because of their high salt content (1 mark).
2018 SACE Stage 21 marksState two functions of omega-3 fatty acids in the human body.Show worked answer →
One mark for a correct function (the original question allocates one mark per function).
Omega-3 fatty acids help maintain heart and cardiovascular health by lowering blood triglyceride levels and reducing the risk of abnormal heart rhythms and blood clots.
Other accepted functions include supporting brain development and function, and reducing inflammation in the body. Omega-3 is a polyunsaturated fat that helps replace saturated fat in the diet, lowering cardiovascular disease risk.